Age related differences in primary testicular lymphoma: A population based cohort study

Primary testicular non-Hodgkin's lymphoma (PTL) is a very rare disease, comprising 1% of all non-Hodgkin's lymphoma and <5% of all cases of testicular tumors. With a median age at diagnosis of 67 years, PTL is the most common testicular malignancy in men aged >60 years. There is limited published data on PTL incidence and outcomes in younger patients. The aim of this study is to compare the clinical parameters and survival outcomes between the patients older and younger than 50.

The SEER database was queried for all patients diagnosed with PTL between 1983 and 2017. Data collected consisted of demographic, and clinical parameters, including staging, pathological assessments, and survival data. Patients were stratified according to their age and compared.

There was a total of 1,581 patients diagnosed with PTL between the year 2000 and 2017, of whom 215 (13.6%) were younger than 50 years old. The median age at diagnosis was 41 (interquartile range [IQR] 1-50), and 72 (IQR 51-95) years old for patients ≤50 and patients > 50 years of age, respectively. Comparison of younger and older patients detected similarities in disease laterality (92% vs. 94%, P = 0.38) and Ann Arbor stage I to II at diagnosis (76% vs. 75%, P = 0.59). The most common diffuse large B-cell lymphoma (DLBCL) subtype was more common in older patients (61% vs. 87%, P < 0.001). Radical orchiectomy (71% vs. 79%, P = 0.004) and radiation treatment (40% vs. 37%, P = 0.49) rates were comparable between both groups. However, a higher proportion of younger patients underwent chemotherapy (83% vs. 72%, P < 0.001). Patients ≤50 and >50 years old had a hazard ratio (HR) of 0.63 (95% CI: 0.57-0.71) and 0.34 (95% CI: 0.31-0.37), respectively, for 10-year OS with a median survival time for patients >50 of 5.75 years (95% CI: 5.25-6.33), P < 0.001. Patients ≤50 years old had a HR of 0.33 (95% CI: 0.26-0.40) compared to HR of 0.40 (95% CI: 0.37-0.43) in patients >50 years old for cumulative disease-specific mortality (DSM, P = 0.0204). Age >50 years was associated with worse DSM with a HR of 1.39 (95% CI: 1.05- 1.86, P = 0.024). Ann Arbor stage II and higher was also associated with worse DSM, while undergoing surgery, radiotherapy, and chemotherapy were associated with improved DSM.

PTL is the most common testicular malignancy in men older than 60 years of age, but more than a quarter of the patients are younger than 60 and more than 13% are ≤50 years. Younger patients are more likely to receive chemotherapy and radiation, and overall do better in terms of DSM. Being younger, having a lower Ann Arbor stage and being treated with chemotherapy and radiotherapy increase the chances of survival.