Radiotherapy-related dose and irradiated volume effects on breast cancer risk among Hodgkin lymphoma survivors
Menée auprès de 464 témoins et 173 personnes ayant survécu 5 ans à un lymphome de Hodgkin, cette étude analyse l'effet de la dose de radiothérapie thoracique reçue sur le risque de cancer du sein
Breast cancer (BC) risk is increased among Hodgkin lymphoma (HL) survivors treated with chest radiotherapy. Case-control studies showed a linear radiation dose-response relationship for estimated dose to the breast tumor location. However, these relative risks cannot be used for absolute risk prediction of BC anywhere in the breasts. Furthermore, the independent and joint effects of radiation dose and irradiated volumes are unclear. Therefore, we examined the effects of mean breast dose and various dose-volume parameters on BC risk in HL patients.We conducted a nested case-control study of BC among five-year HL survivors (173 cases, 464 matched controls). Dose-volume histograms (DVHs) were obtained from reconstructed voxel-based three-dimensional dose distributions. Summary parameters of DVH were studied next to mean and median breast dose, Gini index and the new dose metric mean absolute difference (MAD) of dose, using categorical and linear excess odds ratio (EOR) models. Interactions between dose-volume parameters and mean dose were also examined.Statistically significant linear dose-response relationships were observed for mean breast dose (EOR/Gy: 0.19; 95% confidence interval [CI]: 0.05 to 1.06) and median dose (EOR/Gy: 0.06; 95% CI: 0.02 to 0.19), with no statistically significant curvature. All metrics except Gini and MAD were positively correlated with each other. These metrics all showed similar patterns of dose-response that were no longer statistically significant when adjusting for mean dose. No statistically significant modification of the effect of mean dose was observed.Mean breast dose predicts subsequent BC risk in long-term HL survivors.