What is Penile Cancer?
Penile carcinoma (cancer) is the cancer of the penis which is not very common. It derives from the epithelium of the inner prepuce and glans which turn cancerous and form squamous cell carcinoma of the penis.
Penile cancer is a rare cancer and the incidence in European and United States is about 1 in 100,000 male. Penile carcinoma accounts for 20-30% of all cancers diagnosed in men who live in Asia, Africa, and South America.
It often is diagnosed in patients above 60 years old and peaks in males above 80 years old.
What causes Penile Carcinoma?
There are several risk factors that may be associated with penile cancer. They include:
1.HPV infection especially subtype 16 & 18
2. Hygienic practices and cultural and religious beliefs: Circumcision (removing part of the foreskin) during neonatal period is protective against penile cancer. Circumcision during adulthood is non- protective.
3.Phimosis (a condition in which the foreskin of the penis cannot be pulled back over the glans). About 25-75% of patients with penile cancer have phimosis.
4.Multiple sexual partners: increases chance of getting sexually transmitted diseases especially HPV infection.
5.Smoking and chewing tobacco increases the risk of penile cancer
6.Chronic inflammatory conditions/trauma of the penis: balanoposthitis,lichen sclerosus, and atrophicus (balanitis Xerotica obliterans) may result in cell changes of the penis and increases risk of cancerous change.
Clinical presentation of penile cancer
Penile cancer usually begin as small lesions which can range from irregular white grey flat lesion that fail to heal, eroded ulcer with rolled up edges to reddish ulcerative mass. They will grow gradually and then spread to the entire glans penis, prepuce and invade into the corpora and the penis shaft. The cancerous cells then will spread to the lymph nodes in the groin area and further spread to distant organs in very advance stage. If left untreated sometimes the penis may have auto-amputation.
Benign penile lesions include pearly penile papules/papillomas (small lumps) that occur commonly on the glans penis of uncircumcised males. These are non-cancerous and does not require treatment.
Pre-malignant lesions are pre-cancerous lesions which include balanitis xerotica obliterans, leukoplakia and genital warts. Balanitis Xerotica Obliterans is a variation of lichen sclerosus et atrophicus which appears as a white patch on the prepuce or glans and often involves the urethral meatus and can cause urethral obstruction.
Leukoplakia will appear as solitary plaque (Flat patch) or multiple whitish plaques, which often involve the meatus. It is associated with squamous cell carcinoma.
Genital warts are associated with Human Papilloma Virus infection. HPV subtypes 16, 18, 31, 33, 35, and 39 are associated with cancerous changes.
Malignant (cancer) lesions are squamous cell carcinoma. Bowen diseaseis a subset of squamous cell carcinoma commonly appear in the genitalia area.
Your clinician will take a clinical medical history from you. Then your physician will carry out a physical examination of your penis, genitalia and groin area.
The size, location, number, color, morphology and appearance of the penis lesion will be recorded. The groin lymph nodes will also be examined as it is the first place the cancerous cells will spread to.
Diagnostic tests of Penile Cancer
There are no cancer markers that can be tested for penile cancer. The suspicious penile lesion will be biopsied and the tissue cells are sent to the laboratory to confirm presence of any cancerous cells. If there is any enlarged lymph node, biopsy of the lymph node is also warranted to see if cancer has spread to the lymphatic system.
Imaging studies like MRI and Ultrasound are good modalities to assess the extent of invasion of local cancer and the lymph nodes. Other imaging study like PET and CT scan can also be used for staging of the penile cancer. Rarely Chest X-ray can help detect any metastases (spread of cancer to distant organs).
Stages of Penile Cancer
Penile cancer is classified into stages according to the Tumor Nodal Metastases (TNM) system depending on how far the cancer has invaded into the tissue, whether it has spread to the lymph nodes and other distant organs.
Treatment of Penile Cancer
Treatment modalities depend on the stage of the penile cancer, the location and size of the tumor and patient’s fitness for operation. The treatment modalities available include topical treatment, surgery (main treatment), radiation therapy and chemotherapy.
For intra-epithelial cancers like Bowen disease or erythroplasia of Queyrat which had not invaded the basement membrane can be treated with topical 5-fluorouracil which causes denudation of the cancer cells.
Surgery is the mainstay treatment for all stages of penile cancer.
1.Mohs surgery: The cancer is removed layer by layer and each layer is examined under microscope for cancerous cells. The layers are removed till normal cells are seen.
2.Circumcision: For small penile cancer limited to the prepuce then circumcision may be sufficient enough.
3.Cryosurgery: Using extreme cold to freeze and destroy the abnormal tissue.
4.Laser surgery: uses external laser beam as knife to cut through and remove the cancer. The types of laser used include carbon dioxide, Nd: YAG, argon, and potassium-titanyl-phosphate (KTP) lasers.
5.Wide local excision with lymphadenectomy: The cancer is removed surgically with a margin of normal healthy tissues. Lymph nodes that are involved are also surgically removed at the same time.
6.Partial or total penectomy: Partial or total amputation of the penis are reserved for patients with more extensive disease. Reconstruction surgery post-amputation can restore cosmetic effect of the remnant penis.
After surgery, your physician may advise adjuvant chemotherapy and/or radiotherapy to kill any possible remnant cancer cells.
Radiotherapy uses high energy x-ray beams to kill and stop the cancer cells growth. It is usually a add on therapy for patients post-surgery and to relieve pain in patients who has cancer spread to the bones.
Candidates for radiation therapy alone include young men with small < 3 cm superficial, exophytic lesions or noninvasive cancers on the glans or coronal sulcus.
In patients who are reluctant for penis amputation surgery, they may opt for radiotherapy. However squamous cell carcinoma is quite resistant to radiation therapy. High doses may need to be used and have side effects like urethral fistulae, strictures (narrowing), penile necrosis (cell death), pain, and edema.
External Beam radiation therapy involves repeated external beam radiation on entire shaft of penis. Each session takes 10-15 minutes and will be done 4-5 times weekly for 4-6 weeks. Brachytherapy involves wearing a radioactive mold over the penis for 12 hours daily and for 7 days.
Chemotherapy uses anti-cancer drugs like cisplatin, bleomycin, methotrexate, and fluorouracil to kill cancer cells and stop them from dividing. Chemotherapy can be given by injecting the drugs into the blood system or by ingesting chemotherapy pills.
Chemotherapy can be used as an adjuvant therapy for patients post-surgery. It can also be used for patients who has advance cancer that has spread to the lymph nodes and other organs.
As the chemotherapy drugs are toxic, they not only kill cancer cells they also kill healthy cells, it has a number of side effects. Side effects include gastrointestinal upset, diarrhea, vomiting, hair fall and bone marrow suppression.
As the cancer can recur even after surgery and chemoradiation therapy, follow up with your surgeon is important. At each follow up, your surgeon will conduct a clinical examination to rule out any recurrence. Imaging studies may be ordered to rule out any recurrences in lymph nodes and distant organs.