Differential effects of docetaxel-based chemotherapy according to body mass in patients with early breast cancer

The study investigated whether chemotherapy after surgery with or without docetaxel (Taxotere) has different outcomes in patients with different body mass indexes (BMI; a measurement of body weight in relation to height) and early breast cancer (BC). The main finding was that patients responded differently to docetaxel based on their BMI.

BMI measures the weight-to-height ratio. A BMI between 18.5 kg/m² and 24.9 kg/m² is considered normal, with higher values indicating overweight. Docetaxel has a higher affinity to body fat. It can work differently in patients with varying BMIs. Docetaxel is a chemotherapy drug used to treat BC. Adjuvant chemotherapy is given after initial treatment to lower the risks of relapse. However, the effectiveness of docetaxel-adjuvant therapy based on BMIs is not studied in clinical trials.

The study included 2887 women (younger than 71 years) with early BC. Based on BMI, 47.4% of patients were lean (normal BMI values), 33.5% were overweight (BMI of 25-29.9 kg/m²), and 19.1% were obese (BMI over 30 kg/m²). Patients who received docetaxel were compared to those who did not receive docetaxel in terms of survival.

Disease-free survival (DFS) was similar among patients with varying BMIs who did not receive docetaxel. DFS means how long patients survive without showing cancer symptoms. DFS decreased among overweight and obese patients compared to leans, in the docetaxel group. Overweight patients had 12% higher risk of a lower DFS compared to lean patients. Obese patients had 32% higher risks of lower DFS, compared to lean ones.

Overweight and obese women treated with docetaxel also had lower overall survival (OS) compared to lean women who took docetaxel. Being overweight was associated with a 27% risk of a lower OS and being obese with a 63% higher risk a lower OS compared to lean patients.

Estrogen receptor (ER) is a protein on BC cells that binds to the female sex hormone estrogen. Treatment differs between BC with and without ER. ER-positive BC responds to hormonal therapy. Treatment outcomes were similar across all BMIs among patients with or without ER in the non-docetaxel group. DFS and OS were lower in overweight and obese patients without ER in the docetaxel group. Among ER-positive patients receiving docetaxel, only obese women had lower DFS and OS compared to overweight and lean ones. Obese patients on docetaxel had 37% higher risks of relapse compared to overweight ones in the ER-positive group. They also had 59% higher risks of a lower OS.

The authors concluded that patients with early BC with increased BMI showed poorer outcomes to docetaxel-based adjuvant chemotherapy.

This study was retrospective, meaning that it looked back in time to reanalyze data from a trial. Information might have been incomplete. Additional real-life studies focused on such analyses are needed.