Hodgkin lymphoma (HL) patients treated with subdiaphragmatic radiation and procarbazine have an increased risk of developing colorectal cancer (CRC), according to results of a case-control study published in JAMA Oncology.

Researchers found that subdiaphragmatic radiation and procarbazine were each associated with an increased risk of CRC. When the 2 treatments were given together, the risk of CRC was even greater.

The researchers studied 316 patients who had been diagnosed with HL between 1964 and 2000. All patients received treatment with radiation therapy (RT) and/or chemotherapy. 

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HL survivors who did not develop CRC served as the control cohort and were matched to cases based on sex, age at HL diagnosis, and date of HL diagnosis. 

There were 78 patients who developed CRC. The median time between HL diagnosis and CRC diagnosis was 25.7 years. Most patients with CRC were diagnosed between ages 50 and 64 years (63%). CRC diagnosis most commonly occurred from 15 to 34 years after HL diagnosis (67%). The majority of cases were adenocarcinoma (60%).

In a univariable analysis, subdiaphragmatic RT was associated with a significantly increased risk of CRC (rate ratio [RR], 2.4; 95% CI, 1.4-4.1). 

The combination of chemotherapy with subdiaphragmatic RT further increased the risk of CRC (RR, 7.4; 95% CI, 2.3-23.7). However, there was no association between CRC risk and chemotherapy alone or chemotherapy with supradiaphragmatic RT.

Procarbazine at a dose of 8.4 g/m2 or more was associated with an increased risk of CRC (RR, 2.5; 95% CI, 1.3-5.0). The combination of RT and procarbazine further increased the risk of CRC when the RT dose to the whole large bowel was 10 Gy or higher. This was true if the procarbazine dose was 4.2 g/m2 or less (RR, 2.1; 95% CI, 1.0-4.8) or higher than 4.2 g/m2 (RR, 5.2; 95% CI, 2.2-12.3).

“This evidence enables individualized estimation of colorectal cancer risk and selection of the optimal treatment strategy for patients who are treated with subdiaphragmatic RT,” the researchers concluded. “These findings also emphasize the need for clinicians to identify HL survivors previously treated with subdiaphragmatic RT and procarbazine for whom colorectal cancer screening should be considered.”


Geurts YM, Shakir R, Ntentas G, et al. Association of radiation and procarbazine dose with risk of colorectal cancer among survivors of Hodgkin lymphoma. JAMA Oncol. Published online February 2, 2023. doi:10.1001/jamaoncol.2022.7153

This article originally appeared on Cancer Therapy Advisor