Colorectal Polyps in Childhood Cancer Survivors Treated with Radiation Therapy

Cancer survivors treated with abdominal or pelvic radiation therapy (RT) for childhood cancer have an increased risk of colorectal cancer. However, clinical guidelines are inconsistent on recommendations regarding the early initiation of screening in these patients due to the lack of supporting evidence that these patients pass through a pre-invasive phase, in which adenomatous polyps can be detected and removed.

To determine the prevalence of adenomatous polyps in cancer survivors treated with RT for childhood cancer; the prevalence in average-risk patients aged 17-49; and the prevalence in average-risk patients aged 50-75.

We conducted a retrospective study comparing the prevalence of adenomatous polyps among three patient groups: childhood cancer survivors aged 17-49 with prior RT who underwent colonoscopy screening from 2006 to 2017; age- and gender-matched patients in the average-risk population; and average-risk patients aged 50-75.

One hundred and forty-five patients were included in the study. The proportion of patients with adenomatous polyps in the cancer survivor group was significantly higher than that in the age- and gender-matched average-risk group (58.6 vs 17.2%, p = 0.00) and higher than the average-risk group aged 50-75 (58.6 vs 27.6%, p = 0.009). The prevalence of adenomas with high-risk features was higher in the survivor group compared to patients aged 50-75 (20.7 vs 3.5%, p = 0.015).

Cancer survivors treated with RT for childhood cancer have a higher prevalence of adenomatous polyps compared to the average-risk population. These findings support the early initiation of colonoscopy screening 10 years after radiation therapy, even in patients who have received RT doses below 30 Gy.