The overall OR from 7 studies including 193 serous carcinoma and 217 non-serous carcinoma cases suggested that APC promoter hypermethylation was significantly correlated with tumor histology (OR = 0.56, 95 % CI = 0.35–0.91, P = 0.02), and it was lower in serous carcinoma than in non-serous carcinoma (Fig. 4). The gene discussed is APC; the disease is serous adenocarcinoma.