Methylxanthine consumption is associated with the development of fibrocystic disease of the breast. Methylxanthine abstention is associated with resolution of signs and symptoms of fibrocystic disease. Abstinence from methylxanthine consumption decreased breast biopsies and the need for major breast surgery because of benign disease. Methylxanthine consumption is associated with elevated cyclic adenosine monophosphate (AMP) and cyclic guanosine monophosphate (GMP) values in fibrocystic dsiease over those obtained in normal breast tissue.