The following is a summary of “Prognostic value of lymphocytes in patients with breast cancer receiving radiotherapy after breast-conserving surgery: A post hoc analysis of a phase III randomized trial,” published in the June 2024 issue of Oncology by Song et al.

This study aimed to assess the prognostic significance of peripheral lymphocyte count (PLC) in patients with breast cancer undergoing breast-conserving surgery (BCS) followed by radiotherapy (RT). Utilizing data from 628 participants in a phase III randomized controlled trial, which compared hypofractionated RT (HFRT) and conventional fractionated RT (CFRT) post-BCS, researchers conducted a post hoc analysis. PLCs were measured at multiple time points: before, during, and after RT, extending to a one-year follow-up. Optimal PLC thresholds were identified using the maxstat package in R, and survival outcomes were evaluated through the Kaplan-Meier method and log-rank test comparisons. 

Among the cohort, 275 patients (46.1%) experienced lymphopenia during RT, with 17 cases (2.8%) reaching grade 3 severity and none progressing to grade 4. Over a median follow-up period of 110.8 months, patients exhibiting pre-RT PLCs below 1.77 × 10⁹/L demonstrated significantly reduced 10-year breast cancer-specific survival (BCSS) (P = 0.013) and overall survival (OS) (P = 0.026). Additionally, a nadir PLC below 1.35 × 10⁹/L correlated with a notably poorer 10-year OS rate (P = 0.048). Multivariate analysis confirmed that a pre-RT PLC under 1.77 × 10⁹/L independently influenced BCSS and OS, though the nadir PLC’s impact did not retain statistical significance. Recovery of PLC at post-RT intervals of 1, 3, and 6 months and at one year showed no association with survival outcomes. 

In conclusion, radiation-induced lymphopenia in patients with breast cancer post-BCS is generally mild, yet lower pre-RT PLC serves as a predictive marker for poorer long-term survival. This finding underscores the importance of pre-treatment PLC as a prognostic factor and suggests that monitoring PLC could be integral to patient management strategies in breast cancer therapy.

Source: sciencedirect.com/science/article/abs/pii/S0167814024006601