Absolute lymphocyte count decreases with disease progression and is a potential prognostic marker for metastatic breast cancer

Purpose: Peripheral blood parameters such as the neutrophil-to-lymphocyte ratio (NLR) are prognostic markers for breast cancer patients. For instance, patients with a high NLR have a poor prognosis. Meanwhile, high absolute lymphocyte count (ALC) is reportedly a predictive factor for some chemotherapies. However, the underlying mechanisms behind how these markers relate to patient outcomes and how these markers change during the clinical course of patients with metastatic breast cancer (MBC) remains unknown.

Methods: We retrospectively investigated 156 patients who were treated for MBC and eventually transitioned to best supportive care (BSC) at our hospital between January 2017 and December 2021. Changes in peripheral blood parameters during MBC treatments and their association with patient outcomes were examined.

Results: From the time of MBC diagnosis (baseline) through to the transition to BSC, ALC became significantly lower, while the NLR and platelet-to-lymphocyte ratio (PLR) became significantly higher (p < 0.001 for all). This association was independent of hormone receptor status. Cox proportional hazard modeling found patients with hormone receptor-negative and a lower baseline ALC had a significantly shorter overall survival (p = 0.030 and p = 0.019, respectively).

Conclusion: We observed that peripheral blood markers gradually changed with MBC disease progression. Our data suggest that baseline ALC may be a potential prognostic marker after recurrence.