Testicular cancer is cancer that starts in the testicles, the male reproductive organ. The exact cause of testicular cancer is unknown. There is no link between vasectomy and testicular cancer. Factors that may increase a man's risk for testicular cancer include:

      Other possible causes include exposure to certain chemicals and HIV infection. A family history of testicular cancer may also increase the risk. Testicular cancer is the most common cancer in men between the ages of 15 and 35. It can occur in older men, and rarely, younger boys. White men are more likely than African-American and Asian-American men to develop this type of cancer.
    There are two main types of testicular cancer: seminomas and nonseminomas. These cancers grow from germ cells, the cells that make sperm.
        In the United States, between 7,500 and 8,000 diagnoses of testicular cancer are made each year. In the UK, approximately 2,000 men are diagnosed each year. Over his lifetime, a man's risk of testicular cancer is roughly 1 in 250 (0.4%). It is the most common cancer in males aged 20–39 years, the period of peak incidence, and is rarely seen before the age of 15 years.Testicular cancer has one of the highest cure rates of all cancers: in excess of 90 percent; essentially 100 percent if it has not spread (metastasized). Even for the relatively few cases in which malignant cancer has spread widely, modern chemotherapy offers a cure rate of at least 80%.[6] Not all lumps on the testicles are tumors, and not all tumors are malignant; there are many other conditions such as testicular microlithiasis, epididymal cysts, appendix testis (hydatid of Morgagni), and so on which may be painful but are non-cancerous.