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Chemotherapy kills rapidly dividing cells including lymphocytes. However, little is known about the functional status of the remaining cells or of new lymphocytes produced during the treatment and recovery period. Exercise training during chemotherapy has been shown to have a positive effect on psychological well-being, and physical functioning. The goal of this study was to examine the effect of an exercise intervention following chemotherapy on long term lymphocyte activation. Methods: Breast cancer patients (N=28, mean age 48.5 yrs) who participated in a six month exercise program following treatment were compared with patients (N=29, mean age 52.3 yrs) who did not participate. Patients underwent fitness evaluations after therapy and met with a trainer for one-on-one sessions three times a week for six months. The training consisted of a 5 minute warm up, resistance training with elastic rubber bands, and approximately 20 minutes of aerobic activity at 60-75% functional capacity. Blood was taken at four times: before chemotherapy; after treatment, 3 months after ending treatment, or mid-exercise; and 6 months after ending treatment or post exercise. The activation of lymphocytes was determined by the presence of CD4+CD69+ cells (flow cytometry). BD True count tubes® were used to determine the absolute numbers of CD4+ cells present. Lymphocyte proliferation was determined by mitogen assays over a range of concentrations of the T cell activators PHA, and ConA, and the T and B cell activator PWM. Analysis of the exercising and non-exercising groups across the four time points was done using the Wilcoxon test. Comparisons between the breast cancer groups were performed with the Mann Whitney U test. Results: The patients in the formal exercise program showed an increase in fitness levels (increase in maximum oxygen uptake, respiratory rate, and upper body strength). Following the intervention, the exercisers had a significantly higher level of CD4+CD69+ T lymphocytes, as well as DNA synthesis (tritiated thymidine incorportation) with optimal concentrations of ConA, PHA or PWM. Conclusions: A six month exercise intervention resulted in greater T cell and possibly B cell activation in breast cancer patients following chemotherapy. This result suggests that although the total lymphocyte number remained low six months after therapy, the cells were more functional in breast cancer patients participating in a formal exercise program compared with those who did not. Research supported by the US Army Medical Research and Material Command, DAMD 17-98-1-8142, General Clinical Research Center of The Pennsylvania State University, NIH M01 RR 10732, The Penn State University’s President Fund for Research and NSF REU grant through the Pennsylvania State University Nutrition Department. IRB# 16051

[Proc Amer Assoc Cancer Res, Volume 46, 2005]