Background: A contralateral tumor occurs in 3.5-5% of men diagnosed with testicular germ cell cancer (TGCC). Biopsy of the contralateral testis may detect intratubular germ cell neoplasia ITGCNU, a precursor of TGCC. Biopsy of the contralateral testis to detect ITGCNU is controversial. If adjuvant chemotherapy (ACT) protects against bilateral cancer is debated.
Material and methods: A total of 1003 patients with clinical stage I (CS I) non-seminomatous testicular germ cell cancer (NSGCT) were included in two prospective, population-based protocols. Fifteen patients were excluded. Treatment was either adjuvant chemotherapy (n = 494), or surveillance (n = 494). Contralateral testicular biopsy was recommended for all patients, but was performed only in 282 patients. In case of ITGCNU radiotherapy (RT) to 16 Gy was recommended.
Results: During a follow-up of 8.3 years, 31 (3.6%) patients developed contralateral TGCC. ITGCNU was detected in 3.2% (9/282) of biopsied patients. The incidence of bilateral TGCC was similar following ACT, 2.5% (11/494), and surveillance, 3.4% (13/494), p = 0.41. Young age was a risk factor for metachronous TGCC (HR 0.93; 95% CI 0.88-0.99, p = 0.02). In total 2.2% (6/273) of patients without ITGCNU in the biopsy developed contralateral TGCC. One irradiated patient developed contralateral cancer, and one developed contralateral tumor before RT was given.
Conclusion: ACT did not reduce the incidence of contralateral TGCC. Young patients had the highest risk of developing contralateral TGCC. The proportion of false negatives biopsies was higher than reported in earlier trials, but this may in part be related to patient selection, single biopsies and lack of mandatory immunohistochemistry.