ExogenousMLT may influence nuclear grade and/or estrogen receptor activity in breast cancer patients.

Combination with Tamoxifene plus Melatonin (20 mg day) may have some benefit in untreatable metastatic solid tumour patients.

Combined therapy of melatonin (200 microg/day, p.o.) and tamoxifen is highly promising in the prophylaxis of breast carcinogenesis in humans.

Breast cancer women had a reversal of the normal seasonal pattern of melatonin secretion.

Melatonin (10(-9) M) and tamoxifen (10(-7) M) may act through different biological pathways to down-regulate cell growth.

Concomitant administration of MLT during chemo-therapy may prevent some chemotherapy-induced side-effects,

Melatonin could indeed be considered a physiological anticancer substance.

10 microM L-buthionine-[S,R]-sulfoximine(L-BSO) blocks the oncostatic action of 1nM melatonin, glutathione(1microM) is required for melatonin action.

Decreased pineal melatonin secretion in breast cancer patients as well as an inverse relationship with tumor-size.

Yet unknown chemical structure are capable of inhibiting in vitro cell lines resistant to melatonin.