Patients with unilateral ovarian cancer have similar outcomes whether the tumor is located on the left or right side of the body, but those with bilateral tumors have worse prognosis, according to a study published in Cancer Treatment and Research Communications

The population-based study included 10,177 patients with ovarian cancer diagnosed between 2004 and 2016. Tumors were right-sided in 36.7% of cases and left-sided in 36.9% of cases. In 26.4% of cases, tumors were bilateral.

The entire cohort had a median overall survival (OS) of 77 months, but patients with bilateral tumors had a median OS of 34 months.

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Patients with bilateral tumors had a 45.3% higher risk of death when compared with patients who had unilateral tumors (hazard ratio [HR], 1.453; 95% CI, 1.410-1.497; P <.001). The relative increase in risk was attenuated, at 8.7%, in a multivariate analysis (HR, 1.087; 95% CI, 1.043-1.136; P =.02).

Among patients with unilateral tumors, the risk of death was similar regardless of whether the tumor was left- or right-sided (HR, 0.958; 95% CI, 0.888-1.033; P =.268). There was also no association between sidedness and prognosis of cancers of different stages.

“Our real-world study demonstrated that impact of tumor sidedness has no prognostic implication …, but bilateral OCs [ovarian cancers] might be marginally more prognostically unfavorable,” the researchers wrote. They added that prospective validation may be needed to confirm these findings.


El Bairi K, Trapani D, Le Page C, Saad A, Al Jarroudi O, Afqira S. Exploring the prognostic impact of tumor sidedness in ovarian cancer: A population-based survival analysis of over 10,000 patients. Cancer Treat Res Comm. 2022;33:100625. doi:10.1016/j.ctarc.2022.100625