A propensity score-matched analysis of oncological outcome after systemic therapy for stage IV colorectal cancer: Impact of synchronous ovarian metastases

The reported incidence of synchronous and metachronous ovarian metastases (OM) from colorectal cancer (CRC) is ~3.4%. OM from CRC are often considered sanctuary sites due to their lower sensitivity to systemic treatment. It has thus been hypothesized that the presence of OM decreases overall survival. Therefore, the purpose of our study was to evaluate the impact of synchronous OM on overall survival in female patients with stage IV CRC treated with systemic therapy alone with palliative intent. The present study used data from the Netherlands Cancer Registry and included female CRC patients with synchronous systemic metastases who were treated with systemic therapy between 2008 and 2018. A subsample was created using propensity score matching to create comparable groups. Propensity scores were determined using a logistic regression model in which the dependent variable was the presence of OM and the independent variables were the variables that differed significantly between both groups. Our study included 5253 patients with stage IV CRC that received systemic therapy. Among these patients, 161 (3%) had OM while 5092 (97%) had extra-ovarian metastases only. Three-year overall survival rates did not show a significant difference between patients with OM compared to patients without ovarian metastases. Moreover, the propensity score-matched analysis showed that the presence of OM in patients treated with systemic therapy for stage IV CRC disease was not associated with decreased 3-year overall survival. However, the results of the present study should be interpreted with caution, due to its observational character and used selection criteria.