The pooled OR from 4 studies involving 116 low-grade ovarian cancer patients and 148 high-grade ovarian cancer patients was shown in Table 2 (OR = 0.46, 95 % CI = 0.13–1.65, P = 0.233), suggesting that APC promoter hypermethylation was not significantly associated with tumor grade. This evidence concerns the gene APC and ovarian cancer.