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

Abstract Objective 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. Methods 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. Results 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 39.8 years, respectively. The age distribution peaked at 30–40 years, followed by 40–50 years. Approximately 18% of testicular germ cell tumor patients were ≥50 years. The ages of the diffuse large B-cell lymphoma patients peaked at 70–80 years (mean 67.7 years). 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). Conclusion The testicular germ cell tumor patients’ mean age was nearly 40 years. 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.