Penile Cancer is a malignant growth found on the skin or in the tissues of the penis. Around 95% of penile cancers are squamous cell carcinomas. Other types of penile cancer such as Merkel cell carcinoma, small cell carcinoma, melanoma and other are generally rare.
Signs and symptoms
- Redness of the penis
- Rash on the penis
- Foul smelling discharge from the penis
- Pain in the penis
- Growth or sore on the penis that doesn’t heal within four weeks (may look like a wart, ulcer, or blister), may or may not be painful
- Bleeding from the penis or from under the foreskin
- Change in color of the penis
HIV infection—HIV-positive men have eight-fold increased risk of developing penile cancer than HIV-negative men.
Human papillomavirus—HPV is a risk factor in the development of penile cancer. According to the Center for Disease Control and Prevention (CDC), HPV is responsible for about 800 (about 40%) of 1,570 cases of penile cancer diagnosed annually in the United States. There are more than 120 types of HPV.
Genital warts—Genital or perianal warts increase the risk of invasive penile cancer by about 3.7 times if they occurred more than two years before the reference date. About half of men with penile cancer also have genital warts, which are caused by HPV.
Hygiene and injury
Poor hygiene—Poor hygiene can increase a man’s risk of penile cancer.
Smegma—Smegma, a whitish substance that can accumulate beneath the foreskin, is associated with greater risk of penile cancer.
The American Cancer Society suggests that smegma may not be carcinogenic, but may increase the risk by causing irritation and inflammation of the penis.
Balanitis and penile injury—Inflammation of the foreskin and/or the glans penis (balanitis) is associated with about 3.1 times increased risk of penile cancer.
It is usually caused by poor hygiene, allergic reactions to certain soaps, or an underlying health condition such as reactive arthritis, infection, or diabetes. Small tears and abrasions of the penis are associated with about 3.9 times increased risk of cancer.
Phimosis—Phimosis is a medical condition where the foreskin cannot be fully retracted over the glans. It is considered a significant risk factor in the development of penile cancer (odds ratio of 38–65). Phimosis may also be a symptom of penile cancer.
Paraphimosis—Paraphimosis is a medical condition where the foreskin becomes trapped behind the glans. It is considered a risk factor for the development of penile cancer.
Circumcision—Some studies show that circumcision during infancy or in childhood may provide partial protection against penile cancer, but this is not the case when performed in adulthood.
It has been suggested that the reduction in risk may be due to reduced risk of phimosis; other possible mechanisms include reduction in risk of smegma and HPV infection.
Penile cancer is rarely seen in men under the age of 50. About 4 out of 5 men diagnosed with penile cancer are over the age of 55.
Lichen sclerosus is a disease causing white patches on the skin. Lichen sclerosus increases the risk of penile cancer.
As the exact cause of lichen sclerosus is unknown, there is no known way to prevent it.
Chewing or smoking tobacco increases the risk of penile cancer by 1.5–6 times depending on the duration smoking and daily number of cigarettes.
Men with psoriasis who have been treated using UV light and a drug known as psoralen have an increased risk of penile cancer.
Penile cancer arises from precursor lesions, which generally progress from low-grade to high-grade lesions. For HPV related penile cancers this sequence is as follows:
- Squamous hyperplasia;
- Low-grade penile intraepithelial neoplasia (PIN);
- High-grade PIN (carcinoma in situ—Bowen’s disease, Erythroplasia of Queyrat and bowenoid papulosis (BP));
- Invasive carcinoma of the penis.
However, in some cases non-dysplastic or mildly dysplastic lesions may progress directly into cancer. Examples include flat penile lesions (FPL) and condylomata acuminata.
In HPV negative cancers the most common precursor lesion is lichen sclerosus (LS).
Around 95% of penile cancers are squamous cell carcinomas. They are classified into the following types
- basaloid (4%)
- warty (6%)
- mixed warty-basaloid (17%)
- verrucous (8%)
- papillary (7%)
- other SCC mixed (7%)
- sarcomatoid carcinomas (1%)
- not otherwise specified (49%)
Other types of carcinomas are rare and may include small cell, Merkel cell, clear cell, sebaceous cell or basal cell tumors. Non-epithelial malignancies such as melanomas and sarcomas are even more rare.
Like many malignancies, penile cancer can spread to other parts of the body. It is usually a primary malignancy, the initial place from which a cancer spreads in the body. Much less often it is a secondary malignancy, one in which the cancer has spread to the penis from elsewhere.
The staging of penile cancer is determined by the extent of tumor invasion, nodal metastasis, and distant metastasis.