Malignant testicular neoplasms can arise from either the germ cells or sex-cord stromal cells, with the former comprising approximately 95% of all testicular cancers (Table 1). Germ cell tumors may contain a single histology or a mix of multiple histologies. For clinical decision making, testicular tumors are categorized as either pure seminoma (no nonseminomatous elements present) or nonseminomatous germ cell tumors (NSGCT). The prevalence of seminoma and NSGCT is roughly equal. If a testicular tumor contains both seminomatous and nonseminomatous components, it is called a mixed germ cell tumor. Because of similarities in biological behavior, the approach to treatment of mixed germ cell tumors is similar to that for NSGCT.
The key points to remember for testicular cancer are:
- With early diagnosis and aggressive multidisciplinary therapy, the overwhelming majority of patients can be cured;
- Specialized care is often critical and affects outcomes; and
- Survivorship, or post-treatment care, is very important for these patients, as they often have lifespan of several decades and a unique set of short- and long-term treatment-related complications.
Developmental Biology and Genetics
The developmental biology of germ cells and germ cell neoplasms is beyond the scope of this review, and interested readers are recommended to refer to pertinent articles on the topic.1,2 A characteristic genetic marker of all germ cell tumors is an isochromosome of the short arm of chromosome 12, i(12p). This is present in testicular tumors regardless of histologic subtype as well as in carcinoma-in-situ. In germ cell tumors without i(12p) karyotype, excess 12p genetic material consisting of repetitive segments has been found, suggesting that this is an early and potentially critical change in oncogenesis.3 Several recent studies have revealed a diverse genomic landscape in testicular cancers, including KIT, KRAS and NRAS mutations in addition to a hyperdiploid karyotype.4,5
Evaluation and Diagnosis
A 23-year-old Caucasian man presents to a primary care clinic for a pre-employment history and physical exam. He reports testicular pain on the sexually transmitted infections screening questionnaire. On examination, the physician finds a firm, mobile, minimally-tender, 1.5-cm mass in the inferior aspect of left testicle. No contralateral testicular mass or inguinal lymphadenopathy is noted, and a detailed physical exam is otherwise unremarkable. The physician immediately orders an ultrasound of the testicles, which shows a 1.5-cm hypoechoic mass in the inferior aspect of the left testicle, with an unremarkable contralateral testicle. After discussion of the results, the patient is referred a urologic oncologist with expertise in testicular cancer for further care.
The urologic oncologist orders a computed tomography (CT) abdomen and pelvis with and without contrast, which shows a 1.8-cm pathologic-appearing retroperitoneal lymph node at the level of the left renal vein. Chest radiograph with anteroposterior and lateral views is unremarkable. Tumor markers are as follows: beta human chorionic gonadotropin (beta-HCG) 8 mIU/mL (normal range, 0–4 mIU/mL), alpha-fetoprotein (AFP) 2 ng/mL (normal range, 0–8.5 ng/mL), and lactate dehydrogenase (LDH) 195 U/L (normal range, 119–213 U/L).
What is the approach to the initial workup and diagnosis of testicular cancer?
Clinical Presentation and Physical Exam
The majority of testicular cancers are diagnosed on work-up of a nodule or painless swelling of one testicle, usually noted incidentally by the patient. Approximately 30% to 40% of patients complain of a dull ache or heavy sensation in the lower abdomen, perianal area, or scrotum, while acute pain is the presenting symptom in 10%.3
In approximately 10% of patients, the presenting symptom is a result of distant metastatic involvement, such as cough and dyspnea on exertion (pulmonary or mediastinal metastasis), intractable bone pain (skeletal metastasis), intractable back/flank pain, presence of psoas sign or unexplained lower extremity deep vein thrombosis (bulky retroperitoneal metastasis), or central nervous system symptoms (vertebral, spinal or brain metastasis). Constitutional symptoms (unexplained weight loss, anorexia, fatigue) often accompany these symptoms.3