Study details
For the current study, the investigators analyzed data from all 2,887 breast cancer patients enrolled in the adjuvant BIG 2-98 trial. They compared the survival outcomes of those who received docetaxel-based chemotherapy with those who received non-docetaxel-based chemotherapy in relation to their BMI. Patients with a BMI of 18.5 to 25 kg/m were classified as lean; patients with a BMI of 25-30 were classified as overweight; and those with a BMI ≥30 were classified as obese.
The researchers also assessed a second-order interaction on the basis of treatment, BMI, and estrogen receptor (ER) status.
The results showed that in the overweight women, compared with lean women, the adjusted hazard ratios (HRs) for DFS and OS were 1.12 (95% CI, 98 – 1.50; P = .21) and 1.27 (95% CI,101 – 1.60; P = .04), respectively. For obese vs lean patients, the HRs for DFS and OS were 1.32 (95% CI, 108 – 162; P = .007) and 1.63 (95% CI, 1.27 – 2.09; P < .001), respectively.
The survival outcomes were similar when only those patients who received a relative dose intensity ≥85% for docetaxel were considered. However, when ER-negative and ER-positive tumors were considered separately, the researchers found evidence of a joint modifying role of BMI and ER status on treatment effect for DFS (adjusted P =.06) and OS (adjusted P = .04).
“[I]t appears that the benefit for docetaxel-based versus nondocetaxel-based treatment could be limited to lean and overweight patients with ER-positive tumors and, possibly, to lean patients with ER-negative tumors…,” Desmedt and colleagues comment.
It may even be possible that docetaxel-based treatment could be detrimental for overweight patients with ER-negative tumors, they note, but warn that these results should be interpreted with caution.
The investigators note that, worldwide, the proportion of women with increased adiposity has been increasing for decades. In Europe, it is estimated that more than 50% of women are overweight and obese. In the United States, almost 64% of women have a BMI >25 kg/mg2.
Previous studies have shown that, in postmenopausal women, a high BMI is associated with a higher risk of developing breast cancer and that, in women who do develop breast cancer, the prognosis is worse. In addition, a recent study demonstrated that increased adiposity can raise the risk for breast cancer in postmenopausal women whose BMI is in the normal range.
The study was funded in part by Fondation Cancer Luxemburg and Associazione Italiana per la Ricerca sul Cancro AIRC. Desmedt has disclosed no relevant financial relationships. A number of study coauthors reported relationships with industry.
This story first appeared on Medscape.com.