Relationship between the precursors of high grade serous ovarian cancer and patient characteristics: decreased incidence of the p53 signature in pregnant women

OBJECTIVE: To investigate the relationship between the precursors of high grade serous ovarian cancer (HGSOC) and the characteristics of patients with a low HGSOC risk in terms of the effects of pregnancy. METHODS: We prospectively examined consecutive cases in which the bilateral fallopian tubes were removed during benign gynecological or obstetric surgery and assessed the relationship between the patient characteristics, including parity and pregnancy, and the incidence of HGSOC precursors. All the fallopian tubes were examined by applying the Sectioning and Extensively Examining the Fimbriated End (SEE-FIM) Protocol. RESULTS: Of the 113 patients enrolled, 67 were gynecological and 46 were obstetric. The p53 signature was identified in 21 patients. No other precursors were identified. In a comparison of the p53 signature-positive and negative groups, parous women and pregnant women were significantly fewer in the p53 signature-positive group (53% vs. 86%, p=0.002, 10% vs. 47%, p=0.001, respectively). Current pregnancy was also associated with a significantly lower incidence of the p53 signature after multivariate adjustment (odds ratio [OR]=0.112; 95% confidence interval [95% CI]=0.017–0.731; p=0.022). Among gynecological patients, parous women were fewer in the p53 signature-positive group on univariate (47% vs. 73%, p=0.047) and multivariate analysis (OR=0.252; 95% CI=0.069–0.911; p=0.036). No other characteristics were associated with p53 signature positivity. CONCLUSIONS: The incidence of the p53 signature was significantly lower in parous women and pregnant women. This decreased incidence of early phase serous carcinogenesis may be one of the possible mechanisms underlying HGSOC risk reduction among parous women.