The effects of a prior malignancy on the survival of patients with ovarian cancer: a population-based study

Background: With the improvement in the prognostic outcomes of multiple malignancies, the population of cancer survivors is growing rapidly and is at higher risk of developing secondary ovarian cancer. However, the prevalence and clinical outcomes of prior cancer among newly diagnosed ovarian cancer patients remain unknown. Methods: Patients diagnosed with ovarian cancer between 2004 and 2015 were identified using the Surveillance, Epidemiology, and End Results database. Patients were divided into two groups based on whether there was a prior malignancy. A multivariate Cox regression analysis was used to calculate all-cause and ovarian-specific survival. Furthermore, we conducted subgroup survival analyses of patients stratified by previous cancer site to explore the associations between prior cancer site and survival outcomes. Results: A total of 52,182 patients with primary ovarian cancer were identified, and 3.6% (n=1,860) had a documented prior malignancy. In multivariate analyses, patients with prior malignancies had a worse all-cause and ovarian cancer-specific prognosis than those without. In subset analyses, patients with a history of thyroid cancer had a better all-cause and ovarian cancer-specific prognosis, and patients with prior colorectal, urinary system, skin, lung, haematologic and stomach cancers were at risk of decreased survival compared to that of patients without a prior cancer. Conclusions: Prior malignancy has an adverse impact on the survival of patients with ovarian cancer, and the impact on prognostic outcomes varies by different prior cancer sites. The inconsistent survival effects of previous malignancies should be considered in clinical trial design and recruitment.