The authors study the amount of B cells and serum immunoglobulins in patients with mammary cancer or fibrocystic disease. They indicate that a decreasing in B cells and IgG, and an increasing in IgA are associated with a better prognosis. There is an inverse relation between the level of serum IgG and the blastic transformation of T cells by PHA, what is an indirect measure of the circulating IgG immune complexes. The presence of B cells with IgG in their surfaces makes worse the prognosis.