Incidence and Mortality

It is estimated that 8,090 new cases of testicular cancer will be diagnosed in men, and 380 men will die of this disease in the United States in 2008.[1] Testicular cancer is the most common malignancy in men aged 15 to 35 years. It accounts for approximately 1% of all cancers in men. Worldwide, testicular cancer has more than doubled in the last 40 years. Incidence varies considerably in different geographical areas, being highest in Scandinavia and Switzerland; intermediate in the United States, Australia, and the United Kingdom; and lowest in Asia and Africa. It also varies according to ethnic groups, with a much higher rate among whites than blacks in the American population.[2] An annual increase of 3% is reported for Caucasian populations.[3] Despite the increase in observed incidence, there has been a dramatic decrease in mortality as a result of effective treatments.

Germ cell tumors (GCT) of the testis constitute 94% of testicular tumors and include five basic cell types: seminoma, embryonal carcinoma, yolk sac tumor, teratoma, and choriocarcinoma. Sixty percent of GCT are seminomas; the remainder are nonseminomatous germ cell tumors. Almost half of all germ cell tumors contain more than one of the five cell types.

Three subtypes of pure seminomas have been described: classic, anaplastic, and spermatocytic. Classic seminoma accounts for 80% to 85% of all seminomas and occurs most commonly in men aged 30 to 50 years. Anaplastic seminoma accounts for 5% to 10% of all seminomas and has an age distribution similar to that of the typical subtype. A number of features suggest that anaplastic seminoma is a more aggressive and potentially more lethal variant of typical seminoma. These characteristics include greater mitotic activity, higher rate of local invasion, increased rate of metastatic spread, and higher rate of tumor marker (human chorionic gonadotropin beta, or beta hCG) production. Spermatocytic seminoma accounts for 2% to 12% of all seminomas, and nearly half occur in men older than 50 years. The cells closely resemble different phases of maturing spermatogonia. The metastatic potential of this tumor is extremely low, and the prognosis is favorable.[4]

Risk Factors

Unlike most other cancers, testicular cancer is generally found in young men.[5] In white men, testicular cancer is the most common cancer from age 20 years to age 34 years, the second most common from age 35 years to age 39 years, and the third most common from age 15 years to age 19 years. This type of cancer is 4.5 times more common among white men than black men,[6] with intermediate incidence rates for Hispanics, American Indians, and Asians. High-risk groups exist. Males with cryptorchidism have 3 to 17 times the average risk. Approximately 7% to 10% of patients with testicular tumors have a history of cryptorchidism.[4,7] Orchiopexy may not prevent cancer in these children but allows clinical surveillance of patients with a previously impalpable gonad. There is also an increased risk in males with gonadal dysgenesis and Klinefelter syndrome.[8] Men with a family history of testicular cancer may be at a higher risk of this disease.[9] A history of testicular cancer is associated with a higher risk of a contralateral tumor.[4,7]