Indications for elective groin dissection in clinical stage I patients with malignant melanoma of the lower extremity treated by hyperthermic regional perfusion

From 1973 through 1979, inguinal node biopsy was performed to stage the disease process in 179 clinical Stage I patients with malignant melanoma of the lower extremity, who were all treated by hyperthermic regional perfusion as well. Of the 179 tumors, 12% were intermediate risk (0.75-1.44 mm) and 88% were high risk (greater than or equal to 1.5 mm); all had a Clark level of IV or V. The Rosenmuller node at the caudal margin of the saphenous hiatus was elected for inguinal node biopsy. This biopsy supplies a fair amount of information about the entire inguinal node region: a malignant node was found in 16 patients (9%); no other metastatic nodes were found in 11 (73%) of 15 subsequent therapeutic node dissections; the 16th had metastatic parailiac nodes as well. Two patients of the remaining 163 had only metastatic parailiac nodes, without metastatic inguinal nodes. Of the remaining 161 histologic Stage I patients, 23 (14%) developed inguinal node metastases in the course of the follow-up. In 17 (74%) these metastases occurred within 2 years of perfusion. Ten of the 23 showed simultaneous general metastases. The vast majority of the inguinal node metastases developed in patients with a tumor greater than or equal to 5 mm. The 5-year survival was 81%, i.e. 84% in females versus 69% in males, the difference being significant (P less than 0.01). A tumor thickness greater than or equal to 5 mm implied a significantly less favorable prognosis as to development of inguinal node metastases associated with general metastases than a tumor thickness less than 5 mm. The benefit of the inguinal node biopsy was related to the difference in 5-year survival between the group with inguinal node metastases at perfusion (69%) and the group who developed inguinal node metastases during the follow-up (24%). The difference was great (45%) but statistically not significant. The data seem to warrant the conclusion that, after perfusion therapy, inguinal node biopsy is sufficient to stage the disease process at a tumor thickness less than or equal to 5 mm. Given a tumor thickness less than or equal to 5 mm, elective groin dissection might improve the chance of survival.