Penis cancer is thankfully rare, but cases are rising. Some experts predict a 77% increase in penis cancer by 2050.
While developing countries tend to have the highest rates of penis cancer, cases are increasing in most European countries. As populations age, cases tend to go up. Being over 50 is one of the main risk factors for penis cancer, and Europe has an ageing population.
Other risk factors include a narrowed foreskin, poor genital hygiene and smoking tobacco. Penis cancer is rare in those who have been circumcised at birth.
Squamous cells in the skin of the penis are responsible for over 90% of penis cancers. Other malignancies, such as melanoma, basal cell carcinoma or sarcoma are less frequent. Infection with human papillomaviruses (HPV) has been identified in about half of squamous cell cancer cases.
Papillomaviruses spread through skin contact and are probably humankind's most commonly transmitted sexual infection. Over 70% of sexually active adults will contract papillomavirus infections, usually in adolescence.
Infections usually don't cause symptoms and can disappear over months to a few years without long-term complications. Previous infection with HPV, unfortunately, does not appear to protect against future infection.
These infections can persist just below the skin surface. In the penis, this can result in changes to the skin texture and colour – known as "pre-malignant changes". A painless, symptomless ulcer or wart may develop, commonly on the glans and under the foreskin.
HPV 16, the most common high-risk type of HPV, can trigger malignant changes in tissues of the penis or the cervix, mouth, throat, vulva, vagina and anus. It is probably the most carcinogenic HPV. Fortunately, HPV vaccines have already done a great job at reducing the rates of cancer of the cervix.
Effects of these jabs on penis cancer are likely to take longer to emerge because there is usually a long period between HPV infection and cancer emerging.
Diagnosing penis cancer is often delayed because patients experience guilt or embarrassment. Many men report self-medicating with antimicrobial or steroid creams while putting off an appointment with a doctor.
Doctors often contribute to delays, too, as lesions are sometimes wrongly classified as benign. If malignant cells have spread to the groin lymph glands, the chance of a cure is much lower, so speedy diagnosis and treatment are important.
Treatment
Cancerous tissue can be successfully removed with laser or micro-surgery. This might be combined with chemotherapy or radiotherapy. However, some tumours will not respond well to treatment and the penis may need to be amputated. But this is always a last resort.
A recent BBC report revealed that Brazil has one of the highest rates of penis amputation, with nearly two carried out each day.
But there is hope on the horizon. New approaches, such as the use of engineered T cells (a type of immune cell) that attack HPV-infected cells, or immunotherapies such as tislelizumab that improve immune responses to squamous cell tumours, have proved effective in a few cases.
Colin Michie, Deputy Lead, School of Medicine, University of Central Lancashire
This article is republished from The Conversation under a Creative Commons license. Read the original article.