Impact of adjuvant chemo- and radiotherapy on the cellular immune system of breast cancer patients.

The relevance of an uncompromised immune system for the development and progress of breast cancer still is a matter of intensive research. The impact of chemo- and/or radiotherapy on peripheral blood immune cell counts and activity of breast cancer patients (n=660) was investigated by flow cytometry. Not only the absolute counts, but also the comparison of those counts with standard values were evaluated. Most studies do not consider this comparison. As compared to pre-treatment values, leukocytes, lymphocytes, B-lymphocytes, T-lymphocytes, helper T-cells and CD25(+) T-cells (activated T-cells) were significantly reduced after chemo- and/or radiotherapy. However, mean cell counts remained within the normal range. Statistically non-significant down-regulation was detected for cytotoxic T-cells, suppressor T-cells and natural killer cells, which are of prime importance as far as tumor development and defence are concerned. The impact of the therapy is not predictable for individual cases. However, only less than 20% of the breast cancer patients were immunocompromized after chemo- and/or radiotherapy.