Penile Cancer

Penile cancer, also known as penile carcinoma, is a malignancy that develops in the skin or tissues of the penis. This rare form of cancer had an incidence of 36,068 cases globally in 2020, resulting in 13,211 deaths.

Signs and Symptoms

Penile cancer manifests through various symptoms including redness, irritation, skin thickening on the glans or inner foreskin, and ulcerative or outward-growing lesions. Patients may also experience penile discharge, dysuria (burning or tingling while urinating), and bleeding from the penis.

Risk Factors

Several risk factors are associated with penile cancer, including infections, hygiene practices, and other health conditions.

Infections

Human papillomavirus (HPV) and HIV infections significantly increase the risk of developing penile cancer. HPV is responsible for approximately 40% of penile cancer cases in the United States, with more than 120 types identified. Genital warts caused by HPV also elevate the risk.

Hygiene and Injury

Poor hygiene, smegma accumulation, and conditions like balanitis and phimosis are linked to higher incidences of penile cancer. Phimosis, where the foreskin cannot be retracted, is a significant risk factor. Circumcision in infancy or childhood may offer partial protection by reducing the risk of phimosis and HPV infection.

Other Risk Factors

Age is a notable factor, with most cases occurring in men over 55. Conditions like lichen sclerosus, tobacco use, and ultraviolet light exposure (particularly in psoriasis treatment) also elevate risks.

Pathogenesis

Penile cancer arises from precursor lesions that typically progress from low-grade to high-grade. This progression is more pronounced in HPV-related cancers, advancing from squamous hyperplasia to invasive carcinoma. In HPV-negative cancers, lichen sclerosus is the common precursor lesion.

Diagnosis

The International Society of Urological Pathology (ISUP) recommends using p16INK4A immunostaining for diagnosing and classifying HPV-related penile cancer.

Classification and Staging

Approximately 95% of penile cancers are squamous-cell carcinomas, which are further categorised into types like basaloid, warty, mixed warty-basaloid, verrucous, and papillary. The staging follows the AJCC TNM guidelines, ranging from TX (tumour cannot be assessed) to T4 (tumour invades adjacent structures). Prognostic groups range from Stage 0 (carcinoma in situ) to Stage IV (invasion into adjacent structures or distant metastasis).

HPV Positive Tumours

HPV is prevalent in about 40% of penile cancers, with HPV16 being the predominant genotype. Warty/basaloid cancers have a higher HPV prevalence (70–100%) compared to other types.

Prevention

Preventive measures include HPV vaccination, condom use, good genital hygiene, smoking cessation, and circumcision during infancy or childhood. Practising proper hygiene and avoiding prolonged retraction of the foreskin can prevent phimosis and paraphimosis, respectively.

Treatment

Treatment varies by tumour stage and includes surgery, radiation therapy, chemotherapy, and biological therapy. Surgical options include wide local excision, microsurgery, laser surgery, circumcision, and penectomy. Radiation therapy is used for organ-sparing in early-stage cancer and adjuvant therapy for advanced disease.

Prognosis

The prognosis depends on the cancer stage at diagnosis, with early detection leading to better outcomes. The overall 5-year survival rate for penile cancer is approximately 50%.

Epidemiology

Penile cancer is rare in developed nations, with an incidence ranging from 0.3 to 1 per 100,000 annually. It accounts for 0.4–0.6% of all malignancies. In developing countries, the incidence is higher, constituting up to 10% of malignant diseases in men.

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Self-assessment MCQs (single best answer)

Which virus is responsible for approximately 40% of penile cancer cases in the United States?

What is the most common type of penile cancer?

Which risk factor is significantly reduced by circumcision in infancy or childhood?

What is the 5-year survival rate for penile cancer?

Which staging classification system is used for penile cancer?

Which diagnostic method is recommended by the International Society of Urological Pathology (ISUP) for HPV-related penile cancer?

Which HPV genotype is most commonly associated with penile cancer?

Which of the following is NOT a preventive measure for penile cancer?

What percentage of penile cancers are squamous-cell carcinomas?

What is a common precursor lesion in HPV-negative penile cancers?