Caffeine and the development of the normal and neoplastic mammary gland

There has been much interest in the role of dietary factors in the etiology and progression of breast disease. Due to its wide consumption and the many biochemical and physiological effects it exerts, caffeine has been extensively examined in both clinical and experimental animal studies. To date, clinical studies investigating a possible relationship between caffeine consumption and breast disease in humans have yielded inconsistent and inconclusive results. In experimental animal studies utilizing laboratory mice and rats, caffeine has been shown to stimulate mammary gland lobulo-alveolar development and secretion. The development of mammary gland tumors can be either stimulated or suppressed depending upon the animal species and strain, and the stage of tumorigenesis (initiation/promotion) at which caffeine is administered. Many laboratories have proposed that antagonism of the adenosine receptor is the most plausible mechanism to account for the many biological activities of caffeine. However, other mechanisms by which caffeine act cannot be discounted. The significant modifying role of caffeine on normal and neoplastic mammary gland development in experimental animals provides a biological foundation from which to implicate caffeine as a potential modulator of developmental growth of normal, benign, and carcinomatous human breast tissues.