T-cell homeostasis in breast cancer survivors with persistent fatigue

Approximately 30% of women successfully treated for breast cancer suffer persistent fatigue of unknown origin. Recent studies linking inflammatory processes to central nervous system-mediated fatigue led us to examine cellular immune system status in 20 fatigued breast cancer survivors and 19 matched non-fatigued breast cancer survivors. Fatigued survivors, compared with non-fatigued survivors, had statistically significantly increased numbers of circulating T lymphocytes (mean 31% increase, 95% confidence interval [CI] = 6% to 56%; P = .015 by two-sided analysis of variance [ANOVA]), with pronounced elevation in the numbers of CD4(+) T lymphocytes (mean 41% increase, 95% CI = 15% to 68%; P = .003 by two-sided ANOVA) and CD56(+) effector T lymphocytes (mean 52% increase, 95% CI = 4% to 99%; P = .027 by two-sided ANOVA). These changes were independent of patient demographic and treatment characteristics. Absolute numbers of B cells, natural killer cells, granulocytes, and monocytes; were not altered. The increased numbers of circulating T cells correlated with elevations in the level of serum interleukin I receptor antagonist (for CD3(+) cells, r = .56 and P = .001; for CD3(+)/CD4(+) cells, r = .68 and P < .001, by Spearman rank correlation). Results of this study suggest that persistent fatigue in breast cancer survivors might be associated with a chronic inflammatory process involving the T-cell compartment. These results require confirmation in a larger study that is specifically designed to address this hypothesis.