Clinicopathological characteristics and survival outcomes for testicular choriocarcinoma and non-testicular choriocarcinoma: A SEER database analysis.

Abstract

e17026 Background: Primary Choriocarcinoma (CC) is a rare germ cell tumor that can occur in males. The most common primary site in men is the testis. It can occur in extragonadal sites such as the mediastinum, retroperitoneum, lungs or brain. The clinical and prognostic differences between testicular CC and non-testicular CC are unclear. We aim to study the differences in clinical features, prognostic factors, and outcomes between the two subtypes of CC. Methods: We analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database for patients diagnosed with pure CC between 2000 and 2018. Patients with a previous history of cancer or with other concurrent malignancies were excluded. These patients were divided into two groups: testicular and non-testicular CC. The clinicopathological features of each group were compared using chi-square tests. Kaplan-Meier estimator, log-rank tests, and Cox proportional hazard regression were used to identify prognostic factors over overall survival (OS) and cancer-specific survival (CSS). Results: The study included 363 patients, with 270 (74.4%) patients classified as having testicular CC and 93 (25.6%) as having non-testicular CC. The results showed that testicular CC was more likely to occur in white patients, be bilateral in distribution, have a smaller size, and be in more advanced SEER stages compared to non-testicular CC. Additionally, testicular CC patients were more likely to undergo surgical treatment, but not radiation. Testicular CC patients had a better OS and CSS (HR = 0.52, 95% CI: 0.38-0.71 and HR = 0.52, 95% CI: 0.37-0.71, respectively) compared with non-testicular CC. Our Cox multivariate analyses for OS and CSS identified the following independent prognostic factors for testicular CC: localized stage, surgery, tumor size ≥ 4cm, radiotherapy, and chemotherapy. Interestingly, the use of radiotherapy was actually associated with poor OS and CSS (HR = 1.8, 95% CI: 1.17-2.85 and HR = 1.7, 95% CI: 1.05-2.73, respectively). For non-testicular CC, the independent prognostic factors for OS and CSS were age ≥ 30 years, non-paired site, regional stage, surgery, and chemotherapy. Conclusions: Our study provides important insights into the differences between testicular and non-testicular CC. The use of radiotherapy is generally not recommended in testicular CC which might explain its bad prognostic effect as these patients might be naturally at higher risk of dying. However, the bad poor prognosis of patients using radiotherapy persisted even after controlling for other important prognostic factors. Further studies with larger sample sizes are needed to validate and build upon these findings, but our results provide a starting point for a better understanding of such rare cancer.