Protons Show Greater Relative Biological Effectiveness for Mammary Tumorigenesis with Higher ERα- and HER2-Positive Tumors Relative to γ-rays in APCMin/+ Mice

Exposure to ionizing radiation increases risk of breast cancer. Although proton radiation is encountered in outer space and in medicine, we do not fully understand breast cancer risks from protons owing to limited in vivo data. The purpose of this study was to comparatively assess the effects of γ-rays and protons on mammary tumorigenesis in APCMin/+ mice.Female APCMin/+ mice were exposed to 1 GeV protons (1.88 or 4.71 Gy) and 137Cs γ-rays (2 or...