Recent advances in imaging studies for staging of penile and urethral carcinoma

Over the past decade, the principal advances in the imaging of genitourinary cancer have come in the fields of ultrasound, CT, and MR imaging. As applied to carcinomas of the urethra and penis, these techniques show promise. The local staging of the lesion may be done with either ultrasound or MR imaging. Ultrasound has correctly staged two penile cancers and predicted the presence or absence of lymph node metastasis. Sonourethrography has been successful in the evaluation of urethral stricture disease and should now be studied for imaging carcinomas of the urethra. Magnetic resonance imaging allows direct tumor visualization. This and its large field of view make it more accurate than clinical staging by palpation. In addition, MR imaging can identify destruction of both the tunica albuginea and the septum between the corpora by metastases to the penis or contiguous involvement by other neoplasms. It also offers the advantage of imaging in three orthogonal planes, giving more anatomic detail of the primary tumor. Tissue contrast is superb, and the study can simultaneously evaluate the pelvic nodes. After careful palpation of the primary tumor and examination of the regional and distant lymph nodes, we perform physical examination under anesthesia and obtain histologic confirmation of the cancer. We then base our decision to obtain further imaging studies on the grade and invasiveness of the tumor along with the findings on physical examination. In patients with tumors that appear to be superficial and are of low grade who have no evidence of regional or distant nodal disease on physical examination, further imaging is not carried out. In addition, tumors that appear to be limited to the glans or distal penile shaft do not require additional imaging, as palpation is usually sufficient. For those patients with tumors that are of high grade or show evidence of local invasion or who have clinical evidence of regional or distant metastases, additional imaging with pelvic MR or CT, chest radiographs, and bone scan is carried out. Tumors originating in the bulb of the penis also require additional imaging because palpation is inadequate for the determination of local invasion. We do not routinely use lymphangiography, cavernosography, or fine-needle aspiration biopsy, although these techniques may be helpful in individual cases.