Not all women initiate clinically indicated breast cancer adjuvant treatment. It is important for clinicians to identify women at risk for noninitiation.

To determine whether complementary and alternative medicine (CAM) use is associated with decreased breast cancer chemotherapy initiation.

In this multisite prospective cohort study (the Breast Cancer Quality of Care [BQUAL] study) designed to examine predictors of breast cancer treatment initiation and adherence, 685 women younger than 70 years with nonmetastatic invasive breast cancer were recruited from Columbia University Medical Center, Kaiser Permanente Northern California, and Henry Ford Health System and enrolled between May 2006 and July 31, 2010. Overall, 306 patients (45%) were clinically indicated to receive chemotherapy per National Comprehensive Cancer Network guidelines. Participants were followed for up to 12 months.

Baseline interviews assessed current use of 5 CAM modalities (vitamins and/or minerals, herbs and/or botanicals, other natural products, mind-body self-practice, mind-body practitioner-based practice). CAM use definitions included any use, dietary supplement use, mind-body use, and a CAM index summing the 5 modalities.

Chemotherapy initiation was assessed via self-report up to 12 months after baseline. Multivariable logistic regression models examined a priori hypotheses testing whether CAM use was associated with chemotherapy initiation, adjusting for demographic and clinical covariates, and delineating groups by age and chemotherapy indication.

A cohort of 685 women younger than 70 years (mean age, 59 years; median age, 59 years) with nonmetastatic invasive breast cancer were recruited and followed for up to 12 months to examine predictors of breast cancer treatment initiation. Baseline CAM use was reported by 598 women (87%). Chemotherapy was initiated by 272 women (89%) for whom chemotherapy was indicated, compared with 135 women (36%) for whom chemotherapy was discretionary. Among women for whom chemotherapy was indicated, dietary supplement users and women with high CAM index scores were less likely than nonusers to initiate chemotherapy (odds ratio [OR], 0.16; 95% CI, 0.03-0.51; and OR per unit, 0.64; 95% CI, 0.46-0.87, respectively). Use of mind-body practices was not related to chemotherapy initiation (OR, 1.45; 95% CI, 0.57-3.59). There was no association between CAM use and chemotherapy initiation among women for whom chemotherapy was discretionary.

CAM use was high among patients with early-stage breast cancer enrolled in a multisite prospective cohort study. Current dietary supplement use and higher number of CAM modalities used but not mind-body practices were associated with decreased initiation of clinically indicated chemotherapy. Oncologists should consider discussing CAM with their patients during the chemotherapy decision-making process.