P5-18-10: Utilisation of Primary and Secondary G-CSF Prophylaxis Enables Optimal Dose Delivery of Standard Adjuvant Chemotherapy in Early Breast Cancer: Results of 1655 Patients from a Single Institution.

Abstract

Abstract Background: Chemotherapy for early breast cancer (EBC) confers significant survival advantages. However, myelosuppression is a common cause of chemotherapy dose reduction that may subsequently compromise survival benefits. Primary prophylaxis (PG) with granulocyte-colony stimulating factor (G) is indicated for TAC regimen, but rates of grade 3/4 neutropenia (G3/4N) associated with other adjuvant regimens in a non-trial setting are not well documented. Optimal use of G will likely enable planned dose delivery, leading to optimal BC outcomes. This retrospective study reports dose delivery outcome with judicious use of G in a single institution. Methods: Consecutive patients (pts) with EBC who received chemotherapy at Mount Hospital from January 1999 — December 2010 were included. Data was collected prospectively for pt characteristics, regimen given and neutropenic complications. Only pts who received a minimum of 1 cycle of chemotherapy were included. PG was only available in pts receiving TAC after 1/4/2007; Secondary G prophylaxis (SG) was given for G3/4N in first cycle, febrile neutropenia (FN) or delay in neutrophil recovery (DN). Primary outcome measure was dose delivery defined as relative dose intensity (RDI — fraction of dose per unit of time of standard regimen) and fraction planned dose received (PDR). Secondary endpoints included EBC outcome and incidence of haematological malignancies. Results: Over the 12-yr period, 1655 pts (62% node positive) with mean age of 51yr (24-88yr) were included. Chemotherapy given — n(%): Non-anthracycline(A)/taxane(T) 63(3.8); A 671(40.5); AT 666(40.2); T-only 255(15.4). Overall 64% of pts received G: PG given for TAC in 167(10); SG was given for first cycle G3/4N 677(41), FN 87(5) — 89% during first cycle, DN 109(7). Mean RDI and PDR was 0.97 v 0.95 and 0.98 v 0.97 for pts who received G and did not, respectively. Amongst pts aged < or ≥65yr, rate of G use and >85% PDR were comparable (65% v 66%; and 4% v 6%, respectively). Five cases of myelodysplasia or acute leukaemia were reported (4 pts received G) — 0.37% v 0.17% of pts having G or not, respectively. All cases received an anthracycline with cyclophosphamide. At median follow-up of 44.9 months [Q1: 25.1- Q3: 69.6], DFS was 88.9% and OS 92.6%. PDR <85% occurred in 5% pts, with OS of 78% v 93% if pts received < or ≥85%, respectively. Discussion: Significant rates of myelosuppression occur with regimens commonly used in the community. These regimens are not associated with FN rates >20% and thus PG is not advised. Routine monitoring of first-cycle neutrophil nadir enabled the identification of those pts at high risk of developing further neutropenic complications and consequent need for dose reduction or delay. Utilisation of G in these high risk pts enabled a high RDI to be delivered, comparable to pts who did not experience significant myelosuppression. Further, pts who did not develop significant first cycle myelosuppression were largely spared the need for G. In this manner, concerns regarding haematological toxicity and costs associated with G use are minimised. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-18-10.