Endocrine Abstracts

Background: Bilateral testicular germ cell tumors (B-TCGT) are reported as rare findings (incidence 1-8%) and can be distinguish in synchronous (sB-TCGT) (recurrence within 3 months) and metachronous (mB-TCGT) (recurrence after 3 months). Risk factors of relapse are still underexplored. The aim of our study was to identify clinical, biochemical and radiological risk factors for the onset of a second tumor in a wide cohort of TGCT patients.

Materials and Methods: This is a retrospective, monocentric case-control study including TGCT-patients who performed regular ultrasound (US) follow-up at the TestisUnit of Policlinico Umberto I, Rome, Italy, from 2006 to 2021. Testicular US, post-orchiectomy hormones and semen analysis were all performed in our institution. Data from serum tumor markers (STM), histological examination, post-orchiectomy treatments and follow-up time were recorded. Patients with mB-TGCTs were compared with unilateral TGCT patients with a follow-up greater than the median time-to-onset of the second tumor, which represented our control group (u-TGCT). The statistical analysis was carried out with non-parametric tests.

Results: The final population included 243 patients with TGCT: 158 (65%) with seminoma, 85 (35%) with non-seminoma. Among B-TGCT, 11 were sB-TGCT and 36 mB-TGCT. Among mB-TGCT, the median time-to-onset of the second tumor was 56.5 months [IQR 28;138 (range 8-211)]. u-TGCT group included 100 patients. mB-TGCT compared to u-TGCT showed a residual testicle with lower volume [10.4mL (8.9;13) vs. 16.3mL (12.0;19.1), P<0.001], more inhomogeneous echotexture [27/36 (75%) vs 50/100 (50%), P=0.003] and testicular microlithiasis (TML) [28/36 (77.7%) vs 24/100 (24%), P<0.001]. mB-TGCT presented higher gonadotropin values [FSH 12.1 mIU/ml (6.0;34.5) vs 5.9 mIU/ml (2.8;9.3), P=0.003; LH 6.5 mIU/ml (2.8;13.4) vs 3.4 mIU/ml (1.9;5.2), P=0.014] with similar testosterone levels (P=0.862) and lower sperm concentration [6x10⁶/ml (0.1-32) vs 21x10⁶/ml (5.7-48), P=0.045]. No differences were found in the two groups for clinical history, histological features, STM and post-orchiectomy treatments. Kaplan-Meier curves confirmed that patients with contralateral testicular volume <12 mL (P=0.023), inhomogeneous echotexture (P=0.011) and TML (P<0.001) had a higher cumulative risk of development of a second tumor. Logistic regression analysis showed that the presence of TML was the best independent predictor (OR 13.992, 95%CI:1.96-99.897, P=0.009).

Conclusions: B-TCGT is not such a rare event. Patients with a low volume surviving testicle, with inhomogeneous echotexture or TML have a cumulative increased risk of developing a second tumor. US follow-up is mandatory and a complete morpho-functional evaluation of the contralateral testis is essential to set up a personalized program.