Controversy remains about the role of sentinel lymph node biopsy in the management of thin, or early, melanoma. Dermatology Times asked two experts to weigh in.
DT: What is the survival benefit, if any, in sentinel node biopsy in early melanoma?
In 2006, the five-year follow-up data was published (Morton DL, et al. N Engl J Med. 2006;355:1307-1317), with 1,269 patients with an intermediate-thickness primary melanoma enrolled in the study. At this time, the study confirmed a five-year disease-free survival rate advantage in the SLNB arm (78.3 percent) over the observation arm (73.1 percent).
While the give-year melanoma specific survival rates were similar in the two groups (87.1 percent and 86.6 percent, respectively) the five-year survival rate among patients with nodal metastases was higher in patients who underwent immediate lymphadenectomy when compared to those in whom lymphadenectomy was delayed (72.3 percent vs. 52.4 percent).
The 10-year follow-up data (fourth interim analysis) of the MSLT-1 was presented at the Society of Surgical Oncology's 63rd Annual Cancer Symposium in March. The melanoma-specific survival for all randomized patients with trunk and extremity primary melanomas was 78.1 percent for SLNB vs. 71 percent for the observation group, demonstrating an overall advantage to complete SLNB and lymphadenectomy in primary cutaneous melanomas.
Dr. Zitelli: There is no survival benefit in doing a sentinel lymph node biopsy and then doing a complete node dissection for those whose sentinel nodes are positive. That is a hard fact to swallow, because we all want to believe that the earlier we can identify and treat cancer, even metastatic cancer, the better it is for the patient. However, in the MSLT-1 study that was designed to answer this question about survival, the results showed emphatically that there was no survival benefit compared to just removing lymph nodes when they became palpable.
DT: Is there a better way than sentinel node biopsy to prognosticate in early melanoma? For example, can scanning techniques such as PET scan substitute for a sentinel node biopsy?
Dr. Curiel: To date, SLNB is the strongest predictor of survival, with an average false negative rate of about 3 percent and approximately 15 percent to 35 percent of melanoma patients with clinically negative nodes, demonstrating SLNB positivity overtime. Current imaging techniques, such as PET or high-resolution ultrasound, do not substitute for the SLNB procedure, since these studies still have significant limitations to detect micrometastatic disease.
Risk of nodal metastasis varies with tumor thickness: