Natural remedy use in a prospective cohort of breast cancer patients in southern Sweden

Abstract

Background. Complementary and alternative medicine (CAM) use is common among breast cancer patients. Several CAM therapies may have negative side effects or interact with conventional therapies. We studied biologically based CAM use with and without vitamins/minerals in relation to patient and tumor characteristics as well as treatment in an ongoing prospective cohort of 855 primary breast cancer patients. Methods. Patients from two hospitals in southern Sweden were included. Pre-operative and follow-up questionnaires containing questions on food intake, lifestyle, and concomitant medications, including natural remedies, were completed up to five years postoperatively. Clinical information was obtained from clinical records and tumor characteristics from pathology reports. Results. CAM and/or vitamins/minerals were used by 34.2% pre-operatively and by 57.9% during at least one visit. Over 100 different preparations were reported. At least eight of the commonly used preparations may interact with conventional breast cancer therapies. CAM users more often had a BMI <25 kg/m² (OR 1.76; 95%CI 1.33–2.33), were more often nulliparous (OR 1.59; 1.08–2.34), alcohol (OR 2.13; 1.44–3.14), antidepressants (OR 1.48; 1.02–2.15), and hormone therapy users (OR 1.57; 1.18–2.07), less often smokers (OR 0.71; 0.50–0.99), and consumed less coffee (OR 0.88; 0.82–0.95) than non CAM users. Tumor characteristics were not associated with CAM use. CAM use was more common among tamoxifen (OR 1.32; 1.00–1.75) and less common among chemotherapy (OR 0.63; 0.42–0.92) treated patients. Vitamins/minerals use was more common in aromatase inhibitor treated patients (OR 1.84; 1.33–2.53). There was no significant association between short-term disease-free survival and CAM use. Conclusion. CAM use was common and associated with certain patient characteristics. CAM use may cause clinically significant drug interactions and it is therefore of clinical interest to identify potential CAM users.