Background An AC protocol followed by weekly paclitaxel (AC-PTXw) is a standard adjuvant treatment in women with operable breast cancer. Chemotherapy may produce neutropenia which can lead to dose delays and reductions in subsequent cycles and/or early termination of treatment, which in turn can cause a reduction in dose intensity (DI). Survival benefit is substantially  higher when DI ≥85% of the planned DI is received. The ability to identify patients at risk of not achieving the planned DI according to the occurrence of neutropenia during the first cycle might help guide appropriate haematopoietic growth factor use.

Purpose To evaluate the predictive value of cycle 1 neutropenia in the chemotherapy relative dose intensity (RDI) achieved by localised breast cancer patients receiving adjuvant treatment with AC-PTXw.

Material and methods All patients with early stage breast cancer treated with AC-PTXw were included. Dose and dates of administration of chemotherapy drugs were recorded to calculate received DI. Weight and height were also recorded to calculate body surface area suggested DI. Absolute neutrophil count on the blood test previous to cycle 2 was graded according to neutropenia severity.

Results In total, 194 patients were included (20 patients received only PTXw as anthracyclines were contraindicated). Myeloid growth factors were administered to 25% and 3% of patients during AC and PTXw phases, respectively. The occurrence of neutropenia after the first cycle was a statistically significant predictor for not achieving ≥85% RDI during both phases of treatment, especially when neutropenia was moderate or severe. Table 1 Risk of achieving RDI <85% depending on the occurrence of neutropenia in the first cycle AC PTX Any grade 48.5% vs 15% (OR 5.33, 95% CI 2.34 to 2.17) 64.3% vs 23.9% (OR 5.73, 95% CI 1.82 to 18.03) Grade ≥2 57.7% vs 15% (OR 7.75, 95% CI 3.15 to 19.06) 85.7% vs 25.6% (OR 18.39. 95% CI 2.16 to 156.79) Grade ≥3 68.7% vs 16.6% (OR 11.08, 95% CI 3.55 to 34.58)

None Conclusion The risk of not reaching programmed DI is greatly increased when neutropenia occurs during the first cycle. Clinicians should be aware of the fact that maximum benefit might not be obtained in those patients presenting neutropenia in the first cycle and should evaluate the whole treatment risk benefit ratio.

References and/or Acknowledgements

1. Wildiers H, Reiser M. Relative dose intensity of chemotherapy and its impact on outcomes in patients with early breast cancer or aggressive lymphoma. Crit Rev Oncol Hematol 2011;77:221-40

References and/or AcknowledgementsNo conflict of interest.