Background Neutropaenia is one of the most common adverse effects of paclitaxel. It is dose-dependent and has dose-limiting toxicity. However, the American Society of Clinical Oncology (ASCO) guideline recommends the use of real bodyweight for chemotherapy dosing, irrespective of obesity.

Purpose The aim of the study was to assess the incidence of neutropaenia in obese patients treated with paclitaxel and to compare our results with those published in the summary of product characteristics (SmPC).

The secondary objective was to identify if dose reductions were related with the development of neutropaenia.

Material and methods Retrospective, observational, descriptive study of patients treated with paclitaxel from January to December 2017 at a second-level hospital. Data collected: age, sex, body surface area (BSA), body mass index (BMI), diagnosis, initial dose, grade of neutropaenia and dose reduction.

Obesity was considered from BMI ≥30 kg/m² and neutropaenia grade was classified based on the Common Terminology Criteria for Adverse Events, version 5.0.

Results A total of 186 patients were treated with paclitaxel, 31 were obese, 28 of them females. The average age was 65±7 years, BSA 1.8±0.1 m² and BMI of 34.14±3.14 kg/m².

The diagnoses of obese patients were: 19 breast cancer; four lung cancer; three ovarian cancer; two endometrial cancer, one pharyngeal cancer, one cervical cancer and one with gastric cancer.

In the weekly schedule, the initial dose in all patients was 80 mg/m². In the three-weekly schedule the initial dose was 175 mg/m² in five patients and 135 mg/m² in four patients.

Neutropaenia was developed in 19 (61%) patients, while in the SmPC was reported in 79% of patients: 10 patients grade I; five patients grade II and four patients grade III.

Dose reduction was needed in 17 patients: only three due to neutropaenia and the rest because of diarrhoea, asthaenia or neuropathy.

Conclusion In our study, obese patients did not develop more neutropaenia compared with the SmPC. Additionally, two-thirds of the patients needed dose reductions, but the majority of them are not related to neutropaenia. However, more studies are needed.

References and/or acknowledgements Griggs J, Mangu P, Anderson H, et al. Appropriate chemotherapy dosing for obese adult patients with cancer: ASCO Guideline. J Clin Oncol 2012; 30:1553–61.

No conflict of interest.