Surveillance Colonoscopy in Low-risk Postpolypectomy Patients
Surveillance Colonoscopy in Low-risk Postpolypectomy Patients
As a consequence of the ever-increasing demand for colonoscopy, endoscopy units are under considerable pressure to meet the UK government's 18-week target time between patient referral and treatment. A 25% increase in demand was seen over 7 years prior to 2005. Introduction of the National Health Service BCSP in April 2006 has resulted in a further increase in the volume of colonoscopy. Therefore, ensuring that surveillance colonoscopy is restricted to those who are most likely to benefit has assumed greater importance. It is interesting to note that while the BCSP has adopted the BSG guideline there has been a small modification in that it does not include an option for a 5-year follow-up colonoscopy in the low-risk group. Our study shows that a minority of 'low-risk' patients (20.4%) actually have a per protocol surveillance colonoscopy. In those that do, we have found that the majority (72.5%) have no further adenomas detected at their surveillance endoscopy and that the yield for detecting advanced neoplasia at the 5-year surveillance colonoscopy is low (7.6%). No cancers were found at surveillance.
A previous UK study found that patients from whom only small (<1 cm) tubular adenomas were removed had no increased risk of developing colon cancer long term and the risk of rectal cancer was profoundly decreased compared with the unexamined population. These results were replicated by a similar study from the USA where no increased incidence of cancer was observed in 751 patients after removal of small (1 cm or less) colorectal polyps. The results from our study confirm that the benefits compared with the risks of surveillance colonoscopy are likely to be small in patients with only one to two small adenomas, and that follow-up colonoscopy, if undertaken at all, should be delayed by at least 5 years. The advanced neoplasia rate, including CRC, in our entire cohort was 6.6%, and we conclude that it is sensible to offer additional colonoscopies in the interim if the patient has new colorectal symptoms.
Some factors point towards higher risk of further adenomas and further advanced neoplasia. We found that male patients were significantly more likely to have further adenomas on subsequent endoscopies compared with female patients. However, it should be noted that a study by Erichsen et al found that in comparison with CRCs, interval cases were more likely to be women (54% vs 48%). We also found that patients with two small adenomas at index were significantly more likely to have advanced neoplasia at subsequent endoscopies compared with patients with only one small adenoma. Furthermore, we found that patients with advanced adenoma(s) at index (i.e. adenomas that had tubulovillous or villous histology or high-grade dysplasia) were significantly more likely to have advanced neoplasia found at subsequent endoscopies compared with patients with non-advanced small adenoma(s) at index.
Patients with low-risk adenomas should be risk profiled. Those with risk factors, such as two adenomas, male sex, advanced adenomas at index procedure or strong family history, as well as those falling outside the BCSP enrolment age or who want colonoscopy surveillance should be offered a surveillance procedure at 5 years provided they are fit for the procedure. Everyone else could be considered for discharge with advice to return if symptomatic and encouraged to participate in the 2-yearly national faecal occult blood screening programme.
It is interesting to note that hot biopsy was the preferred polypectomy technique in over 50% of the adenomas detected at index procedure in our cohort. The current vogue is to use cold snare rather than hot biopsy for removing small polyps, but at the time of audit (i.e. April 2004 to April 2007) hot biopsy was still a popular technique.
A limitation of this study is that it assumes colonoscopy is 100% sensitive. We know this is not the case, however, even when intubation to the caecum is achieved. Miss rates for small adenomas are in the order of 25%–50%. Furthermore, around 6%–12% of larger adenomas (≥1 cm) and around 4% of cancers are missed at colonoscopy. It is, therefore, possible that some of the neoplastic lesions detected at the endoscopies that followed the index procedure were missed lesions as opposed to new lesions. However, this would only support our recommendations above and instead of offering surveillance to all low-risk patients' endoscopists would be better concentrating on performing meticulous examinations of the colon at the index procedure.
In summary, a significant proportion of low-risk postpolypectomy patients develop lower GI symptoms that necessitate colonoscopic investigation within 5 years of their index procedure—in our study, this was 17.2% of patients. For the remainder, the yield of advanced neoplasia at surveillance endoscopy was very low, especially for patients with only one small tubular or serrated adenoma. Only a small percentage of adenomas found at index procedure in this cohort were sessile-serrated adenomas (2%). This probably reflects the reduced awareness of the sessile-serrated adenoma at the period of the study. It is important to highlight that the current advice is that serrated polyps with dysplasia should be treated as high-risk lesions.
Discussion
As a consequence of the ever-increasing demand for colonoscopy, endoscopy units are under considerable pressure to meet the UK government's 18-week target time between patient referral and treatment. A 25% increase in demand was seen over 7 years prior to 2005. Introduction of the National Health Service BCSP in April 2006 has resulted in a further increase in the volume of colonoscopy. Therefore, ensuring that surveillance colonoscopy is restricted to those who are most likely to benefit has assumed greater importance. It is interesting to note that while the BCSP has adopted the BSG guideline there has been a small modification in that it does not include an option for a 5-year follow-up colonoscopy in the low-risk group. Our study shows that a minority of 'low-risk' patients (20.4%) actually have a per protocol surveillance colonoscopy. In those that do, we have found that the majority (72.5%) have no further adenomas detected at their surveillance endoscopy and that the yield for detecting advanced neoplasia at the 5-year surveillance colonoscopy is low (7.6%). No cancers were found at surveillance.
A previous UK study found that patients from whom only small (<1 cm) tubular adenomas were removed had no increased risk of developing colon cancer long term and the risk of rectal cancer was profoundly decreased compared with the unexamined population. These results were replicated by a similar study from the USA where no increased incidence of cancer was observed in 751 patients after removal of small (1 cm or less) colorectal polyps. The results from our study confirm that the benefits compared with the risks of surveillance colonoscopy are likely to be small in patients with only one to two small adenomas, and that follow-up colonoscopy, if undertaken at all, should be delayed by at least 5 years. The advanced neoplasia rate, including CRC, in our entire cohort was 6.6%, and we conclude that it is sensible to offer additional colonoscopies in the interim if the patient has new colorectal symptoms.
Some factors point towards higher risk of further adenomas and further advanced neoplasia. We found that male patients were significantly more likely to have further adenomas on subsequent endoscopies compared with female patients. However, it should be noted that a study by Erichsen et al found that in comparison with CRCs, interval cases were more likely to be women (54% vs 48%). We also found that patients with two small adenomas at index were significantly more likely to have advanced neoplasia at subsequent endoscopies compared with patients with only one small adenoma. Furthermore, we found that patients with advanced adenoma(s) at index (i.e. adenomas that had tubulovillous or villous histology or high-grade dysplasia) were significantly more likely to have advanced neoplasia found at subsequent endoscopies compared with patients with non-advanced small adenoma(s) at index.
Patients with low-risk adenomas should be risk profiled. Those with risk factors, such as two adenomas, male sex, advanced adenomas at index procedure or strong family history, as well as those falling outside the BCSP enrolment age or who want colonoscopy surveillance should be offered a surveillance procedure at 5 years provided they are fit for the procedure. Everyone else could be considered for discharge with advice to return if symptomatic and encouraged to participate in the 2-yearly national faecal occult blood screening programme.
It is interesting to note that hot biopsy was the preferred polypectomy technique in over 50% of the adenomas detected at index procedure in our cohort. The current vogue is to use cold snare rather than hot biopsy for removing small polyps, but at the time of audit (i.e. April 2004 to April 2007) hot biopsy was still a popular technique.
A limitation of this study is that it assumes colonoscopy is 100% sensitive. We know this is not the case, however, even when intubation to the caecum is achieved. Miss rates for small adenomas are in the order of 25%–50%. Furthermore, around 6%–12% of larger adenomas (≥1 cm) and around 4% of cancers are missed at colonoscopy. It is, therefore, possible that some of the neoplastic lesions detected at the endoscopies that followed the index procedure were missed lesions as opposed to new lesions. However, this would only support our recommendations above and instead of offering surveillance to all low-risk patients' endoscopists would be better concentrating on performing meticulous examinations of the colon at the index procedure.
In summary, a significant proportion of low-risk postpolypectomy patients develop lower GI symptoms that necessitate colonoscopic investigation within 5 years of their index procedure—in our study, this was 17.2% of patients. For the remainder, the yield of advanced neoplasia at surveillance endoscopy was very low, especially for patients with only one small tubular or serrated adenoma. Only a small percentage of adenomas found at index procedure in this cohort were sessile-serrated adenomas (2%). This probably reflects the reduced awareness of the sessile-serrated adenoma at the period of the study. It is important to highlight that the current advice is that serrated polyps with dysplasia should be treated as high-risk lesions.
