Sentinel lymph node biopsy in patients with primary cutaneous melanoma: study of 455 cases

Background The role of elective lymph node dissection in the treatment of p atients with primary melanoma is a debated topic in surgical oncology. Howe ver, recent data assure a survival improvement with this technique only for patients harbouring nodal metastases. The emergence of a new procedure of lymphatic mapping permits the identification of the sentinel lymph node (SL N), the first draining node from the site of cutaneous melanoma, which has demonstrated to be predictive of staging of the entire regional lymphatic b asin and useful in selecting for lymph node dissection only those patients who have early micrometastases. Objectives To verify in a large series of cases whether a combination of pr eoperative lymphoscintigraphy and intraoperative mapping with both vital bl ue dye and a hand-held gamma probe would permit an increase of the rate of successful SLN localization up to 100%; to check the utility of a wider app lication of SLN biopsy in patients with thin melanomas owing to a favourabl e risk-benefit ratio; to determine the predictive value of SLN biopsy by pe rforming regional lymphadenectomy in patients who have pathological evidenc e of metastases in the SLN; to observe whether the use of SLN technique and selective lymphadenectomy might improve the clinical evolution of patients and favour low rates of recurrence. Methods In 425 AJCC stage I or II melanoma patients, preoperative lymphosci ntigraphy by intracutaneous injection of Tc99m-labelled albumin nanocolloid s around the tumour or the tumour's excision scar was combined with the int raoperative use of a hand-held gamma probe and patent blue V mapping techni que, in order to identify and harvest the SLN. In five cases the blue dye w as voluntarily not used because of previous allergic reactions. In other 25 preliminary cases the procedure was performed using the blue dye alone (10 cases) or combined with a preoperative lymphoscintigraphy (15 cases). A wi de excision of the primary site was then undertaken in all cases. SLNs were sent to the pathologist for serial sectioning and permanent preparations w ith histological and immunohistochemical examination. Patients with patholo gical evidence of metastatic disease in SLN returned for regional lymphaden ectomy. Results The combined use of lymphoscintigraphy, blue dye and gamma probe al lowed us to identify one or more SLNs in all cases except for two (99.5% ra te of success). In 70 melanomas less than 0.76 mm thick, SLNs were negative for metastases, whereas in 380 patients with thicker tumours micrometastas es were demonstrated in 75 cases (19.7%). In patients with SLN metastases w ho underwent regional lymph node dissection, no other metastases were found three times out of four. After a median follow-up period of 18 months the rate of recurrence of the disease in 335 patients with SLN free of metastas is was low (5.4%) with a very low regional nodal recurrence (1.2%). Moreove r, the worsening of the disease did not exceed 18.5% of cases with metastas is in SLN. Conclusions Our data confirm in a large series of cases that the SLN biopsy is extremely selective and useful to find early micrometastases and to ide ntify patients needing regional lymphadenectomy and adjuvant immunotherapy Patients with intermediate thickness melanoma (0.76-4.0 mm) should be infor med on the availability of such a revolutionary procedure, which represents a new opportunity in primary melanoma surgery.