ADVANCED CARCINOMA OF THE PENIS
Practically all penile cancers are squamous carcinomas. Initially, there is thickening of the glans penis or preputial epithelium, with epithelial pearl formation, central degeneration, and keratinization. Penile cancers may be papillary and exophytic or ﬂat and ulcerative. Cancer cells then penetrate the epithelial basal layers, extend to subcutaneous tissue, and subsequently to lymphatics. If untreated, penile autoamputation can occur.
Penile cancer is rare but deadly, with an estimated 1300 new U.S. cases annually (< 1% of cancers). One reason for the high mortality rate is that patients tend to delay seeking medical attention, with 15% to 50% delaying for more than 1 year from ﬁrst awareness. Risk factors for penile cancer include lack of circumcision, poor penile hygiene, phimosis, age >60 years, multiple sexual partners, and tobacco use. In addition, human papilloma-virus (HPV) infection may increase the risk of penile cancer, because half of all penile cancers are associated with HPV type 16 viral infection. Retained, decom- posing smegma, together with balanoposthitis, may contribute to the initiation of malignancy and explains why adult circumcision does not protect against cancer. Penile cancer usually grows gradually and laterally along the surface of the penis. Buck fascia (see Plate 2-3) acts as a temporary barrier to corporeal invasion. Eventually, the cancer penetrates Buck fascia and the tunica albuginea, after which systemic spread is possible. Penile cancer metastasizes almost solely through the lymphatics, although occasionally hematogenous spread through the dorsal vein of the penis occurs with spread to the axial skeleton. Usually, the tumor metastasizes ﬁrst to superﬁcial inguinal lymph nodes (see Plate 2-9), but the central, presymphyseal lymph node and external iliac nodes may also be involved. Because the lymphatics of the penile shaft intercommunicate, metastases may occur bilaterally despite a unilaterally located primary lesion. The superﬁcial inguinal nodes drain to the deep inguinal nodes beneath the fascia lata. From here, drainage is to the pelvic nodes. Inguinal lymph nodes extensively involved with tumor may erode through the skin and into the femoral artery and vein (see Plate 2-9). While penile cancer can be suspected from its appearance, the diagnosis is established through biopsy of the primary lesion or lymph nodes. Surgical excision constitutes deﬁnitive management of this condition. If the tumor is less than 2 cm in size and conﬁned to the prepuce, circumcision may be sufﬁcient. In small (<1.5 cm) glans lesions, Mohs micrographic surgery or laser ablation may spare the penis and eradicate tumor; however local failure is far more common after organ-sparing procedures. Partial penile shaft amputation is appropriate when the cancer involves the glans and distal shaft. A 2-cm margin is necessary; attempts to limit the resection can result in recurrent tumor. If surgical resection with partial penectomy does not provide an adequate margin, a total penectomy is considered along with a perineal urethrostomy. Following treatment of the primary tumor, management of the inguinal lymph nodes follows. The decision to resect inguinal nodes in patients with no evidence of adenopathy, either clinically or after imaging studies, is controversial. The incidence of occult metastases in patients without palpable adenopathy is 20% to 25%. In addition, radical inguinal lymphadenectomy has a high complication rate (80% to 90%) that includes serous lymphocele formation, wound necrosis and infection, chronic leg edema, phlebitis, and pulmonary embolism.
Therefore, modiﬁcations to this procedure, including limited, superﬁcial lymph node excision and sentinel lymph node biopsy (in which lymphoscintigraphy and intradermal blue dye is injected around the tumor and examined for its presence in the superﬁcial inguinal lymph nodes to determine primary landing sites for cancer), have become popular to reduce the need for, and complications from, radical lymphadenectomy.
The indications for pelvic lymphadenectomy have not been clearly delineated without evidence of enlarged nodes on imaging. When two or more inguinal nodes contain cancer, the probability of pelvic node involvement is high and pelvic lymphadenectomy is indicated. Patients with negative inguinal lymph nodes rarely have pelvic node involvement. Regarding mortality, untreated patients with inguinal metastases rarely survive 2 years. Those with clinically palpable adenopathy and proven metastases have a 20% to 50% survival rate 5 years after deﬁnitive surgical treatment.