Background: Capecitabine is an oral fluoropyrimidine derivative which is frequently used alone or incombination regimens for the treatment of metastatic breast cancer. Although overall and progression freesurvivals have increased in recent years with the use of new generation drugs, predictive factors that wouldfurther improve the outcomes are needed. Previous studies have demonstrated the relation between posttreatmentincrease in mean corpuscular volume (MCV) and predicting therapy response as well as survival.The present study investigated the clinical impact of MCV elevation in metastatic breast cancer patients treatedwith capecitabine. Materials and
Methods: The data of a total of 82 patients from three centers followed betweenJune 2005 and June 2013 were retrospectively analyzed. The demographic data and hormone receptor statusof the patients, as well as initial examination before and after treatment and data concerning progression wererecorded. MCV ≥100 fl was considered as macrocytosis. Capecitabine was given at a dose of 2500 mg/m2 dailyfor 14 days every three weeks. Pre-treatment and post-treatment MCV and other parameters of complete bloodcount were recorded. Post-treatment initial evaluation was performed after 2 cycles of therapy.
Results: Themedian age of the patients was 46.5 years (range 26-72 years) and 54% were premenopausal. Performance statuswas ECOG 0 and 1 in 81 (99%) patients. The median number of cycles for capecitabine therapy was 5 (minmax:2-18). The median ΔMCV level (post-treatment values at sixth week - baseline) was 6.4. Whilst ΔMCVwas ≥6.4 in 42 patients, it was <6.4 in 40 patients. Clinical benefit (complete response+partial response+stabledisease) was observed in 37 (88%) of 42 patients with a median ΔMCV ≥6.4 and in 30 (75%) of 40 patientswith ΔMCV <6.4 with no statistically significant difference (p=0.158). No significant difference was determinedbetween the group with ΔMCV ≥6.4 and the group with ΔMCV <6.4 in terms of progression-free survival (11 vs12 months) (p=0.55) and overall survival (20 months vs. 24 months) (p=0.11).
Conclusions: The identification ofnew predictive markers in metastatic breast cancer is very important. In some recent studies, increase in MCVhas been suggested as a marker in tumor response. In the present study, however, no significant difference wasdetermined between tumor response and increase in MCV. Further studies including higher numbers of patientsare needed to determine whether increase in MCV is a predictive marker or not.