The cancer of the penis is a rare neoplasm, and in Western countries are given about 4 cases per 100,000 inhabitants, representing 0.2% of cancers in men and 0.1% of cancer deaths . Its incidence increases with age, with a peak at 60/70 years.
80% of primary tumors are squamous carcinomas (they originate from the epithelium of the skin or mucosa, unlike adenocarcinomas, which originate from the epithelium of the glands) and, although less frequent, there may be metastatic lesions , mainly in the bladder and prostate. They are located in the glans (up to 80%), the foreskin, the balanoprepucial sulcus and the body of the penis. Only 5% is multicenter. Its growth pattern can be in extension (horizontal), in depth (vertical) or “outwards” (verrucous or exophytic).
Left to its natural evolution, penile cancer can end the patient’s life in two years, since the tumor affects the corpora cavernosa and the urethra, and in a next station it metastasizes to locoregional lymph nodes and hematogenously (by blood). it can metastasize to other organs (at a distance).
Penis anatomy
The penis is made up of three cylindrical masses joined by fibrous tissue, two lateral (cavernous bodies) and one inferior (spongy body), where most of the urethra is housed. It is attached to the pubic arch. The overlying skin is loose and is connected to the deepest parts of the organ, at the root, the skin continues with the scrotum and distally (at the tip) folds back on itself forming the foreskin.
The regional lymph nodes are the inguinal (superficial and deep – Rosenmüller or Cloquet -) external and internal iliac, and the pelvic.
Diagnosis of penile cancer and TNM classification
A good medical history and physical examination are essential in diagnosing penile cancer ; Lymph node involvement is the most important prognostic factor and has therapeutic implications.
The biopsy of the lesion serves to determine its nature, and a complete resection is required, with sufficient safety margins.
For the diagnosis of suspicious lymphadenopathy, a fine needle aspiration puncture (FNA) (guided by ultrasound, or not) is usually sufficient, although there are up to 50% of false negatives (that is, it does not diagnose the disease when it does exist). In this case, a lymph node biopsy is necessary . According to some studies, when penile cancer is diagnosed almost half of the cases present palpable inguinal lymphadenopathy, but only half of them are tumorous; that is, the rest are reactive lymphadenopathies: infectious or inflammatory.
Imaging techniques ( CAT and MRI ) are reserved for the study of extension and to locate lesions at a distance; lung, liver and bone are the most frequent locations.
Penile Cancer Classification
The TNM classification is followed by the AJCC ( American Joint Comitee on Cancer ):
T: Primary tumor
| TX | The primary tumor cannot be evaluated. |
| T0 | There is no evidence of primary tumor. |
| Tis | Carcinoma in situ. |
| Ta | Non-invasive warty carcinoma. |
| T1a | The tumor invades the subepithelial connective tissue without lymphatic vascular invasion, and is not poorly differentiated (grade 3). |
| T1b | The tumor invades the subepithelial connective tissue with lymphatic vascular invasion, or is poorly differentiated. |
| T2 | The tumor invades the spongy or cavernous body. |
| T3 | The tumor invades the urethra. |
| T4 | The tumor invades other adjacent structures. |
To this we must add G1, G2 or G3 depending on whether they are well differentiated, moderately differentiated, or undifferentiated, respectively (the degree of differentiation could be explained by how the tumor cells resemble the tissue from which they come). The well-differentiated ones closely resemble the normal tissue cells from which they originate, and are identified with a better prognosis, since they are understood to be less aggressive. Thus, the undifferentiated ones, as they have a rapid growth, have been very different from the normal tissue from which they come (dedifferentiation), so it is understood that they are more aggressive.
