Association between immunity and prognostic factors in early stage breast cancer patients before adjuvant treatment

Objective: The association of known prognostic factors with immune cell counts and β₂-microglobulin and soluble IL-2 receptor (sIL-2r) serum levels as markers of activation of the immune system was investigated in breast cancer. Methods: Two hundred thirty five operated stage I and II breast cancer patients to receive adjuvant treatment in IBSCG trials were assessed in a cross-sectional study immediately before the first treatment. Leukocytes, lymphocytes and lymphocyte subset counts, β₂-microglobulin and sIL-2r serum levels were assessed as immunological parameters. Prognostic factors were tumor load, receptor status, patient characteristics, and contextual factors of the immune assessment (such as time of the day, time since surgery, type of surgery, concomitant medication, co-morbidity). Results: In an operated early stage breast cancer patient population, tumor load was not associated with immune cell counts, βn₂-microglobulin, or sIL-2r before adjuvant treatment. There was a pattern of association of prognostically favorable factors such as estrogen receptor (ER) positive tumor and older age with higher NK cell counts or with β₂-microglobulin or sIL-2r. In addition, immune cell counts and the markers of activation of the immune system were affected by several contextual factors, such as diurnal variability, time since surgery, type of surgery, and the intake of concomitant medication. Conclusions: The association of NK cell counts and β₂-microglobulin or sIL-2r serum levels with prognostically favorable factors such as ER positive tumor and older age supports the assumption that the immune system plays a role in the course of early breast cancer. The exact nature of this role requires further study.