Expressions of DNA damage and repair-related genes such as ARTEMIS, Rad51, TP53BP1, BRAC1 were significantly enhanced after carbon ion beam combined with gemcitabine compared to carbon ion beam, X-ray alone or X-ray combined with gemcitabine, suggesting that carbon ion beam combined with chemotherapy may do more DNA damage to the cancer cells as a results activated homologous recombination pathway [51]. Here, RAD51 is linked to cancer.