A new study has reported that chemotherapy and/or radiation treatment has a moderate impact on the immune system of breast cancer patients. The significance of an uncompromised immune system with respect to the development and progression of breast cancer is still a matter of intensive research and debate. In the study, the impact of chemotherapy and/or radiation treatment on peripheral blood immune cell counts were evaluated in 660 breast cancer patients. In addition to absolute counts, a comparison of the counts with standard values was made, an analysis which has not been made in most studies.

Compared to pre-treatment values, levels of lymphocytes, B-lymphocytes, T-lymphocytes, leukocytes, helper T-cells and CD25+ T-cells (activated T-cells) all were found to be reduced after chemotherapy and/or radiation treatment. However, average cell counts remained within normal ranges. Reduced activity was detected for remaining cytotoxic T-cells, suppressor T-cells and natural killer cells, cells which are of high importance as far as tumor development and defense are concerned. However, these reductions were not statistically significant. The impact of chemotherapy and/or radiation treatment was not predictable for individual breast cancer cases. Fewer than 20% of the breast cancer patients were immunocompromised after treatment.