Effects of reducing the phenylalanine-Tyrosine intake of patients with advanced malignant melanoma

Abstract

Dietary means were employed to reduce the intake of phenylalanine and tyrosine in patients with advanced malignant melanoma. The rationale was that the large quantities of active tyrosinase in these tumors plays a vital respiratory role in pigmented melanomas. The limitation of substrate, i.e., tyrosine, might, therefore, result in selective energy deprivation with consequent inhibition of tumor growth. In 3 of the 5 patients studied there was a clear relationship between the institution of the dietary regimen and the onset of regressive changes in the metastatic disease. There was a further direct correlation between the serum phenylalanine and tyrosine levels and the progression of the disease. The course of a fourth patient suggests that the melanoma was suppressed during the time she was on the diet; upon her discontinuance of this regimen the disease started to spread. The fifth patient showed no regressive changes in her metastases in spite of adhering to the diet but her serum phenylalanine and tyrosine levels did not decrease during the several months that she was on the diet. This regimen, although beneficial with respect to some of the metastases and probably nutritionally sound, is cumbersome, complex and unpalatable, making its application difficult.