The penis consists of three chambers of spongy tissue that contain smooth muscle and many blood vessels and nerves. The corpora cavernosa form two chambers located on both sides of the upper part of the penis. The corpus spongiosum is located below the corpora cavernosa and surrounds the urethra. At the tip of the penis, the corpora cavernosa expands to form the head of the penis, or glans. Each type of penile tissue contains several types of cells, in which different types of penile cancer can form. However, almost all penile cancers start in skin cells of the penis.
Forms of penile cancer
Epidermoid/squamous cell carcinoma accounts for 95 percent of penile cancer. Squamous cell carcinoma can begin anywhere on the penis but it usually develops on or under the foreskin or on the glans. These tumors tend to grow slowly and can usually be cured if found at an early stage. An uncommon form of squamous cell carcinoma, called a verrucous carcinoma or Buschke-Lowenstein tumor, tends to grow very slowly and resembles a large genital wart.
Basal cell carcinoma accounts for less than 2 percent of penile cancers. It is slow-growing and rarely spreads to other parts of the body.
Melanoma is associated with sun exposure but it sometimes occurs on the surface of the penis. This cancer tends to grow and spread quickly.
Sarcoma accounts for only about 1 percent of penile cancers. It develops from blood vessels, smooth muscle, or other connective tissue cells of the penis.
Adenocarcinoma (Paget disease of the penis) is a very rare type of penile cancer that can develop from sweat glands in the skin of the penis.
Risk factors for penile cancer
Human papillomavirus (HPV) infection — The most important risk factor for penile cancer is infection with this virus, which is found in about half of all penile cancers. Skin-to-skin contact, including sexual activity, spreads HPV. The virus can also spread from one body part to another in the same person (for example, from the penis to the anus). HPV infection is common and the body usually clears the infection on its own. However, the infection can become chronic and cause penile cancer. Men who are not circumcised may be more likely to get and stay infected with HPV.
Tobacco use — Men who smoke and/or use other forms of tobacco are more likely to develop penile cancer. Tobacco users who have HPV infections have an even higher risk.
Age — About 80 percent of US men with penile cancer are at least 55 when diagnosed, with 68 being the average age of diagnosis. However, 60 is the average age of diagnosis for African American and Hispanic men
Smegma — This thick substance caused by dead skin cells, bacteria, and oily skin secretions can build up under the foreskin. It can irritate and inflame the penis, increasing cancer risk, and might also make it harder to see very early cancers. Uncircumcised men should pull back, or retract, the foreskin and thoroughly wash the penis on a regular basis.
Phimosis — Penile cancer is more common in men with phimosis, which occurs when the foreskin becomes tight and is difficult to retract. Men with phimosis are less likely to be able to thoroughly clean the penis, leading to the buildup of smegma and to inflammation.
HIV/AIDS — Men with HIV/AIDS have a higher risk of penile cancer. This higher risk may be linked to a weakened immune system resulting from AIDS, but additional factors might also play a role. For example, men with HIV are more likely to smoke and be infected with HPV.
Psoriasis treatment — Men who have received the drug psoralen combined with ultraviolet light have a higher risk of developing penile cancer. To help lower their risk, men receiving this therapy (called PUVA) now have their genitals covered during treatment.
Symptoms of penile cancer
A growth or sore on the penis, especially on the glans or foreskin, but cancer also occurs on the shaft.
Changes in penis color
Thickening of penis skin
Persistent discharge, with a foul odor beneath the foreskin
Blood coming from the penis tip or from under the foreskin
Unexplained pain in the penis shaft or tip
Irregular or growing bluish-brown flat lesions or marks beneath the foreskin or on the penis
Reddish, velvety rash beneath the foreskin
Small, crusty bumps beneath the foreskin
Swollen lymph nodes in the groin
Irregular swelling at the end of the penis
How is penile cancer treated with radiation?
External-beam radiation therapy (EBRT) is delivered from outside the body. A wax or plastic block or mold may be used to hold the penis in the exact same position for each treatment. Shields may be used to protect the groin and testicles.
Brachytherapy places a radioactive source into or next to the penile tumor and may be delivered in two ways. Interstitial radiation delivers radioactive pellets through needles inserted into the penis. Needle insertion occurs in the operating room and the needles are kept in for several days. A second method, plesiobrachytherapy, is used for tumors near the surface of the penis. In this method (which is not often used in the US), radioactive material is placed in a cylinder or a mold surrounding the penis. As part of brachytherapy treatment, a soft tube, called a Foley catheter, is put through the penis and into the bladder to drain out urine during the procedure.
Radiation may be used to treat some smaller penile cancers instead of surgery.
Radiation may be used when surgery is not an option.
Radiation may be used before surgery (along with chemo) to help shrink the tumor and make it easier to remove with less damage to the penis.
Radiation may be used after surgery to remove lymph nodes, to try to reduce the risk of cancer returning.
Radiation may be used for advanced cancer, to try to slow cancer growth or to relieve symptoms (palliative treatment).
More extensive information about penile and other cancers may be found at these sites:
American Cancer Society: Cancer.org
American Society of Clinical Oncology: Cancer.net
National Cancer Institute: Cancer.gov