PGR and ovarian serous adenocarcinoma: In the subgroup analysis by histological type, a better OS was strongly linked to progesterone receptor expression in unclassified ovarian cancer (n = 19, HR = 0.79, 95% CI = 0.64 to 0.98, P = 0.034, I2 = 73.6%) while there was no significant association in serous ovarian cancer (n = 7, HR = 0.85, 95% CI = 0.69 to 1.06, P = 0.146, I2 = 60.9%).