To assess the mechanism of the effects of olaparib on tumor invasion to the mandible, we analyzed the protein levels of factors related to osteoclast activation, RANK and RANKL, and factors related to EMT, E-cadherin, N-cadherin, Twist, SNAIL, and PARP1, using HSC-2-derived tumors resected on day 60. This evidence concerns the gene TWIST1 and neoplasm.