Sentinel node biopsy in melanoma using technetium-99m rhenium colloid: TheLondon experience

Nodal metastases in patients with melanoma identify a reduction of survival by 50%; however, elective lymph node dissection (ELND) has not been shown clearly to improve survival. Morton's technique of sentinel node biopsy, us ing preoperative lymphoscintigraphy and intraoperative blue dye, addresses elegantly the controversy regarding ELND, Sentinel node biopsy has been sho wn to stage the patient accurately because metastases from melanoma follow an orderly progression from the sentinel node to the remainder of the basin . Fifty-six consecutive patients with American Joint Committee on Cancer st age Ib or 2 melanoma seen at the London Health Sciences Center between July 1998 and January 2000 were enrolled prospectively to undergo sentinel node biopsy. Preoperative lymphoscintigraphy was conducted in the nuclear medic ine department. A total of 10 to 15 MBq (0.27-0.41 mCi) of technetium 99m ( (TC)-T-99m) rhenium colloid or filtered sulfur colloid was injected intrade rmally around the biopsy scar, images were obtained to localize all drainin g nodal basins. The location of the sentinel node was marked on the skin. T he patient was taken to the operating room and anesthetized. Isosulfan blue dye was injected intradermally around the biopsy scar. A hand-held gamma p robe was used intraoperatively as a guide to the first draining node. Blue- stained lymphatic channels aided in the dissection. Sentinel node localizat ion was successful in 55 of 56 patients, for an overall success rate of 98% . Preoperative lymphoscintigraphy identified a sentinel node in an unpredic table location in 32% of patients. On average, 2.3 sentinel nodes per patie nt were identified on the initial scan, and 2.2 sentinel nodes per patient were recovered at surgery. Both Tc-99m rhenium and filtered sulfur colloid showed no substantial differences in tracer uptake and retention in the sen tinel node. Twelve patients had a positive sentinel node on routine histolo gy, and 11 patients subsequently underwent completion lymphadenectomy. The mean thickness of the primary melanoma in the 12 patients with positive sen tinel nodes was 3.7 mm compared with a mean tumor thickness of 1.8 mm in th e remaining 41 patients with negative biopsies (p = 0.0003), Two patients e xperienced recurrence in a regional basin after negative pathological evalu ation of the sentinel node. Reverse transcription-polymerase chain reaction analysis of both of these patients was positive. Two patients are alive wi th metastatic disease and 54 patients are alive without disease, with a mea n follow-up of 1 year (range, 2-24 months). Complications occurred at a sub stantially higher rate (45%) after completion lymphadenectomy than after se ntinel node biopsy alone (9%). Sentinel node biopsy is a feasible technique with a high success rate (98%), but it requires a multidisciplinary approa ch. This study validates the clinical usefulness of Tc-99m rhenium colloid for lymphoscintigraphy.