Penile Cancer is a Rare
June 6th, 2008 by admin
Cancer that is easily misdiagnosed. Learning about the disease is, therefore, especially important for men.
Answering questions about penile cancer is Curtis A. Pettaway M.D., associate professor in M. D. Anderson’s Department of Urology.
What is penile cancer?
Penile cancer is a malignant growth starting in the epithelium (surface) of the glans penis (head of the penis) or the shaft. It is very rare, affecting less than one in 100,000 males.
Squamous cell carcinoma represents the most common type of penile cancer and accounts for about 95% of cases.
Other types of penile malignancy include:
— Sarcoma
— Melanoma
— Lymphoma
— Leukemia
Occasionally the penis also will be a site where cancer spreads from primary sites such as the bladder, prostate and rectum.
How many cases of penile cancer are treated at M. D. Anderson each year?
Approximately 30 patients with penile cancer are seen yearly at M. D. Anderson. Although this seems like a relatively small number of cases, the average urologist will see about one case every five years. For these reasons it is difficult to perform large clinical trials to determine the best ways to treat the disease or evaluate new therapies.
The incidence rates in certain countries such as
What are the causes, risk factors and preventive measures?
Most penile cancers are diagnosed in men between the ages of 50 to 70 years of age. However, about 30% of cases occur in men who are 50 years of age or less.
Risk factors include:
— Lack of neonatal circumcision
— Phimosis (difficulty retracting foreskin)
— Human papilloma virus infection
— Tobacco products
Among groups that practice neonatal circumcision, the rates of penile cancer are rare. The foreskin is believed to harbor bacteria, body oils and debris (collectively called smegma) that if not properly cleaned, can lead to repeated episodes of inflammation, which leads to scarring of the foreskin and phimosis. Foreskins removed due to phimosis often have atypical cells noted by the pathologist.
Other modifiable risk factors also can contribute to the development of penile cancer in men with a foreskin.
Human papilloma virus infection is a known cause of cervical cancer. Virus types 16 and 18 are the predominant types implicated in penile cancer. As HPV is a sexually transmitted phenomenon, a significant portion of both penile and cervical cancers could be prevented. Of importance: not all types of HPV infection can cause cancer. Specifically, types 6 and 11 - while associated with the presence of viral warts - have not been associated with cancer.
Tobacco products are known carcinogens implicated in lung, bladder, head and neck and renal cancers and also are implicated in penile cancer. The risk of penile cancer is increased in men who smoke or chew tobacco products, even when considering those who are circumcised.
How is penile cancer treated?
Natural history
Carcinoma of the penis usually begins with a small lesion, which gradually extends to involve the entire glans and then the penile shaft. The most common site of spread is to the inguinal lymph nodes. If untreated, the inguinal metastases enlarge, ulcerate through the skin (causing infection) or grow into the adjacent femoral vessels producing hemorrhage (and potentially death).
The goals of treatment are to control the primary tumor and to diagnose and treat inguinal metastases at the earliest possible time point.
Primary tumor
Treatment to control the primary tumor includes:
— Partial or total penile amputation
— Limited excisions
— Radiation therapy
— Laser ablation
Chemotherapy has been reported to treat the primary tumor with only limited success.
The most effective therapy to treat the primary tumor is partial or total amputation. Success rates vary from 92% to 100% in preventing local recurrence. However, sexual quality of life is naturally decreased in men treated with amputation.
Recent data suggests that in select patients with low-grade/low-stage tumors, penile preservation is feasible with low to moderate tumor recurrence rates (8% to 33%). This does not appear to compromise survival in patients who are followed closely. Overall, for men with a treated primary tumor who are at low risk of the cancer spreading, the five-year, disease-free survival rate is approximately 90%.
At M. D. Anderson penile preserving strategies are available for appropriate candidates.
How is penile cancer that has spread treated?
The extent of regional lymph node metastasis dictates survival in penile cancer. Good prognostic factors in patients undergoing surgery whose penile cancer has spread to the groin include:
— A maximum of one to two nodes located on only one side of the groin area, versus both sides
— No extranodal extension - invasion of cancer through the lymph node into the surrounding tissue
— No spread to the pelvic lymph nodes
Current strategies are aimed at defining the presence of microscopic disease in the nodes so that surgery can be performed earlier with a higher curative potential. Unfortunately, even if the physical examination is negative for nodal enlargement, metastases are present in about 25% of patients. Because inguinal surgery can be associated with complications, it is prudent to try to define which patients are at highest risk.
Recently, we developed prognostic categories to define which patients without lymph node enlargement on physical examination might still have microscopic disease in the inguinal (groin) lymph nodes.
Patients in the low-risk group are observed. Those in the high-risk group undergo modified groin dissections or lymph node mapping to try and define where in the surgical field the cancer has spread. In this manner we can limit the morbidity of the procedure for our patients, while aggressively treating those who actually have metastasis.
Overall, for patients with limited inguinal disease the five-year, disease-free survival rate is between 60% and 80%. For those patients with poor prognostic factors, the five-year survival rate is 0% to 10%. In this latter group, we are pioneering the use of chemotherapy prior to surgical resection to potentially improve outcomes. Preliminary results are encouraging in those patients who respond to chemotherapy.
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