CDK4/6 Inhibitor-Associated Mean Corpuscular Volume Change: A Potential Parameter for Predicting Survival in Metastatic Breast Cancer?

ABSTRACT

OBJECTIVE: To evaluate the impact of CDK4/6 inhibitors on erythrocyte mean corpuscular volume (MCV) change and its possible correlation with progression-free survival (PFS) and overall survival (OS). STUDY DESIGN: Observational study. Place and Duration of the Study Department of Medical Oncology, Kahramanmaras Necip Fazil City Hospital, Kahramanmaras, Turkiye, between January 2020 and 2023. METHODOLOGY: The data of 74 patients with HR (+) HER2 (-) metastatic breast cancer were analysed retrospectively. MCV and other complete blood count metrics were noted before and after the treatment. The first post-treatment evaluation was performed at three months. The median ΔMCV values at the third month after treatment-baseline were calculated. RESULTS: The patients were all females, with a median age of 55 years (between 35 and 80). Prior to the therapy, the baseline median MCV level was 90.4 (min-max 77.3-113.2). After three months, the median MCV level was 95 (min-max 84.3-115.3). Moreover, 7.15 was the median ΔMCV level. Regarding PFS (16.53 vs. 15.26 months) (p = 0.13) and OS (21.46 vs. 17.83 months) (p = 0.08), there was no statistically significant difference seen between the group with ΔMCV ≥7.15 and the group with ΔMCV <7.15. CONCLUSION: CDK4/6 inhibitors led to an increase in MCV but there was no significant difference between PFS or OS and the increase in MCV. To figure out whether the rise in MCV represents a prognostic or predictive marker, further research is required. KEY WORDS Breast cancer, CDK4/6 inhibitors, Mean corpuscular volume, Prognosis.