From the Research
Patients with a history of anal cancer should undergo a baseline colonoscopy at the time of diagnosis, followed by surveillance colonoscopies every 5 years if the initial examination is normal. This recommendation is based on the increased risk of colorectal neoplasia in patients with anal cancer, particularly those who have received radiation therapy to the pelvis 1. The baseline colonoscopy is important to rule out synchronous colorectal lesions, while the 5-year surveillance interval helps detect metachronous lesions that may develop later.
Key Considerations
- For patients who have received pelvic radiation, more frequent surveillance may be considered due to the increased risk of radiation proctitis and secondary malignancies.
- The colonoscopy preparation and procedure are standard, typically using a split-dose bowel preparation such as polyethylene glycol solution.
- If polyps or other abnormalities are found during any colonoscopy, the surveillance interval may need to be shortened based on the findings.
- Additionally, patients should be monitored for symptoms such as rectal bleeding, change in bowel habits, or abdominal pain between scheduled colonoscopies, as these may warrant earlier evaluation.
Evidence Summary
The most recent and highest quality study on colorectal cancer screening recommendations is from 2017, which suggests that colonoscopy every 10 years is a first-tier test for average-risk individuals 2. However, for patients with a history of anal cancer, a more tailored approach is necessary, taking into account their increased risk of colorectal neoplasia. A study from 2018 provides guidance on colorectal cancer screening and surveillance in individuals at increased risk, including those with a personal or family history of advanced adenomas or colorectal cancer 3.
Clinical Implications
In clinical practice, it is essential to prioritize the individual's risk factors and medical history when determining the appropriate colonoscopy surveillance interval. For patients with a history of anal cancer, a baseline colonoscopy at the time of diagnosis, followed by surveillance colonoscopies every 5 years, is a reasonable approach. However, this interval may need to be adjusted based on individual factors, such as the presence of pelvic radiation or abnormal findings on previous colonoscopies.