Cardiac death after breast radiotherapy and the QUANTEC cardiac guidelines.

BACKGROUND

Breast/chest wall irradiation (RT) increases risk of cardiovascular death. International Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) guidelines state for partial heart irradiation a "V25Gy <10% will be associated with a <1% probability of cardiac mortality" in long-term follow-up after RT. We assessed whether women treated with breast/chest wall RT 10-years ago who died of cardiovascular disease (CVD) violated QUANTEC guidelines.

MATERIALS/METHODS

A population-based database identified all cardiovascular deaths in women with early-stage breast cancer <80 years, treated with adjuvant breast/chest wall RT from 2002 to 2006. Ten-year rate of cardiovascular death was calculated using a Kaplan-Meier method. Patients were matched on a 2:1 basis with controls that did not die of CVD. For left-sided cases, the heart and left anterior descending (LAD) artery were retrospectively delineated. Dose-volume histograms were calculated, and heart V25Gy compared to QUANTEC guidelines.

RESULTS

5249 eligible patients received breast/chest wall RT from 2002 to 2006: 76 (1.4% at 10-years) died of CVD by June 2015. Forty-two patients received left-sided RT (1.7% CVD death at 10-years), 34 right-sided RT (1.3% at 10-years). Heart V25Gy did not exceed 10% in any left-sided cases. No cardiac dosimetry parameter distinguished left-sided cases from controls.

CONCLUSIONS

QUANTEC guidelines were not violated in any patient that died of CVD after left-sided RT. The risk of radiation induced cardiac death at 10-years appears to be very low if MHD is <3.3 Gy and maximum LAD dose (EQD2

Déclaration de conflit d'intérêts

Dr. Beaton has nothing to disclose. A. Bergman has nothing to disclose. Dr. Nichol reports grants from Varian Medical Systems, outside the submitted work. M. Aparicio has nothing to disclose. Dr Wong has nothing to disclose. C. Speers has nothing to disclose. L. Gondara has nothing to disclose. Davis reports grants and personal fees from Pfizer, personal fees from Janssen, personal fees from Ferring, personal fees from TerSera, personal fees from Novartis, personal fees from Boehringer-Ingelheim, personal fees from Takeda, outside the submitted work. Dr. Tyldesley reports personal fees from Bayer and Janssen, outside the submitted work.