Endosalpingiosis is a disease characterized by ectopic epithelium that looks similar to the fallopian tubes. However, it is not well understood. It’s been called a “malignancy-associated accidental pathology finding” and a “disease related to endometriosis.” This research aimed to examine endosalpingiosis (ES) and endometriosis (EM) to see if one was more strongly linked to gynecologic cancer. This is a case-control study of individuals at 3 connected academic hospitals diagnosed with endosalpingiosis or endometriosis histologically between 2000 and 2020. All patients with ES were included, and a 1:1 match was made to find a group of EM patients with similar characteristics. Researchers gathered clinical and demographic information and ran the numbers. There were a total of 967 patients, 515 ES, and 452 EM. The median age of ES patients was 52 years old, while that of EM patients was 48 (P<0.001). A higher percentage of patients in the ES group were diagnosed with cancer before surgery (40.1% vs. 18.1%, P<0.001), and this difference continued in a sub-analysis omitting patients with confirmed or suspected malignancy (20.9% vs. 5.6%, P<0.001). Comparing patients with and without ES, the 10-year survival rate was 77.0% vs. 90.5% (P<0.001). Multivariable analysis showed that after controlling for confounding factors, patients with ES had a higher risk of mortality (OR = 1.69, P=0.017) and higher odds of being diagnosed with cancer during surgery (OR = 2.48, P<0.001). Multivariate and subgroup studies confirmed the correlation between endosalpingiosis and malignancy, which was observed in 40% of cases. Longitudinal studies and investigations into molecular links between ES and cancer are planned for the future.