Does Prophylactic Radiotherapy to avoid Gynecomastia in Patients with Prostate Cancer increase the risk of Breast Cancer?

Publication date: Available online 5 February 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Bjørg Y. Aksnessæther, Arne Solberg, Olbjørn H. Klepp, Tor Åge Myklebust, Eva Skovlund, Solveig Roth Hoff, Lars J. Vatten, Jo-Åsmund Lund
PurposeProstate cancer (PC) patients treated with antiandrogen monotherapy are offered prophylactic radiotherapy to the breast buds (PRT) to avoid gynecomastia. The aim of this study was to evaluate whether the risk of breast cancer (BC) in men with PC as their first cancer diagnosis, was influenced by PRT.Methods and MaterialsFrom the Norwegian Cancer Registry we collected data on all patients with PC as their first cancer diagnosis diagnosed between 1997- 2014. We registered all radiotherapy given to the patients in the same period, and the occurrence of BC diagnosed 3 months or more following the PC diagnosis. The histopathological diagnoses of all BC cases were collected. Subdistribution hazard ratios (SHR) for the risk of BC in PRT and non-PRT treated patients were estimated. A standardized incidence ratio (SIR) for BC was calculated by comparing our cohort to the standard male population.ResultsWe analyzed 59 169 patients with PC, whom 7864 (13.3%) had received PRT. Median follow-up time was 4 years. Three of 12 men diagnosed with BC had received PRT, and two of three were phyllodes tumors. The risk of BC was not statistically significantly different in patients given RT as compared to the non-RT patients, SHR 1.62 95% CI 0.41-5.62, adjusted for age and time of diagnosis. SIR was 0.996 95 % CI 0.57-1.75.ConclusionsIn this registry based study, we did not find an increased risk of BC in PC patients treated with PRT. The number of BC cases in our study was low, and the risk of secondary breast cancer following PRT seems to be negligible. The incidence of BC may, however rise with additional follow-up. It is noteworthy that two patients who had been treated with PRT were diagnosed with malignant phyllodes tumor, an extremely rare type of BC associated with gynecomastia.

Teaser

Nordic patients with prostate cancer receive prophylactic radiotherapy to the breast buds to avoid gynecomastia when treated with antiandrogen monotherapy. In this study with data from the Norwegian Cancer Registry, we did not find increased risk of breast cancer (BC) in irradiated patients compared to non-irradiated patients. It is noteworthy that in the RT group, there were two cases of malignant phyllodes breast tumor, an extremely rare type of BC associated with gynecomastia.


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