Increased risk of second cancer among patients with ovarian borderline tumors

Several studies have demonstrated a higher risk of colorectal and breast cancers subsequent to invasive ovarian cancer. Such risk has not been investigated for ovarian borderline tumors. We aim to evaluate the risk of subsequent cancer occurrence among patients with borderline ovarian tumors in a population-based setting.

We identified 171 patients with a diagnosis of borderline ovarian tumors recorded at the Geneva Cancer Registry, Switzerland. We calculated age and period standardized incidence ratios (SIR) of second tumor occurrence by dividing the number of observed cases by the number of expected cases in the cohort, using cancer incidence rates of the general female population.

The risk of developing second cancer was 1.85-fold (95% Confidence Interval [CI]: 1.10-2.92, n=16) higher among women with borderline ovarian tumors compared to that expected in the general population. The excess of risk primarily concerned colorectal cancer (SIR: 3.97, CI: 1.38-12.95, n=5) and breast cancer (SIR: 2.09, CI: 0.84-4.31, n=7), but the latter result was not statistically significant (p=0.09). The increased risk of developing second cancer was mainly observed among patients diagnosed with ovarian borderline tumors occurring before the age of 50. These results were not explained by surveillance bias or by metastasis from one site to another.

Women with ovarian borderline tumors have an increased risk of developing secondary cancer, particularly colorectal cancer. These results point to potential common risk factors for these tumors and ask for close surveillance of patients with borderline ovarian tumors.