Possible immunological implications of an association between the stages of first and second independent breast cancers.

Concepts regarding cell-mediated immunity and breast cancer are reviewed. Patients having in situ breast cancers have been found by in vivo and in vitro measurements to have cell-mediated immunity to autologous and homologous in situ breast cancer tissue which may last for some time after diagnosis. These observations suggest that antigenically similar cancers arising subsequently in the contralateral breast should be less likely to progress beyond the in situ stage and, if they do become invasive, should exhibit prognostically favorable signs of cell-mediated immunity, e.g. sinus histiocytosis in the lymph nodes and/or lymphoid infiltrate and perivenous lymphoid infiltrate associated with the primary tumor. Cell-mediated immunity has also been shown to be negatively associated with the stage of disease at diagnosis for invasive cancers, i.e. the proportion of patients exhibiting cell-mediated immunity decreases as the stage at diagnosis increases. These observations suggest that the stages of independent breast cancers occurring in the same woman should be positively correlated. Data from the SEER Program of the National Cancer Institute were examined in this regard and a strong positive association between the stage of first and second independent primary breast cancers was found with the effect on the stage of a second breast cancer following a the first invasive breast cancer appearing to decrease with time subsequent to diagnosis. These observations are consistent with the immunogenicity of breast cancer.