An interesting case of possible abscopal effect in malignant melanoma

TLDR

Malignant melanoma has an unpredictable course, with lymph node involvement reducing five‑year survival to ~5 %, and while radiation is generally ineffective for metastases, rare reports of distant tumour regression—termed the abscopal effect—have been noted. The abscopal effect described here involves local irradiation inducing regression in the treated region while distant untreated metastases also regress, a pattern not previously documented. The case demonstrates an abscopal effect, a phenomenon common in leukemia but exceptionally rare in other cancers, making it noteworthy.

Abstract

The natural history of malignant melanoma is notoriously unpredictable. Although long-term survival is not uncommon (Cade, 1961), lymph node involvement lowers the five-year survival rate to about 5 per cent (Ackerman and Del Regato, 1970). It is generally accepted that radiation has no place in the treatment of metastases (Edwards, 1949; Kunkler and Rains, 1959) despite occasional reports of temporary tumour regression (Ellis, 1939; Sandeman, 1966). In these cases the response to irradiation occurred in the treated area and simultaneous regression of distant untreated metastases has never been reported. Such behaviour has been given the term "abscopal effect". It occurs not uncommonly in leukaemia but is extremely rare in other tumours and the case reported below is therefore of interest.