Increased pancreatic cancer risk following radiotherapy for testicular cancer
Menée en Norvège à partir de données portant sur 23 982 patients ayant survécu 5 ans à un cancer du testicule diagnostiqué entre 1974 et 1991, cette étude cas-témoins évalue le risque de cancer du pancréas après une radiothérapie, en fonction des doses reçues
Background: Pancreatic cancer risk is elevated among testicular cancer (TC) survivors. However, the roles of specific treatments are unclear. Methods: Among 23 982 5-year TC survivors diagnosed during 1947–1991, doses from radiotherapy to the pancreas were estimated for 80 pancreatic cancer patients and 145 matched controls. Chemotherapy details were recorded. Logistic regression was used to estimate odds ratios (ORs). Results: Cumulative incidence of second primary pancreatic cancer was 1.1% at 30 years after TC diagnosis. Radiotherapy (72 (90%) cases and 115 (80%) controls) was associated with a 2.9-fold (95% confidence interval (CI) 1.0–7.8) increased risk. The OR increased linearly by 0.12 per Gy to the pancreas (P-trend<0.001), with an OR of 4.6 (95% CI 1.9–11.0) for greater than or equal to25 Gy vs <25 Gy. Radiation-related risks remained elevated greater than or equal to20 years after TC diagnosis (P=0.020). The risk increased with the number of cycles of chemotherapy with alkylating or platinum agents (P=0.057), although only one case was exposed to platinum. Conclusions: A dose–response relationship exists between radiation to the pancreas and subsequent cancer risk, and persists for over 20 years. These excesses, although small, should be considered when radiotherapy with exposure to the pancreas is considered for newly diagnosed patients. Additional data are needed on the role of chemotherapy.