What Are Testicles?
Testicles, also termed testes or testis, form a part of the male reproductive system. The testicle is smaller than a golf ball size in adult males. A sac of skin called the scrotum holds the testicles under the base of the penis.
What Are the Functions of the Testicles?
Testicles produce male hormones called androgens, like testosterone. Testicles also produce sperm, the cells required for the fertilization of a female egg. Testicles have long, slender tubes; these tubes are called seminiferous tubules. Sperms are made in these tubes. Sperms are stored in a small coiled tube called the epididymis. Ejaculation occurs when the sperm cells are carried from the epididymis to the seminal vesicles. Sperms then mix with the fluids made by the vesicles and the prostate gland to form semen. This fluid enters the urethra, located in the center of the penis. The urethra helps in the excretion of urine as well as sperm.
What Are the Types of Testicular Cancer?
The testicles are made up of different cells; each cell can give rise to a different type of cancer.
Germ Cell Tumors:
Germ cells give rise to the maximum of cancers in the testicles. Germ cells are the cells that make sperm. The germ cell tumor in the testicles is of the following two types. Seminomas and non seminomas are found in equal proportions. Some testicular cancers have both seminoma and nonseminoma cells. The mixed germ cell tumors are called non seminomas as they grow and spread like nonseminoma variants.
Seminomas:
Seminomas grow and spread slowly as compared to non seminomas. The sub-classification of these tumors is as follows.
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Classical or Typical Seminomas.
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Spermatocytic Seminomas.
Classical Seminoma:
Most of the seminomas are classical in nature. Classical seminomas are seen in men in the age group of 25 and 45 years.
Spermatocytic Seminoma:
Spermatocytic seminoma is a rare type of seminoma seen in older men aged about 65 years. Spermatocytic tumors grow slowly and do not spread to other body parts. Some seminomas tend to increase blood protein levels called human chorionic gonadotropin (HCG). HCG can be detected in simple blood tests. HCG is a tumor marker for a few testicular cancers. It is used to diagnose and check the patient's response to the treatment.
Non seminomas:
Non seminomas are germ cell tumors in men in their late teens or early thirties. These tumors are a combination of different types of cells, but the treatment remains the same. The four types of nonseminoma tumors are as follows.
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Embryonal carcinoma.
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Yolk sac carcinoma.
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Choriocarcinoma.
Embryonal Carcinoma:
Embryonal cells are found in around 40 % of testicular tumors. However, true and only embryonal carcinomas occur in only 3 % to 4 % of cases. Under a microscope, these tumors are visualized as tissues of early embryos. Such nonseminoma grows rapidly and spreads around the testicle. Embryonal carcinoma increases blood levels of a tumor marker protein, alpha -fetoprotein (AFP), and human chorionic gonadotropin (HCG).
Yolk Sac Carcinoma:
Yolk sac carcinomas are tumors in which the cells look like the yolk sac of an early human embryo. Yolk sac carcinoma is also called yolk sac tumor, endodermal sinus tumor, infantile embryonal carcinoma, orchido blastoma. Yolk sac carcinoma is a common cancer seen in children. Pure yolk sac carcinomas are not seen in adults. Children show successful treatment for these cancers. Yolk sac carcinomas show a good response to chemotherapy and show increased blood levels of AFP (alpha fetoprotein).
Choriocarcinoma:
Choriocarcinoma is a rare and fast-growing testicular cancer seen in adults. The pure type of choriocarcinoma spreads to other body parts, like the lungs, bones, and brain. Choriocarcinoma cells are also found along with nonseminoma cells in a mixed germ cell tumor. Choriocarcinoma increases blood levels of HCG (human chorionic gonadotropin).
Teratoma:
Teratomas are germ cell tumors under the microscope as layers of a developing embryo, the endoderm, mesoderm, and ectoderm. Pure teratomas are rarely seen and do not increase alpha-feto protein or human chorionic gonadotropin levels in the blood.
There are three main types of teratomas:
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Mature Teratomas are tumors formed by adult tissue cells. They do not spread. They can be treated with surgery. There is a risk of recurrence.
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Immature Teratomas are poorly developed cancers. They have cells resembling an early embryo. Immature teratomas invade the surrounding tissues, metastasize around the testicle, and recur after treatment.
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Somatic Teratomas are rare. They resemble mature teratomas but also have areas that normally develop around the testicle.
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Carcinoma In Situ of the testicle is a non-invasive disease or intratubular germ cell cancer. The cells appear abnormal microscopically but do not escape from the seminiferous tubules. Carcinoma in situ is not always invasive in nature. It is difficult to find carcinoma in situ before it invades as it does not show any symptoms. The diagnosis is made through a biopsy or is found incidentally when a testicular biopsy is done to evaluate infertility. Invasive cancer cells, along with the seminiferous tubules, grow into the surrounding structures of the testicle. These cancer cells spread to the lymph nodes through lymphatic vessels or the blood to other body parts.
Stromal Tumors:
Tumors are seen in hormone-producing tissues. They are also called gonadal stromal tumors. The main types of stromal tumors are Leydig cell tumors and Sertoli cell tumors.
Leydig Cell Tumors:
Leydig cell tumors start in the Leydig cells of the testicle, which produces the male sex hormone testosterone. Leydig cell tumors are found in adults as well as children. These tumors sometimes produce estrogen, female sex hormones, and testosterone. Leydig cell tumors are not cancerous. They do not respond to chemo or radiation therapy.
Sertoli cell tumors:
Sertoli cell tumors start in normal Sertoli cells. Sertoli cells support and provide nutrients to the germ cells. These tumors are also benign.
Secondary Testicular Cancers:
Secondary testicular cancers originate in one organ and metastasize to the testicle. They are not true testicular cancers.
Lymphoma:
Lymphoma is the commonest secondary testicular cancer. Testicular lymphoma is seen in men older than 50 years. The treatment for lymphoma is surgical excision, followed by radiation or chemotherapy.
Conclusion:
Testicular cancer is the most common malignancy in men between 15 to 45 years. The cause of testicular cancer is multifactorial, involving genetic and environmental agents. With recent advances in research, epidemiology, pathophysiology, diagnosis, and management options are available. The success rates are as high as 90 %. Also, testicular cancer is one of the treatable malignancies.
