(ChemotherapyAdvisor) – Sentinel lymph node biopsy (SLNB) provides prognostic information and is independently associated with improved survival in patients with Merkel cell carcinoma (MCC), results of a study concluded during the 66th Annual Society of Surgical Oncology (SSO) Cancer Symposium, held in National Harbor, MD.

While the utility of SLNB in melanoma and breast cancer has been defined as a result of well-designed, randomized clinical trials, to date, data are lacking for MCC, a rare, cutaneous neuroendocrine tumor. To define SLNB staging and therapeutic value for MCC, Swapnil D. Kachare, MD, of East Carolina University Brody School of Medicine in Greenville, NC, and colleagues used the Surveillance Epidemiology and End Results (SEER) tumor registry to compare patients who had undergone wide local excision with SLNB with wide local excision and nodal observation.

All patients undergoing surgery for MCC between 1980 and 2009 were identified; those patients with metastatic disease, incomplete staging, or clinically positive lymph nodes were excluded.

Of the 5,390 patients identified, 1,636 met inclusion criteria; 556 had undergone SLNB with wide local excision and 1,080 wide local excision and nodal observation. Among the patients who underwent SLNB, 75.9% had negative nodes and 24.1% had positive nodes. Median age was 77 years; 94.7% were white and 59.4% were male. “A total of 64.1% of patients had T1-stage tumors and 45.4% underwent radiotherapy,” the investigators reported.

They found that on univariate analysis, patients who had undergone SLNB were more likely to be younger (73 years vs. 80 years; P<0.001); have stage T1 disease (68.4% vs. 61.9%; P=0.01); and treated with radiotherapy (55.9% vs 40%; P<0.001). On logistic regression, age (P<0.001) and T1 status (P=0.02) maintained significance.

Overall median survival was 48 months in the SLNB group. Improved survival (107 vs. 40 months; P<0.001) was observed with a negative SLNB. Increased survival was found on univariate analysis for patients who had undergone SLNB with wide local excision (89 months) compared with wide local excision alone (39 months; P<0.001) as well as for female gender (72 vs. 42 months; P<0.001), radiotherapy (57 vs. 43 months; P<0.001), lower T-stage (P<0.001), and non-African American race (P=0.04).

On multivariate Cox regression, diminished survival was noted for observation (relative risk [RR], 1.47; 95% CI: 1.24-1.76; P<0.001) and confirmed the prognostic factors of male gender, omission of radiation, higher T-stage, and African American race.

Dr. Kachare recommended that SLNB be considered in all patients with nonmetastatic, negative lymph node MCC.

The abstract (#53) for this presentation is available at the 66th Annual SSO Cancer Symposium’s website.