Pelvic sentinel lymph node biopsy in melanoma patients: is it worthwhile?

The original procedure of intraoperative lymphatic mapping by using vital blue dye initially described by Morton and colleagues in 1992 was implemented in subsequent years by the introduction of preoperative lymphoscintigraphy (LS) and intraoperative gamma detection probe to allow a better identification of sentinel nodes (SNs). However, it is common, in practice, to detect more than one radioactive node with the gamma detection probe. Whether these additional lymph nodes represent true SNs is not yet clear. The aims of this study are: to investigate the role of pelvic sentinel node biopsy in recurrent pelvic disease in those patients with negative inguinal SN, having one or more deep hot spots identified by preoperative LS (follow-up group). One hundred and four stage I/II melanoma patients with primary tumor of the lower limb and lower trunk were enrolled in a restrospective study at the European Institute of Oncology, Milan, Italy, between 2000 and 2007. All patients presented hot spots both in superficial (groin) and deep (iliac-obturator) areas during dynamic LS. The study population consisted of 35 men and 69 women with a median age of 57 years at the time of diagnosis. The median follow-up period was 49 months (SD 22.4; range, 10-98 months). Of the 104 patients, 83 had a negative SN (80%). All sentinel-lymph-node-positive patients underwent superficial and deep inguinal dissection. Two patients (2.4%; 95% confidence interval: 1.5-8.8%) with negative SNs had pelvic recurrence. Among patients who underwent ilioinguinal dissection, three (14%; 95% confidence interval: 4-35%) had positive pelvic lymph nodes. After a 60-month follow-up, 79% of patients were alive and 66% were disease free. In SN-negative patients, disease-free survival was 69% and in SN-positive patients 53%. No significant difference was found by SN status (log-rank P values 0.15). Even if the sample size of our study cannot bring to conclusive results, and further studies are needed, it might be possible that harvesting pelvic SN in those patients with pelvic hot spots at LS could modify the natural history of melanoma patients in terms of pelvic recurrence and disease free survival. We recommend to improve our knowledge in the role of pelvic sentinel node in the natural history of melanoma.