The predictive value of T-lymphocyte counts in breast cancer patients treated by endocrine manipulation

Endocrine manipulation has a valuable role in the management of advanced breast cancer. However, it is only effective in some cases and at least 12 weeks is required before efficacy can be ascertained. In an attempt to achieve earlier assessment of response, changes in lymphocyte counts have been studied in patients receiving endocrine therapy. Absolute lymphocytes were not significantly changed by 6 weeks in any patients but there was a significant increase (P less than 0.05) in absolute T counts by 6 weeks in patients who achieved partial remission when compared with those whose disease continued to progress. Percentage T counts increased significantly from pretreatment values (P less than 0.002) in patients in whom disease progression was stopped by endocrine manipulation and this rise was maintained during clinical benefit. Fall in percentage T counts to pretreatment values predated objective evidence of recurrence by as much as 2 months. There was no increase in percentage T counts in patients in whom disease progression continued despite treatment, indicating that the rise in percentage T counts is a secondary phenomenon to tumour response. T-lymphocyte counts may permit earlier evaluation of the patient during treatment, allowing earlier selection of alternative treatment modalities.