Tryptophan metabolism in women with breast cancerIn women with breast cancer, there is a disturbance of the tryptophan-niacin pathway. Rose and Sheff (1967) have studied tryptophan metabolism in this disease and found that half of all patients excreted abnormally elevated levels of an intermediary metabolite, kynurenine, after tryptophan loading. Brown and Davis (1969) con$rmed this jnding. Because women with the tryptophan metabolism abnormality and breast cancer have a better prognosis than those without the abnormality (Bell et al., 1975) and because the presence of estrogen and progesterone receptors in the tumor confers a better prognosis as well (McGuire and Clark, 1986}, we studied the relationship of the tryptophan abnormality to the hormone receptors. Women with stage 1 or II breast cancer were recruited for this study. They were given a 2g loading dose of L-tryptophan orally, and then they collected their urine for 24 hr. Urinary kynurenine was assayed by the method of Arend et al. (1970):of subjects Ky nurenine (pmol/day) ER-PR-ER+PR-ER+PR+ 15 10 14 34.16 f 26.7 13.2 f 6.01 15.6 16.6 F = 5 . 3 1 ,~ < 0.01 (o.w. ANOVA)
The elevated kynurenine excretion in E R f P R f women may be due to activation of the immune system. Some preliminary studies by one of us (R.R.B.} have indicated that normal subjects, injected with interferon or interleukin, have high kynurenine excretion after a tryptophan load. Also, upper respiratory infections, which activate the immune system, increase kynurenine excretion. Thus, our$nding of high kynurenine excretion in women with both receptors may indicate increased immune reaction against the tumor and perhaps even a better prognosis.Yours sincerely, January 12, 1988 REFERENCES AREND, R.A., LEKLEM, J.E., and BROWN, R.R., Direct and steam distil-BROWN, R.R., and DAVIS, H.L., Tryptophan metabolism and hormonal lation autoanalyzer methods for assay of diazotizable aromatic amine response in breast cancer patients. Proc. Amer. Ass. Cancer Res., 10, 10 metabolites of tryptophan in urine and serum.phan metabolism and recurrence rates of patients with breast cancer after ROSE, D,p., and sHEFF, M.D., ~~~~~~h~~ metabolism in carcinoma of mastectomy.
