Colorectal Cancers Soon After Colonoscopy
Colorectal Cancers Soon After Colonoscopy
Objective. Some individuals are diagnosed with colorectal cancer (CRC) despite recent colonoscopy. We examined individuals under colonoscopic surveillance for colonic adenomas to assess possible reasons for diagnosing cancer after a recent colonoscopy with complete removal of any identified polyps.
Design. Primary data were pooled from eight large (>800 patients) North American studies in which participants with adenoma(s) had a baseline colonoscopy (with intent to remove all visualised lesions) and were followed with subsequent colonoscopy. We used an algorithm based on the time from previous colonoscopy and the presence, size and histology of adenomas detected at prior exam to assign interval cancers as likely being new, missed, incompletely resected (while previously an adenoma) or due to failed biopsy detection.
Results. 9167 participants (mean age 62) were included in the analyses, with a median follow-up of 47.2 months. Invasive cancer was diagnosed in 58 patients (0.6%) during follow-up (1.71 per 1000 person-years follow-up). Most cancers (78%) were early stage (I or II); however, 9 (16%) resulted in death from CRC. We classified 30 cancers (52%) as probable missed lesions, 11 (19%) as possibly related to incomplete resection of an earlier, non-invasive lesion and 14 (24%) as probable new lesions. The cancer diagnosis may have been delayed in three cases (5%) because of failed biopsy detection.
Conclusions. Despite recent colonoscopy with intent to remove all neoplasia, CRC will occasionally be diagnosed. These cancers primarily seem to represent lesions that were missed or incompletely removed at the prior colonoscopy and might be avoided by increased emphasis on identifying and completely removing all neoplastic lesions at colonoscopy.
Colorectal cancer (CRC) is the second most common cause of cancer death in the USA and its prevention and early detection are a significant public health concern. The United States Preventive Services Task Force and the American Cancer Society in collaboration with the US Multi-Society Task Force, among other organisations, recommend that adults be screened for CRC. These recommendations are based on high quality evidence that screening can reduce CRC mortality and incidence and recent studies show that nationally CRC incidence and mortality are declining.
Colonoscopy appears to be a highly effective modality for screening and affords the opportunity to view the entire colorectal mucosa and simultaneously remove premalignant adenomas before they become invasive cancers. While no large randomised controlled trials of screening colonoscopy have been reported, recent observational studies suggest that colonoscopy in the prior 10 years may reduce CRC incidence and mortality by over 60%.
Despite evidence of colonoscopy's effectiveness, some individuals are diagnosed with CRC relatively soon after a colonoscopy that deemed the colon to be free of neoplasia. These 'interval' cancers (ie, those that appear to arise between serial colonoscopies) have been observed in studies examining large administrative data sets and national screening programmes as well as in smaller clinical studies. However, relatively few reports have explored the possible explanations for these interval cancers. Investigators from the Polyp Prevention Trial (PPT) identified 13 CRCs that occurred during the follow-up phase of that study. Using an algorithm, they estimated that roughly a half were potentially avoidable, being likely missed or the result of a prior incompletely resected polyp. At a single Veterans Affairs (VA) centre, records of 45 patients with interval CRCs were examined and 12 (27%) developed cancer in the same segment of the colon from which a prior polyp had been removed. Incomplete resection of a prior lesion was felt to be the explanation in those cases. In a clinical series of cases from 20 Indiana hospitals, 47 CRCs were identified within 3 years of a colonoscopy not detecting cancer. After review, 27 cases (57%) were felt to be missed cancers.
We used a pooled dataset from eight large prospective studies to assess both the frequency of cancer after complete colonoscopy and the possible reasons for the occurrence of these lesions.
Abstract and Introduction
Abstract
Objective. Some individuals are diagnosed with colorectal cancer (CRC) despite recent colonoscopy. We examined individuals under colonoscopic surveillance for colonic adenomas to assess possible reasons for diagnosing cancer after a recent colonoscopy with complete removal of any identified polyps.
Design. Primary data were pooled from eight large (>800 patients) North American studies in which participants with adenoma(s) had a baseline colonoscopy (with intent to remove all visualised lesions) and were followed with subsequent colonoscopy. We used an algorithm based on the time from previous colonoscopy and the presence, size and histology of adenomas detected at prior exam to assign interval cancers as likely being new, missed, incompletely resected (while previously an adenoma) or due to failed biopsy detection.
Results. 9167 participants (mean age 62) were included in the analyses, with a median follow-up of 47.2 months. Invasive cancer was diagnosed in 58 patients (0.6%) during follow-up (1.71 per 1000 person-years follow-up). Most cancers (78%) were early stage (I or II); however, 9 (16%) resulted in death from CRC. We classified 30 cancers (52%) as probable missed lesions, 11 (19%) as possibly related to incomplete resection of an earlier, non-invasive lesion and 14 (24%) as probable new lesions. The cancer diagnosis may have been delayed in three cases (5%) because of failed biopsy detection.
Conclusions. Despite recent colonoscopy with intent to remove all neoplasia, CRC will occasionally be diagnosed. These cancers primarily seem to represent lesions that were missed or incompletely removed at the prior colonoscopy and might be avoided by increased emphasis on identifying and completely removing all neoplastic lesions at colonoscopy.
Introduction
Colorectal cancer (CRC) is the second most common cause of cancer death in the USA and its prevention and early detection are a significant public health concern. The United States Preventive Services Task Force and the American Cancer Society in collaboration with the US Multi-Society Task Force, among other organisations, recommend that adults be screened for CRC. These recommendations are based on high quality evidence that screening can reduce CRC mortality and incidence and recent studies show that nationally CRC incidence and mortality are declining.
Colonoscopy appears to be a highly effective modality for screening and affords the opportunity to view the entire colorectal mucosa and simultaneously remove premalignant adenomas before they become invasive cancers. While no large randomised controlled trials of screening colonoscopy have been reported, recent observational studies suggest that colonoscopy in the prior 10 years may reduce CRC incidence and mortality by over 60%.
Despite evidence of colonoscopy's effectiveness, some individuals are diagnosed with CRC relatively soon after a colonoscopy that deemed the colon to be free of neoplasia. These 'interval' cancers (ie, those that appear to arise between serial colonoscopies) have been observed in studies examining large administrative data sets and national screening programmes as well as in smaller clinical studies. However, relatively few reports have explored the possible explanations for these interval cancers. Investigators from the Polyp Prevention Trial (PPT) identified 13 CRCs that occurred during the follow-up phase of that study. Using an algorithm, they estimated that roughly a half were potentially avoidable, being likely missed or the result of a prior incompletely resected polyp. At a single Veterans Affairs (VA) centre, records of 45 patients with interval CRCs were examined and 12 (27%) developed cancer in the same segment of the colon from which a prior polyp had been removed. Incomplete resection of a prior lesion was felt to be the explanation in those cases. In a clinical series of cases from 20 Indiana hospitals, 47 CRCs were identified within 3 years of a colonoscopy not detecting cancer. After review, 27 cases (57%) were felt to be missed cancers.
We used a pooled dataset from eight large prospective studies to assess both the frequency of cancer after complete colonoscopy and the possible reasons for the occurrence of these lesions.
Source...