Long-term patient reported outcomes and hematologic toxicity among patients who received Granulocyte-Colony Stimulating Factors during chemotherapy for early breast cancer.

We assessed long-term associations of Granulocyte-Colony Stimulating Factors (G-CSF) use with patient-reported outcomes (PROs) and hematologic toxicity among chemotherapy-treated, early-stage breast cancer patients in CANTO (NCT01993498). Among 2920 patients longitudinally followed-up until year-4 after diagnosis, 49% used G-CSF. In multivariable-adjusted mixed-models, EORTC QLQ-C30 pain and summary score were not substantially different between groups (overall adjusted mean difference, use vs no-use [95%CI]: +1.27 [-0.33 to +2.87] and -1.01 [-1.98 to -0.04], respectively). PROs were slightly worse at year-4 among patients receiving G-CSF, although differences were of trivial clinical significance. No major differences were observed in leukocyte or platelet count over time.