A breast cancer nutrition adjuvant study (NAS): Protocol design and initial patient adherence

Abstract

To evaluate the feasibility of using a reduction in dietary fat intake as a component of treatment regimens for patients with resected breast cancer, a multi-disciplinary cooperative group protocol was developed. Females 50 to 75 years of age with stage II breast cancer who completed primary local therapy were eligible for randomization to a Control Dietary Group in which dietary fat intake was to remain unchanged from baseline level (at approximately 38% of calories derived from fat) and an Intensive Intervention Dietary Group designed to reduce dietary fat intake. Both Dietary Groups were given tamoxifen 20 mg/day. To facilitate early experience with dietary regimen delivery, patients entered during an initial pilot phase could receive any chemotherapy and/or hormonal treatment. A prerandomization nutrition 'run-in' of clinically eligible patients assessed adherence to nutrition data collection procedures and screened patients for nutrition eligibility criteria. Of 59 patients beginning 'run-in', 49 were randomized and, at present, 32 have completed at least three months follow-up. The change in dietary fat intake (as assessed by Four Day Food Records) seen in both arms is outlined below. Formula see table. The 56% reduction in total daily fat gram intake achieved in the Intensive Intervention Dietary Group suggests that protocols designed to reduce dietary fat intake in an adjuvant treatment setting can be developed and implemented using a multi-institutional, cooperative group approach.

Adjuvant dietary fat intake reduction in postmenopausal breast cancer patient management

“…An increasing body of clinical experience suggests that women can achieve a substantial, sustained reduction in dietary fat intake in a clinical trial setting [5,15,36,56]. Mean dietary fat intake represents approximately 37% of total calories consumed by women in the United States at the present time [54].…”

“…Nonetheless, a moderate degree of weight loss was commonly observed [15,16,41]. For example, in American breast cancer participants of the Nutrition Adjuvant Study (NAS), a significant (p < 0.05) shortterm (3 month) weight loss of 2.9 kg was seen in patients assigned to the low-fat dietary intervention [16].…”

“…Mean dietary fat intake represents approximately 37% of total calories consumed by women in the United States at the present time [54]. Initial randomized trials directed at dietary fat intake reduction in a breast cancer context include a Toronto study in women with breast dysplasia [9,56], the Women's Health Trial (WHT) in women at increased risk for breast cancer [36,66], and of particular relevance to the current issue, the Nutrition Adjuvant Study (NAS) in American women with resected breast cancer [12,15,16] and a study of similar design in Norway [41]. All four independently conducted feasibility studies report a remarkably similar degree of reduction in dietary fat intake, to approximately 22% of total calories.…”

“…In the Nutrition Adjuvant Study experience of postmenopausal patients with resected breast cancer [12,15,16], the reduction in percent calories derived from fat was associated with significant reductions in daily intake of: total fat (g) 79. The Women's Health Trial has reported dietary intake changes of a similar magnitude and good dietary adherence for two years after initial fat reduction intervention in women at risk for breast cancer development [36].…”

Breast Cancer Chemoprevention: Clinical Trials and Research

“…Patients were randomized into two groups shortly after surgery: the control subjects were to con sume their customary diet, which characteristically con sists of 40% of calories as fat with a polyunsaturated:saturated:monounsaturatcd ratio of 0.4:1:1: the experimen tal group was to consume a modified diet based on a Japanese model, consisting of 20-25% of calories as fat with a P/S/M ratio of 1:1:1 [79]. The study will largely depend on how successfully patients achieve the desired level of fat intake [78,80,81], Eicosapentaenoic Acid ami Docosahexaenoic Acid. There is an inverse relationship between the incidence of breast cancer and the level of fish consumption, suggest ing a protective role of n-3 PUFAs against human breast cancer [82], Fish oils rich in n-3 fatty acids have been shown to inhibit tumor development in some animal models [83][84][85], possibly by interfering with prostaglan din metabolism [86,87], Fish oils invariably contain a mixture of fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).…”