It's hard to say. There was a recent study demonstating effectiveness for women taking Tamoxifen. However, TNBC is much different. Coffee is also relatively high in cystine. Cystine deprivation has caused TNBC cell death in the laboratory setting. Check out: Blocking Key Nutrient May Treat Aggressive Form of Breast Cancer, Study Suggests. Most meats and some fish have relatively high levels of cystine.