Recent malignant testicular tumor trend in Japan, a country with an aging population: a large-scale study of 2012-2015 hospital-based cancer registry data.

Abstract

Japan's national database of hospital-based cancer registries is estimated to cover ~67% of all new cancer cases. Using this database, we analyzed the characteristics of the recently diagnosed testicular malignancy. We obtained data for 6510 adult testicular malignancy patients diagnosed in 2012-2015. The distributions of patient ages, histological diagnoses and testicular germ cell tumor hospital care volumes were determined. The most common histology was seminoma (60.3% of all testicular malignancies), followed by non-seminoma (24.1%) and diffuse large B-cell lymphoma (13.1%). The median and mean ages of the testicular germ cell tumor patients were high at 38 and 39.8years, respectively. The age distribution peaked at 30-40years, followed by 40-50years. Approximately 18% of testicular germ cell tumor patients were ≥50years. The ages of the diffuse large B-cell lymphoma patients peaked at 70-80years (mean 67.7years). When the analysis was limited to the testicular germ cell tumor patients who received first-course cancer treatment at the participating hospitals, the number of high-volume hospitals with ≥20 testicular germ cell tumor care volume was limited to 61 (10.0% of the 605 hospitals that treated ≥1 testicular germ cell tumor patient). However, when the patients who changed hospitals during treatment or relapsed after treatment completion were analyzed together, the number of high-volume hospitals increased to 104 (17.0% of 612 hospitals). The testicular germ cell tumor patients' mean age was nearly 40years. The proportions of older testicular germ cell tumor patients and diffuse large B-cell lymphoma patients were higher than previously thought. The reasons for this trend are unknown, but it is important to address the trend identified herein in a country with a super-aging population.