Exposure to abdominal radiation for childhood cancer has been associated with an increased risk of gastrointestinal polyps and neoplasia. These patients have a similar risk of developing colorectal cancer (CRC) as those with two or more first-degree relatives with CRC. There has been an inconsistency in clinical practice guidelines, partly due to limited evidence that treatment-associated colorectal cancer has a preceding screen-detectable phase. The previous recommendation from the Children’s Oncology Group (COG) for starting screening was from age 35, but guidelines have been revised to recommend 3-yearly stool test and 5-yearly colonoscopy from age 30 (or 5 years after radiation, whichever occurs last). We describe a case series from one centre of 12 survivors of childhood cancer with gastrointestinal polyps detected on gastroscopy/colonoscopy, with a median age of 26 years (range 20-41 years). Most of these had preneoplastic lesions (tubular adenomata). The median age of radiation exposure was 6 years of age, and the time to development of polyps was a median of 26 years. In all these reported cases, their radiation was not direct abdominal radiation for abdominal/pelvic malignancies, but rather craniospinal radiation or total body irradiation prior to bone marrow transplant. Three of these individuals were found to have colorectal malignancy (ages 20, 28 and 36), one of whom died from metastatic bowel cancer. One was confirmed to have Turcot syndrome, a rare association between primary brain tumours and colorectal cancer to be considered in all cases with medulloblastoma. A small number of multicentre case series (and one prospective study) are reported in the literature to date, emphasizing the significance of this number from one centre. Teepen et al (2018) described 17 childhood cancer survivors with colorectal adenomas before the age 30, in addition to Au et al (2018) reporting 12 individuals under the age of 35. It is imperative to increase awareness about bowel cancer risk post radiation and to include screening as a regular part of late effects care. Even with the revised guidelines, most of our described cases would be detected late, hence screening recommendations need to be adhered to, regarding commencing surveillance from 5 years post radiation, to avoid missing the under 30 year age group.
15 Sep 2022 - 17 Sep 2022