Sentinel node biopsy in squamous-cell carcinoma of the anal canal

Radiochemotherapy is the standard treatment for patients with carcinoma of the anal canal. Therefore, a surgical specimen is not usually obtained. Inguinal lymph node metastases cannot be accurately predicted by either clinical examination or imaging techniques. In this study, we applied the sentinel node technique in patients with anal canal squamous-cell carcinoma to determine whether this provided more reliable staging of tumors.

From May 2007 to May 2009, we enrolled 11 patients (7 women) with a mean age 65 (range 39-80) years with squamous-cell carcinoma of the anal canal and clinically and radiologically negative groin lymph nodes. The patients were staged with endorectal ultrasound, computed tomographic scan, magnetic resonance imaging of the pelvis, and positron emission tomography. There were two T1, four T2, and five T3 tumors (International Union Against Cancer classification). Lymphoscintigraphy with peritumoral 99mTc colloid injection was performed 16 to 18 h before surgery. During the surgery, patent blue dye was injected peritumorally, and the sentinel inguinal node was identified by a handheld gamma probe and dye visualization.

The sentinel lymph node was detected in all 11 patients by scintigraphy; in 9 cases, the lymph node was in the inguinal region. All of these patients underwent radioguided node biopsy, and a total of 12 lymph nodes were removed. The average diameter of the resected nodes was 8 (range 4-20) mm. No serious complications occurred. In three patients, metastases were identified in the lymph node.

Sentinel node biopsy is a more accurate method than clinical or radiological techniques to stage the disease of patients with anal carcinoma.