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Original Article Prognosis of Korean patients with familial adenomatous polyposis who did not undergo colectomy: a retrospective study
Min Kwan Kwon1orcid, Jin Hee Noh2,#orcid, Ji Yong Ahn2orcid, Woochang Lee3orcid, Seok-Byung Lim4orcid, Yong Sang Hong5orcid, Seung Wook Hong2,6orcid, Sung Wook Hwang2,7orcid, Sang Hyoung Park2,7orcid, Byong Duk Ye2,7orcid, Jeong-Sik Byeon2orcid, Seung-Jae Myung2,6orcid, Suk-Kyun Yang2,7orcid, Dong-Hoon Yang2,6orcid

DOI: https://doi.org/10.5946/ce.2025.191
Published online: December 31, 2025

1Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

2Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

3Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

4Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

5Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

6Digestive Diseases Research Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

7Inflammatory Bowel Disease Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

Correspondence: Dong-Hoon Yang Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea E-mail: dhyang@amc.seoul.kr
#Current affiliation: Department of Internal Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea
• Received: June 18, 2025   • Revised: August 22, 2025   • Accepted: August 23, 2025

© 2025 Korean Society of Gastrointestinal Endoscopy

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  • Background/Aims
    The International Society for Gastrointestinal Hereditary Tumors polyposis scoring system (IPSS) categorizes familial adenomatous polyposis (FAP) according to the burden of colorectal polyps and histology. However, the prognosis of patients with uncolectomized FAP has not been established.
  • Methods
    Medical records of patients diagnosed with FAP between 1991 and 2021 were reviewed, and the IPSS stage was determined. The cumulative upstaging rate and risk factors for IPSS upstaging during surveillance were analyzed in patients without colectomies.
  • Results
    Among 237 patients, 35 (28.9%) with IPSS stages 0–2 did not undergo colectomy. The cumulative risk of upstaging was 0%, 31%, 54%, and 73% at 1, 3, 7, and 10 years after FAP diagnosis, respectively. In univariate analysis, age (hazard ratio [HR], 1.05; 95% confidence interval [CI], 1.01–1.08; p=0.014) and having an ampulla of Vater adenoma (HR, 3.95; 95% CI, 1.17–13.30; p=0.027) were associated with upstaging. Multivariate analysis revealed that each 1-year increase in age was an independent risk factor of upstaging (adjusted HR, 1.04; 95% CI, 1.01–1.09; p=0.027).
  • Conclusions
    In our analysis, patients with uncolectomized FAP and IPSS stages 0–2 at diagnosis showed a time-dependent progression in the IPSS stage.
  • Keywords: Adenoma; Adenomatous polyposis coli; Ampulla of vater; Colorectum; Surveillance
Colorectal cancer (CRC) is the third most common malignancy worldwide, and approximately 12% to 35% of CRCs are due to genetic factors.1 It is estimated that 10% to 25% of CRCs are familial CRC, highlighting a genetic tendency when considering family history, while hereditary CRC, which is caused by germline mutations, accounts for approximately 2% to 5% of all CRCs.2 Hereditary CRC is largely divided into Lynch syndrome and hereditary polyposis syndrome, and the most common hereditary polyposis syndrome is familial adenomatous polyposis (FAP).3,4 FAP is inherited from dominant genes, and the lifetime probability of developing CRC without treatment is nearly 100%.5-7 The standard treatment for FAP is total proctocolectomy, and patients typically undergo surgery during their mid- or late-teens to early twenties.6,8 The need for surgery is determined based on the presence of (1) multiple colon polyps that are larger than 1 cm, (2) a polyp that is histologically close to malignancy, and (3) a large number of polyps or polyps with a large size, which disables endoscopic resection.9,10
Previously, there was no standard classification system for evaluating the severity of colorectal manifestations of FAP. However, in 2016, the International Society for Gastrointestinal Hereditary Tumors (InSiGHT) proposed the InSiGHT polyposis scoring system (IPSS) for patients with FAP based on the number, size, and degree of dysplasia of colon polyps.11 The IPSS classifies patients diagnosed with FAP based on the severity of their condition. In addition, patients with a low IPSS stage may receive surveillance without colectomy until upstaging or progression to CRC occurs. Therefore, the IPSS may help determine the optimal timing for surgery in patients with FAP with a relatively low burden of colorectal polyps.
Recently, a Japanese multicenter cohort study reported the long-term follow-up data of patients with non-dense (≤1,000 polyps) FAP.12 Among 250 patients with FAP, 142 underwent prophylactic colectomy, and 108 were followed without colectomy. During a median follow-up of 13 years, CRC occurred in 24 of the 108 patients who did not undergo prophylactic colectomy. However, 21 of the 24 CRC cases were diagnosed at the Tis stage, and no mortality was reported. Another Japanese multicenter study performed intensive polypectomy for polyps ≥10 mm, instead of prophylactic colectomy, for 166 patients with FAP who had <100 colorectal polyps; only 9.6% of them required colectomy during the 5-year follow-up.13 These two Japanese studies suggest that colonoscopic surveillance without prophylactic colectomy is feasible for well-selected patients with FAP and a low burden of colorectal polyps.
In Korea, a very short-term, pharmacological interventional study reported no significant effect of metformin for reducing the burden of colorectal and duodenal polyps in patients with FAP.14 Another retrospective single-center study of patients with FAP who underwent restorative proctocolectomy showed that the cumulative incidence of pouch adenoma was 15.2%, 29.6%, and 44.1% at 5, 10, and 15 years after surgery, respectively.15 In addition, a recent single-center cohort study reported that the incidence of advanced neoplasms in those with non-hereditary colorectal polyposis (defined as having ≥10 polyps without known genetic mutations) was 20.9% during a median surveillance period of 4.1 years.16 However, little is known about the clinical course of FAP patients who did not undergo colectomy in the Korean population. This study aimed to investigate the prognosis of Korean patients with FAP who did not undergo colectomy by assessing the progression of colorectal polyposis using the IPSS during surveillance.
Diagnostic criteria for FAP
FAP was diagnosed based on either clinical or genetic criteria.17,18 Clinically, patients with ≥100 adenomatous colorectal polyps and those with <100 adenomatous polyps but with a family history of FAP were diagnosed with FAP. Genetically, those with ≥10 adenomatous polyps and germline mutations in the adenomatous polyposis coli (APC) gene were diagnosed with FAP. Diagnostic studies, including colonoscopy and esophagogastroduodenoscopy, were performed, and colectomy was recommended for patients who reached the optimal time of surgery.
Study design and data collection
This was a single-institution retrospective cohort study. Data of patients diagnosed with FAP between January 1991 and December 2021 were retrieved from our institutional database. Data regarding demographics, family history, endoscopic and pathological findings, surgical history, and APC mutation status were collected for analysis. The presence of ampulla of Vater (AoV), non-ampullary duodenal, and gastric adenomas was confirmed by endoscopic findings and pathological reports of biopsy specimens. Among the patients with FAP who were recommended to undergo prophylactic total proctocolectomy, those who did not undergo colectomy within 6 months after the recommendation were considered patients with FAP who delayed or refused prophylactic colectomy. Based on medical records, the reasons for not undergoing colectomy were investigated.
This study focused primarily on the clinical course and IPSS progression in Korean patients with FAP who did not undergo prophylactic colectomy. Although data on patients who underwent colectomy are presented for background context, detailed comparative analyses between the colectomized and uncolectomized groups were beyond the scope of this manuscript.
Surveillance strategy
Surveillance colonoscopy was routinely performed at 6–12 -month intervals, depending on the clinician’s assessment of the polyp burden and risk factors. Polypectomy was generally indicated for polyps >1 cm or for those exhibiting suspicious features on endoscopy. High-grade dysplasia (HGD) detected during surveillance was initially managed with intensive endoscopic resection and close follow-up of selected patients who refused or delayed surgery. In cases where surgery was declined or contraindicated, repeated endoscopic interventions were performed to control the polyp progression.
InSiGHT polyposis scoring system
The IPSS stage was classified as follows (Table 1)11: stage 0, <20 polyps, all <5 mm in size; stage 1, 20–200 polyps that were mostly <5 mm and no polyps >1 cm; stage 2, 200–500 polyps and <10 polyps >1 cm; stage 3, 500–1,000 polyps or any number of polyps if 10–50 were >1 cm and amenable to complete polypectomy; and stage 4, >1,000 polyps, any polyps grown to confluence and not amenable to simple polypectomy, or any invasive CRC. However, upstaging to stage 4 was warranted if HGD was identified in patients with stages 0–3 disease.11 Among those with IPSS stages 0–3, patients who were followed up for at least 6 months were evaluated for upstaging events.
APC mutation analysis
Mutations in APC on chromosomes 5q21–q22 were analyzed by Sanger sequencing or next-generation sequencing at the Asan Medical Center. Detailed methods for APC mutation analysis are provided in Supplementary Table 1.19,20
Outcomes and statistical analysis
The primary outcome was defined as a change in the status of adenomatous colorectal polyposis, graded using the IPSS and specifically focusing on the cumulative rate of IPSS upstaging during surveillance. Secondary outcomes included identification of risk factors associated with IPSS upstaging and progression to CRC. Categorical variables were compared using the χ2 or Fisher’s exact test, and continuous variables were compared using the Student t-test or Mann-Whitney U-test. The Kaplan-Meier method was used to analyze the cumulative IPSS upstaging rate in patients with uncolectomized FAP. The log-rank test was conducted by dividing the groups with and without risk factors, and the cumulative rate of upstaging was confirmed in both groups. The risk factors for IPSS upstaging over time in patients with uncolectomized FAP were analyzed using Cox proportional hazards regression. All significance tests were two-tailed, and p-values <0.05 were considered statistically significant. Statistical analysis was performed using the IBM SPSS for Windows software ver. 24.0 (IBM Corp.), and the Kaplan-Meier curve, log-rank test, and Cox proportional hazards regression were performed using R Studio ver. 4.1.1 (R Foundation for Statistical Computing).
Ethics statement
This retrospective observational study was approved by the Institutional Review Board (IRB) of Asan Medical Center (IRB no. 2022-1297). Information identified in the electronic database was encrypted to protect patient privacy. As no intervention was involved and no patient-identifying information was included, the IRB waived the requirement for informed consent.
Baseline characteristics and clinical features of patients with FAP
Of the 237 patients with FAP, 186 (78.5%) underwent colectomy at diagnosis or during follow-up, while 51 (21.5%) did not and were managed with surveillance alone (Fig. 1). Detailed characteristics of both groups are summarized in Table 2. The reasons for not undergoing a prophylactic colectomy are listed in Table 3.
Analysis of uncolectomized and colectomized groups by IPSS stage in patients with FAP
Table 4 shows the IPSS stages of the patients with FAP in the uncolectomized and colectomized groups. Only two patients had stage 0 disease; therefore, stages 0–1 were assessed as a single group. Of the 51 patients who did not undergo colectomy, seven who initially had IPSS stage 4 disease with no possibility of upstaging were excluded, and 44 patients with IPSS stages 0–2 disease had a possibility of upstaging. The distribution of IPSS stages differed significantly between the uncolectomized and colectomized groups (p<0.001), indicating a significant difference in the severity of polyposis by colectomy status.
Cumulative IPSS upstaging rate in patients with uncolectomized FAP
Among the 44 patients with uncolectomized IPSS stages 0–2 FAP, 35 were followed up for at least six months. The number of colonoscopies performed during the follow-up was (mean±standard deviation) 4.1±3.7. The cumulative upstaging rates in this group were 0%, 31%, 54%, and 73% at 1, 3–5, 7, and 10 years after diagnosis, respectively (Fig. 2). In addition, among the patients whose stage increased, two patients were raised to stage 4 in this study because of HGD detected in the colonic polyps. One patient progressed from stage 2 to 4 within 29.4 months from the time of diagnosis. The other patient progressed from stage 1 to 4 within 33.6 months from the time of diagnosis. HGD was confirmed; therefore, these two patients did not undergo colectomy and underwent regular surveillance with colonoscopy and polypectomy.
Univariate analysis for the risk factors of upstaging in patients with uncolectomized IPSS stages 0–2 FAP
According to the log-rank tests for potential risk factors for the cumulative upstaging rate in patients with uncolectomized stages 0–2 disease, only the presence of AoV adenomas showed statistically significant differences (p=0.017, Fig. 3). The cumulative upstaging rates were 0% at 1 year and 73% at 3–6 years after diagnosis in the group with stages 0–2 AoV adenoma and were 0% at 1 year, 24% at 3–5 years, and 37% at 6 years in the group without AoV adenomas.
Cox proportional hazard regression for upstaging in patients with uncolectomized IPSS stages 0–2 FAP
Table 5 shows the hazard ratio (HR) for upstaging in patients with uncolectomized IPSS stages 0–2 FAP according to univariate and multivariate analyses using Cox proportional hazard regression. In the univariate analysis, each 1-year increase in age (HR, 1.05; 95% confidence interval [CI], 1.01–1.08; p=0.014) and the presence of AoV adenomas (HR, 3.95; 95% CI, 1.17–13.30; p=0.027) were significantly associated with IPSS upstaging during the follow-up. In addition to the presence of AoV adenomas, the HRs were examined to determine whether the presence of non-ampullary duodenal adenomas and duodenal adenomas affected the upstaging status; however, these were not statistically significant factors. In the multivariate analysis, each 1-year increase in age was the only significant factor associated with an upstaging event during the follow-up of patients with uncolectomized stages 0–2 FAP (adjusted HR, 1.04; 95% CI, 1.01–1.09; p=0.027). To further assess the effect of age on upstaging, patients were dichotomized into two subgroups based on an age of 30 years (<30 vs.≥30 years), reflecting the typical timing of colectomy in clinical practice.8 Univariate analyses of both subgroups showed that each 1-year increase in age was not a statistically significant predictor of upstaging (<30 years group: HR, 1.09; 95% CI, 0.98–1.20; p=0.12 and ≥30 years group: HR, 1.01; 95% CI, 0.95–1.08; p=0.70). Other risk factors were not significant within these subgroups, and therefore, multivariate analyses were not performed. In terms of the age distribution, two patients were younger than their teens, 11 were in their teens, 11 were in their twenties, seven were in their thirties, and four were >40 years old.
FAP is a hereditary polyposis syndrome that occurs in the large intestine and has precancerous features resulting in progression to CRC in almost all affected individuals.5-7 The current treatment consensus is to perform total proctocolectomy in the mid-to-late teens and early-to-mid-twenties.5 However, many young patients with FAP may be concerned about undergoing surgery at a young age. Factors such as a fear of surgery, potential complications, anxiety, and the discomfort of living without one’s own colon can contribute to the desire to delay total proctocolectomy for as long as possible. In our database, proctocolectomy was postponed based on medical advice due to young (<18 years) age (n=11), attenuated FAP (n=7), and extreme (body mass index >35 kg/m2) obesity (n=1). However, 41.2% of patients wanted to delay or refuse colectomy contrary to the doctor’s recommendation.
In this study, we classified Korean patients with FAP according to the IPSS stage, and the progression of polyposis in patients without colectomies was measured based on an upstaging event during the follow-up. We found that patients with uncolectomized IPSS stages 0–2 FAP showed a time-dependent increase in the cumulative upstaging rate. However, no one required a colectomy due to an increased polyp burden or histologic progression during the follow-up. No CRC developed during a median follow-up period of 34 months, and histologic progression to HGD occurred in only two patients, at 29.4 and 33.6 months after FAP diagnosis. Importantly, both patients were successfully managed with endoscopic treatment alone, without undergoing colectomy. These cases suggest that in selected patients, intensive endoscopic management may be a feasible alternative to surgery, even after upstaging to IPSS stage 4 due to HGD. Prior to our study, studies from Japan suggested that active surveillance of patients with uncolectomized FAP with a low polyp burden is feasible. In a retrospective Japanese study, colonoscopic surveillance of patients with uncolectomized FAP and non-dense polyps was performed at three Japanese centers for a median of 5.1 years. During this period, 2 of the 90 patients underwent colectomy due to the progression of the polyp burden from non-dense to dense polyposis. However, CRC occurred in none of the 90 patients with FAP.21 A more recent Japanese multicenter study performed intensive polypectomy for polyps ≥10 mm in patients with uncolectomized FAP and <100 colorectal polyps (n=166).13 With 6.6 times of colonoscopic intervention performed in 5 years, two patients were diagnosed with T1 CRC, and 35 (21.1%) patients were diagnosed with HGD or intramucosal cancer. However, 90.4% of the patients completed the 5-year follow-up without colectomy. These two Japanese studies, with approximately 5 years of follow-up data, suggest that intensive colonoscopic surveillance without prophylactic colectomy may be applied to well-selected patients with FAP and a low burden of colorectal polyps. According to long-term follow-up data from the nationwide Japanese FAP registration,12 CRC occurred in 24 of 108 patients without colectomies during a median follow-up of 13 years. However, 21 of 24 CRC cases were diagnosed at the Tis stage, and no mortality was reported in this group.12 These findings, including ours, suggest that intensive surveillance for patients with uncolectomized FAP and a low burden of colorectal polyps may be warranted for a minimum of approximately 3 to 5 years after diagnosis. The optimal surveillance interval for patients with FAP with a lower IPSS stage (stages 0–3) is not easily determined. However, the latest post-polypectomy surveillance guidelines recommend a 1-year interval for patients with >10 adenomas during the index colonoscopy.22,23 A surveillance interval of ≤1 year may be appropriate for patients with uncolectomized FAP and a low polyp burden.
We also analyzed the risk factors for upstaging events (i.e., progression of colorectal polyps) in patients with uncolectomized IPSS stages 0–2 FAP. Multivariate analysis showed that each 1-year increase in age was the only independent risk factor for upstaging during the follow-up. Whether chronological age or the aging process is a true risk factor for upstaging events in patients with FAP is unknown. However, given that the progression from adenoma to CRC requires multiple steps at the molecular level, aging-related processes or the duration of FAP may be risk factors for the progression of FAP. This study focused on patients initially diagnosed at IPSS stages 0–2, and our findings suggest that the disease duration since diagnosis may be more relevant to the IPSS upstaging risk than the chronological age per se. Notably, this interpretation applies specifically to patients with early-stage disease, as those diagnosed at older ages may represent delayed detection rather than an intrinsically slower disease progression. Therefore, the age at diagnosis must be carefully interpreted, especially in the context of a delayed diagnosis, when assessing the prognosis of patients with FAP. In addition to age, the univariate analysis suggested an association between the presence of AoV adenomas and the cumulative upstaging rate in this group, although multivariate analysis failed to reveal statistical significance. According to a previous study, AoV adenomas occurred more frequently in patients with FAP and a high colorectal polyp burden than in those with a low polyp burden.12 Therefore, the association between AoV adenomas and the progression of colorectal polyps during surveillance in patients with uncolectomized FAP should be investigated in additional studies.
This study had some limitations. First, this study was not free of selection bias. This retrospective study was conducted at a single institution. Collecting and analyzing large-scale patient data from multiple centers could produce more accurate results. The second limitation was that no baseline study previously proposed the timing of upstaging according to IPSS in patients with FAP who were monitored without polypectomy. In this study, patients with FAP in Korea who were enrolled underwent regular polypectomy through colonoscopy during surveillance without undergoing surgery. Third, the median follow-up period for patients with uncolectomized IPSS stages 0–2 FAP was 34 months. In studies that confirmed upstaging, a small median follow-up period could be a disadvantage. Hence, additional studies with longer follow-up periods in patients with uncolectomized FAP are needed. Finally, not all patients with FAP underwent APC mutation testing. Therefore, some of the patients clinically diagnosed with FAP in our cohort may have other adenomatous polyposis, such as MUTYH-associated polyposis. Additionally, our study did not systematically collect data on extracolonic malignancies, such as hepatobiliary and pancreatic cancers, although thyroid cancer and desmoid tumors were reported. This restricted our understanding of the prevalence and potential association between extracolonic malignancies and the colectomy status in patients with FAP. Future large-scale and comprehensive studies are warranted to evaluate these extracolonic tumor risks and their relationship with prophylactic surgery for FAP. Despite these limitations, this study was significant as it demonstrated the feasibility of assessing the severity of FAP in Korean patients using the IPSS and provided practical insights and relevance for clinicians involved in the management and follow-up of patients with FAP in Korea.
In conclusion, we classified Korean patients with FAP according to the IPSS stage, and the cumulative IPSS upstaging rates were 0%, 31%, 54%, and 73% at 1, 3, 7, and 10 years after diagnosis, respectively, in the IPSS stage 0–2 FAP patients who did not undergo colectomy. Therefore, Korean patients with IPSS stages 0–2 FAP who refuse prophylactic total proctocolectomy can be followed up with meticulous surveillance colonoscopy. Large-scale, long-term follow-up studies are necessary to ascertain the duration of prophylactic colectomy in patients with early IPSS-stage FAP.
Supplementary Table 1. APC gene mutation analysis at Asan Medical Center.
ce-2025-191-Supplementary-Table-1.pdf
Supplementary materials related to this article can be found online at https://doi.org/10.5946/ce.2025.191.
Fig. 1.
Flowchart for the enrollment and selection of patients. FAP, familial adenomatous polyposis; IPSS, International Society for Gastrointestinal Hereditary Tumors polyposis scoring system.
ce-2025-191f1.jpg
Fig. 2.
Cumulative upstaging rate in the International Society for Gastrointestinal Hereditary Tumors polyposis scoring system stage 0–2 familial adenomatous polyposis patients who did not undergo colectomy.
ce-2025-191f2.jpg
Fig. 3.
Comparison of cumulative upstaging rate according to the presence of ampulla of Vater adenoma in International Society for Gastrointestinal Hereditary Tumors polyposis scoring system stage 0–2, non-colectomized familial adenomatous polyposis patients. AoV, ampulla of Vater.
ce-2025-191f3.jpg
ce-2025-191f4.jpg
Table 1.
International Society for Gastrointestinal Hereditary Tumors polyposis scoring system
Stage Polyp description
0 <20 Polyps, all <5 mm
1a) 20–200 Polyps, most <5 mm, none >1 cm
2a) 200–500 Polyps, <10 that are >1 cm
3a) 500–1,000 Polyps or any number if there are 10–50 that are >1 cm and amenable to complete polypectomy
4 >1,000 Polyps and/or any polyps grown to confluence and not amenable to simple polypectomy; any invasive cancer

a)Presence of high-grade dysplasia warrants upstaging of patient to stage 4.

Table 2.
Baseline characteristics and clinical features of familial adenomatous polyposis patients
Characteristic Total (n=237) Uncolectomized (n=51) Colectomized (n=186) p-value
Age at diagnosis (yr) 29.0 (23.0–36.0) 26.0 (19.0–34.0) 30.0 (23.0–38.0) 0.64
Male sex 134 (56.5) 28 (54.9) 106 (57.0) 0.79
Body mass index (kg/m2) 22.7 (20.0–24.7) 22.7 (19.8–24.6) 22.7 (20.4–24.7) 0.20
Underlying disease
 Diabetes 2 (0.8) 0 (0) 2 (1.0) 0.46
 Hypertension 8 (3.4) 1 (2.0) 7 (3.8) 0.53
 Colorectal cancer 73 (30.8) 7 (13.7) 66 (35.5) 0.004**
 Duodenal adenoma
  Overall 116 (48.9) 20 (39.2) 96 (51.6) 0.20
  AoV adenoma 27 (11.4) 6 (11.8) 21 (11.3) 0.13
  Non-ampullary adenoma 108 (45.6) 17 (33.3) 91 (48.9) 0.028*
 Gastric adenoma 36 (15.2) 4 (7.8) 32 (17.2) 0.073
 Thyroid cancer 11 (4.6) 2 (3.9) 9 (4.8) 0.89
 Desmoid tumor 11 (4.6) 4 (7.9) 7 (3.8) 0.28
Familial history
 FAP 68 (28.7) 16 (31.4) 52 (28.0) 0.85
 Colorectal cancer 65 (27.4) 6 (11.8) 59 (31.7) 0.005**
Identified APC gene mutation 112 (47.3) 36 (70.6) 76 (40.9) <0.001***
Follow-up, months 77.0 (32.5–134.0) 21.0 (6.0–65.0) 93.5 (46.0–145.0) <0.001***

Values are presented as median (interquartile range) or number (%).

AoV, ampulla of Vater; FAP, familial adenomatous polyposis; APC, adenomatous polyposis coli.

*p<0.05,

**p<0.01,

***p<0.001.

Table 3.
Reasons for not undergoing prophylactic total proctocolectomy in the Korean FAP patients
Reasons Total (n=51)
Patient’s reluctance or refusal to undergo surgery 21 (41.2)
Young age (<18 yr) 11 (21.6)
Surveillance due to low burden of polyps (attenuated FAP) 7 (13.7)
Chemotherapy due to unresectable CRC/desmoid tumor 5 (9.8)
Extreme (BMI>35 kg/m2) obesity 1 (2.0)
Unknown causes 6 (11.8)

Values are presented as number (%).

FAP familial adenomatous polyposis; CRC colorectal cancer; BMI, body mass index.

Table 4.
IPSS stage and follow-up period of uncolectomized and colectomized groups
Total (n=237) Uncolectomized (n=51) Colectomized (n=186) p-value
IPSS stage
 Stage 0–1 71 (30.0) 39 (76.5) 32 (17.2)
 Stage 2 50 (21.1) 5 (9.8) 45 (24.2)
 Stage 3 29 (12.2) 0 (0) 29 (15.6)
 Stage 4 87 (36.7) 7 (13.7) 80 (43.0)
 Total 237 (100.0) 51 (100.0) 186 (100) <0.001***,a)
Follow-up period (mo)
 Stage 0–1 53.0 (16.0–112.0) 31 (14.0–76.0) 98 (41.0–138.0) 0.054*
 Stage 2 99.0 (43.0–178.5) 10 (1.0–18.5) 110 (66.0–181.0) 0.002**
 Stage 3 109.0 (47.5–194.5) 0 (0) 109.0 (47.5–194.5)
 Stage 4 71.0 (35.0–137.0) 5 (0–23.0) 79.0 (41.0–138.8) 0.03*
 Stage 0–2 followed up for at least 6 mo 83.0 (35.0–134.0) 34.0 (16.0–83.0) 104.5 (59.5–160.3) 0.018*

Values are presented as number (%) or median (interquartile range).

IPSS, International Society for Gastrointestinal Hereditary Tumors polyposis scoring system.

a)The p-value reflects the chi-square test for the overall 4×2 table comparing IPSS stages between uncolectomized and colectomized patients.

*p<0.05,

**p<0.01,

***p<0.001.

Table 5.
Univariate and multivariate analyses of risk factors for upstaging in IPSS stage 0–2 patients who did not undergo surgery
Risk factor Univariate analysis Multivariate analysis
HR (95% CI) p-value aHR (95% CI) p-value
Age (per year increase) 1.05 (1.01–1.08) 0.014* 1.04 (1.01–1.09) 0.027*
 Age <30 yr (subgroup) 1.09 (0.98–1.20) 0.12
 Age ≥30 yr (subgroup) 1.01 (0.95–1.08) 0.70
Male sex 0.87 (0.33–2.29) 0.80
Body mass index (kg/m2) 1.02 (0.92–1.14) 0.70
Duodenal adenoma
 Overall 1.44 (0.54–3.79) 0.46
 AoV adenoma 3.95 (1.17–13.30) 0.027* 3.12 (0.93–10.50) 0.065
 Non-ampullary adenoma 1.02 (0.39–2.66) 0.96
Gastric adenoma 0.52 (0.14–1.92) 0.32
Familial history of FAP 0.53 (0.80–1.54) 0.20
Familial history of CRC 1.30 (0.35–4.88) 0.70
APC gene mutation 1.80 (0.51–6.37) 0.40

IPSS, International Society for Gastrointestinal Hereditary Tumors polyposis scoring system; HR, hazard ratio; CI, confidence interval; aHR, adjusted HR; AoV, ampulla of Vater; FAP, familial adenomatous polyposis; CRC, colorectal cancer; APC, adenomatous polyposis coli.

*p<0.05.

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      Prognosis of Korean patients with familial adenomatous polyposis who did not undergo colectomy: a retrospective study
      Image Image Image Image
      Fig. 1. Flowchart for the enrollment and selection of patients. FAP, familial adenomatous polyposis; IPSS, International Society for Gastrointestinal Hereditary Tumors polyposis scoring system.
      Fig. 2. Cumulative upstaging rate in the International Society for Gastrointestinal Hereditary Tumors polyposis scoring system stage 0–2 familial adenomatous polyposis patients who did not undergo colectomy.
      Fig. 3. Comparison of cumulative upstaging rate according to the presence of ampulla of Vater adenoma in International Society for Gastrointestinal Hereditary Tumors polyposis scoring system stage 0–2, non-colectomized familial adenomatous polyposis patients. AoV, ampulla of Vater.
      Graphical abstract

      Fig. 1.

      Fig. 2.

      Fig. 3.

      Graphical abstract

      Prognosis of Korean patients with familial adenomatous polyposis who did not undergo colectomy: a retrospective study
      Stage Polyp description
      0 <20 Polyps, all <5 mm
      1a) 20–200 Polyps, most <5 mm, none >1 cm
      2a) 200–500 Polyps, <10 that are >1 cm
      3a) 500–1,000 Polyps or any number if there are 10–50 that are >1 cm and amenable to complete polypectomy
      4 >1,000 Polyps and/or any polyps grown to confluence and not amenable to simple polypectomy; any invasive cancer
      Characteristic Total (n=237) Uncolectomized (n=51) Colectomized (n=186) p-value
      Age at diagnosis (yr) 29.0 (23.0–36.0) 26.0 (19.0–34.0) 30.0 (23.0–38.0) 0.64
      Male sex 134 (56.5) 28 (54.9) 106 (57.0) 0.79
      Body mass index (kg/m2) 22.7 (20.0–24.7) 22.7 (19.8–24.6) 22.7 (20.4–24.7) 0.20
      Underlying disease
       Diabetes 2 (0.8) 0 (0) 2 (1.0) 0.46
       Hypertension 8 (3.4) 1 (2.0) 7 (3.8) 0.53
       Colorectal cancer 73 (30.8) 7 (13.7) 66 (35.5) 0.004**
       Duodenal adenoma
        Overall 116 (48.9) 20 (39.2) 96 (51.6) 0.20
        AoV adenoma 27 (11.4) 6 (11.8) 21 (11.3) 0.13
        Non-ampullary adenoma 108 (45.6) 17 (33.3) 91 (48.9) 0.028*
       Gastric adenoma 36 (15.2) 4 (7.8) 32 (17.2) 0.073
       Thyroid cancer 11 (4.6) 2 (3.9) 9 (4.8) 0.89
       Desmoid tumor 11 (4.6) 4 (7.9) 7 (3.8) 0.28
      Familial history
       FAP 68 (28.7) 16 (31.4) 52 (28.0) 0.85
       Colorectal cancer 65 (27.4) 6 (11.8) 59 (31.7) 0.005**
      Identified APC gene mutation 112 (47.3) 36 (70.6) 76 (40.9) <0.001***
      Follow-up, months 77.0 (32.5–134.0) 21.0 (6.0–65.0) 93.5 (46.0–145.0) <0.001***
      Reasons Total (n=51)
      Patient’s reluctance or refusal to undergo surgery 21 (41.2)
      Young age (<18 yr) 11 (21.6)
      Surveillance due to low burden of polyps (attenuated FAP) 7 (13.7)
      Chemotherapy due to unresectable CRC/desmoid tumor 5 (9.8)
      Extreme (BMI>35 kg/m2) obesity 1 (2.0)
      Unknown causes 6 (11.8)
      Total (n=237) Uncolectomized (n=51) Colectomized (n=186) p-value
      IPSS stage
       Stage 0–1 71 (30.0) 39 (76.5) 32 (17.2)
       Stage 2 50 (21.1) 5 (9.8) 45 (24.2)
       Stage 3 29 (12.2) 0 (0) 29 (15.6)
       Stage 4 87 (36.7) 7 (13.7) 80 (43.0)
       Total 237 (100.0) 51 (100.0) 186 (100) <0.001***,a)
      Follow-up period (mo)
       Stage 0–1 53.0 (16.0–112.0) 31 (14.0–76.0) 98 (41.0–138.0) 0.054*
       Stage 2 99.0 (43.0–178.5) 10 (1.0–18.5) 110 (66.0–181.0) 0.002**
       Stage 3 109.0 (47.5–194.5) 0 (0) 109.0 (47.5–194.5)
       Stage 4 71.0 (35.0–137.0) 5 (0–23.0) 79.0 (41.0–138.8) 0.03*
       Stage 0–2 followed up for at least 6 mo 83.0 (35.0–134.0) 34.0 (16.0–83.0) 104.5 (59.5–160.3) 0.018*
      Risk factor Univariate analysis Multivariate analysis
      HR (95% CI) p-value aHR (95% CI) p-value
      Age (per year increase) 1.05 (1.01–1.08) 0.014* 1.04 (1.01–1.09) 0.027*
       Age <30 yr (subgroup) 1.09 (0.98–1.20) 0.12
       Age ≥30 yr (subgroup) 1.01 (0.95–1.08) 0.70
      Male sex 0.87 (0.33–2.29) 0.80
      Body mass index (kg/m2) 1.02 (0.92–1.14) 0.70
      Duodenal adenoma
       Overall 1.44 (0.54–3.79) 0.46
       AoV adenoma 3.95 (1.17–13.30) 0.027* 3.12 (0.93–10.50) 0.065
       Non-ampullary adenoma 1.02 (0.39–2.66) 0.96
      Gastric adenoma 0.52 (0.14–1.92) 0.32
      Familial history of FAP 0.53 (0.80–1.54) 0.20
      Familial history of CRC 1.30 (0.35–4.88) 0.70
      APC gene mutation 1.80 (0.51–6.37) 0.40
      Table 1. International Society for Gastrointestinal Hereditary Tumors polyposis scoring system

      Presence of high-grade dysplasia warrants upstaging of patient to stage 4.

      Table 2. Baseline characteristics and clinical features of familial adenomatous polyposis patients

      Values are presented as median (interquartile range) or number (%).

      AoV, ampulla of Vater; FAP, familial adenomatous polyposis; APC, adenomatous polyposis coli.

      p<0.05,

      p<0.01,

      p<0.001.

      Table 3. Reasons for not undergoing prophylactic total proctocolectomy in the Korean FAP patients

      Values are presented as number (%).

      FAP familial adenomatous polyposis; CRC colorectal cancer; BMI, body mass index.

      Table 4. IPSS stage and follow-up period of uncolectomized and colectomized groups

      Values are presented as number (%) or median (interquartile range).

      IPSS, International Society for Gastrointestinal Hereditary Tumors polyposis scoring system.

      The p-value reflects the chi-square test for the overall 4×2 table comparing IPSS stages between uncolectomized and colectomized patients.

      p<0.05,

      p<0.01,

      p<0.001.

      Table 5. Univariate and multivariate analyses of risk factors for upstaging in IPSS stage 0–2 patients who did not undergo surgery

      IPSS, International Society for Gastrointestinal Hereditary Tumors polyposis scoring system; HR, hazard ratio; CI, confidence interval; aHR, adjusted HR; AoV, ampulla of Vater; FAP, familial adenomatous polyposis; CRC, colorectal cancer; APC, adenomatous polyposis coli.

      p<0.05.

      Table 1.

      Table 2.

      Table 3.

      Table 4.

      Table 5.

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