The scope of nutrition intervention trials with cancer-related endpoints

Abstract

The National Cancer Institute currently is supporting three full‐scale dietary modification trials with cancer‐related endpoints. These studies are the dietary component of the Women's Health Initiative, designed to determine whether a low‐fat diet will reduce the incidence of breast and colorectal cancer and/or coronary heart disease; the Women's Intervention Nutrition Study, designed to test whether a dietary fat reduction program will decrease breast cancer recurrence and increase patient survival; and the Polyp Prevention Trial, designed to determine whether a low‐fat, high‐fiber diet will reduce the recurrence of adenomatous polyps. Design issues associated with these full‐scale dietary modification outcome trials have been addressed successfully in a series of feasibility studies. The ability to achieve a sustained reduction of 50% in dietary fat intake with maintenance of nutritional adequacy has been demonstrated in randomized trials of postmenopausal populations with resected breast cancer and in populations at increased risk for breast cancer. In these studies comparing dietary fat reduction programs with control lifestyles, a series of associated biologic changes, consistent with the self‐reported dietary alterations, have been observed. These changes include body weight reduction, serum and/or plasma estradiol concentration reduction, fasting plasma cholesterol concentration reduction, and alteration in free fatty acid levels. Such results provide a substantial basis for reliably estimating the level of adherence that can be anticipated in trials of dietary change, a prerequisite for appropriate calculation of the sample size needed for multicenter, full‐scale outcome studies. As a result, the efficacy of a series of dietary alterations (including fat reduction, fiber addition, and/or increased fruit and vegetable intake) on cancer‐related endpoints with potential major public health significance (breast cancer recurrence, breast cancer development, and colonic polyp recurrence) now are being addressed definitively in prospective clinical trials.

A lifestyle program for treated hypertensives improved health-related behaviors and cardiovascular risk factors, a randomized controlled trial

“…A greater increase in time spent in physical activity was found in the program group than with Table 2 Energy and nutrient intake at baseline, 4 months, and follow-up usual care at the end of 4 months and, although this was based on self-reports, which may be unreliable, data were obtained using a validated interviewer-administered method [19]. At baseline, 55% of the usual care group and 40% of the program group reported physical activity conforming to the guideline of at least 30 minutes per day on 5 days of the week [23]. The proportion increased at the end of intervention to 59% and 75%, respectively, while 1 year later, 58% of the usual care group and 62% of the program group maintained physical activity at that level [18].…”

Dietary influences on survival after ovarian cancer

“…However, the majority of studies that have examined vegetable and/or fruit intakes (or related micronutrients) have reported modest inverse associations 10. Two large multicenter intervention trials are currently under way to examine if diet modification can directly influence the risk for recurrence and survival after a diagnosis of breast cancer 24. The results of these trials will be available within the next 3–4 years.…”

Health behaviors during and after a cancer diagnosis

“…The WINS study is a multicenter, randomized, controlled trial investigating the effects of reducing dietary fat intake with adjuvant systemic therapy on cancer recurrence rates in postmenopausal women with early stage, surgically treated breast cancer. 56 The primary aim of the WHELS trial is to evaluate the effects of a high-vegetable, low fat diet in reducing breast cancer recurrence and mortality. Participants (n ϭ 3088) were randomly assigned to an intensive diet intervention or comparison group and will be followed through 2006.…”