Prevalence of Primary Testicular Germ Cell Cancer in Young Adults
Testicular germ cell cancer is the most common solid malignancy in young adult males aged 15-35 years, with a crude incidence rate of approximately 4.8 per 100,000 males per year in Europe, and approximately 10,000 new cases diagnosed annually in the United States. 1, 2
Epidemiologic Data
Age distribution: The mean age at diagnosis is 33 years, with testicular cancer representing the most common solid malignancy in males aged 15-40 years 2, 3
Proportion of germ cell tumors: Between 90-95% of all testicular cancers are germ cell tumors (GCTs), with the remaining 5-10% being non-germ cell malignancies 2, 3
Histologic breakdown: Approximately 60% of testicular GCTs are mixed or non-seminomatous tumors, while the remaining 40% are seminomas 1
Bilateral disease: Approximately 2-3% of patients present with bilateral testicular tumors, either synchronously or metachronously 1
Stage at Presentation
The stage distribution at diagnosis provides important context for understanding disease burden 2:
- Stage I (localized to testicle): 70-75% of patients
- Stage II (retroperitoneal lymph node metastases only): 20% of patients
- Stage III (widely metastatic): 10% of patients
Racial and Ethnic Disparities
Significant racial disparities exist in testicular cancer incidence 1:
- White males have the highest incidence, approximately five times higher than Black males 1
- Asian Americans and Pacific Islanders have slightly higher incidence than Black males 1
- Hispanic males have an incidence roughly 60% of that in white males 1
- Native Americans fall between Hispanic and white populations 1
Important caveat: While white males have higher incidence, Black males are more likely to present with regional or distant metastatic disease and have lower 5-year survival rates (85% vs 96% for regional disease; 56% vs 72% for distant disease) 1
Contralateral Testicular Risk
- Approximately 5% of testicular cancer patients harbor germ cell neoplasia in situ (GCNIS) in the contralateral testis 1
- The highest risk (approximately 30%) occurs in men with testicular atrophy (volume <12 ml) and age <40 years 1
- The 20-year crude cumulative incidence of metachronous contralateral GCT is 5.4% after surgery only, reduced to 3.2% with three or more cycles of cisplatin-based chemotherapy 1
Extragonadal Presentations
A minority of patients present with primary extragonadal germ cell tumors 1:
- Primary sites include retroperitoneum or mediastinum 1
- Approximately one-third of these patients harbor intratubular germ cell neoplasia (GCNIS) in the testis 1
- Another third show scar tissue indicating a "burned out" testicular tumor 1
- Only one-third have definitively primary extragonadal germ cell tumors 1