The Impact of Laterality on the Incidence and Prognosis of Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the most common type of ovarian cancer, and its mortality rate is the highest among gynecological malignancies. Despite numerous factors being linked to the prognosis of EOC, the impact of ovarian laterality has received limited attention. In this study, we comprehensively examined the effects of laterality (left-right and bilateral-unilateral) on the incidence and prognosis of EOC, with a particular focus on different subtypes. By utilizing a large clinical database, we found that laterality differences primarily existed between unilateral and bilateral cases in terms of both incidence and prognosis. Specifically, unilateral tumour development was predominantly observed in patients with clear cell, endometrioid, and mucinous ovarian cancer subtypes, while bilateral involvement was more common in serous ovarian cancer. Laterality differences, reflecting disparities between the left and right sides, were primarily observed in various stages of the overall population and within specific EOC subtypes. Specifically, significant differences in EOC incidence between the left and right sides at different stages were observed in the overall population, as well as in clear cell, endometrioid, and serous ovarian cancer subtypes. Although no significant differences in the incidence rate between the left and right sides were noted for mucinous ovarian cancer, the prognosis was substantially better on the right side compared to the left side. These findings underscore the importance of considering ovarian laterality, both in terms of left-right and bilateral-unilateral aspects, as a critical factor associated with the incidence and prognosis of EOC. Therefore, it should be taken into account in clinical practice, particularly in the context of different tumour stages and subtypes of EOC.