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No. Studies show no evidence that reducing dietary fat decreases a woman’s risk of developing postmenopausal breast cancer within the subsequent 14 years (strength of recommendation [SOR]: B, based on large heterogeneous prospective cohort studies and appropriate meta-analyses of these studies). Overall, evidence is insufficient to recommend for or against reduction in dietary fat to reduce risk of breast cancer for women, although recommendations for prudent fat intake may be justified on other grounds.
Losing weight is still a good strategy
Kathryn Kolasa, PhD, RD, LDN
East Carolina University, Greenville, NC
Women at risk for breast cancer—and cancer survivors—want to know about lifestyle changes that can reduce their risks for cancer or recurrence. There is growing evidence that obesity plays a role in cancer development and promotion.
A low-fat diet has been demonstrated as a successful strategy for weight loss. However, for most women, making these changes can be difficult without extensive instruction, support, and motivation. Limiting sweetened beverages, increasing consumption of fruits and vegetables, and limiting fat intake are 3 strategies women can use to achieve a healthy weight. If this turns out to reduce their risk of breast cancer, so much the better!
Evidence summary
Our Medline search retrieved 1114 English-language studies published from 1960 through October 2006. We limited this set to randomized controlled trials and cohort studies, leaving 212 articles. We then excluded articles that had small sample sizes, did not follow subjects for at least 5 years, did not include original data, included men, did not give prevalence or incidence rate of breast cancer in the subjects, or did not discuss diet assessment tools. Of the remaining articles, we selected the 11 best studies to include in the review.
Early studies evaluating national average dietary fat intake and breast cancer incidence rates showed an almost linear relationship between increased dietary fat and increased breast cancer incidence.1 However, increased fat intake occurs primarily in industrialized nations, providing multiple possible confounders for increased rates of breast cancer, such as pollutants and increased consumption of preservatives, pesticides, and other chemicals.
Case-control studies have shown some minimally increased risk related to dietary fat consumption, but there is concern about recall bias in these studies.2 Since the late 1970s, 7 large, well-designed prospective cohort studies have examined the possible relationship between dietary fat and breast cancer.1 The findings have been somewhat contradictory, with some studies showing statistically significant associations toward increased risk with higher fat intake.3-5
Since the late 1990s, several meta-analyses, a systematic review of these cohort studies, and the Women’s Health Initiative Randomized Controlled Diet Initiative have largely concluded that there is no difference in breast cancer incidence between women with a low-fat diet (<20% of total calories from fat) and women with average or high-fat diets (>40% total calories from fat).1,3,6,7
The meta-analysis performed by Boyd et al did find a statistically significant difference, with relative risks ranging from 1.11 for overall to 1.19 for high-saturated-fat diets.8 The upper limit of all confidence intervals was no higher than 1.35, however, suggesting a lack of clinical significance. The best-designed studies also evaluated dietary composition with regard to key types of fat (saturated, mono- and poly-unsaturated; animal vs vegetable vs marine) and found no significant differences based on type of fat consumed.1
Preliminary evidence indicates that lowering dietary fat consumption may help with secondary prevention of breast cancer, but no large studies have been performed to date.9 Recently, a nested study within the Women’s Intervention Nutrition Study did show that women with breast cancer who decreased their fat intake to a median of 33 g/day had a hazard ratio of 0.76 for relapse over 60 months (compared with controls who ate a median of 51 g/day).10
Recommendations from others
There are no evidence-based or specific recommendations for the primary prevention of postmenopausal breast cancer for women through dietary fat reduction. In particular, neither the American Academy of Family Physicians, American College of Surgeons, National Institutes of Health, American College of Obstetricians and Gynecologists, American College of Physicians, US Preventive Services Task Force, or the Centers for Disease Control and Prevention provide any guidelines on dietary fat restriction for primary prevention of postmenopausal breast cancer.
The American Heart Association does have guidelines for coronary artery disease prevention for women, which include a low-fat diet.11 The USPSTF has no specific guidelines regarding dietary fat consumption for the general population.
1. Willett WC. Diet and breast cancer. J Intern Med 2001;249:395-411.
2. Bingham SA, Luben R, Welch A, Wareham N, Khaw KT, Day N. Are imprecise methods obscuring a relation between fat and breast cancer?. Lancet 2003;362:212-214.
3. Mattisson I, Wirfalt E, Wallstrom P, Gullberg B, Olsson H, Berglund G. High fat and alcohol intakes are risk factors of postmenopausal breast cancer: a prospective study from the Malmo diet and cancer cohort. Int J Cancer 2004;110:589-597.
4. Sieri S, Krogh V, Muti P, et al. Fat and Protein Intake and subsequent Breast Cancer risk in Postmenopausal Women. Nutr Cancer 2004;42:10-17.
5. Velie E, Kulldorff M, Schairer C, Block G, Albanes D, Schatzkin A. Dietary fat, fat subtypes, and breast cancer in postmenopausal women: a prospective cohort study. J Natl Cancer Inst 2000;92:833-839.
6. Holmes MD, Hunter DJ, Colditz GA, et al. Association of dietary intake of fat and fatty acids with risk of breast cancer. JAMA 1999;281:914-920.
7. Low-Fat Dietary Pattern and risk of Breast Cancer, Colorectal Cancer, and Cardiovascular Disease: The Women’s Health Initiative randomized Controlled Dietary Modification Trial. Available at: www.whi.org/findings/dm/dm.php. Accessed on June 14, 2007.
8. Boyd NF, Stone J, Vogt KN, Connelly BS, Martin LJ, Minkin S. Dietary fat and breast cancer risk revisited: a meta-analysis of the published literature. Br J Cancer 2003;89:1672-1685.
9. Rock CL. Diet and breast cancer: can dietary factors influence survival? J Mammary Gland Biol Neoplasia 2003;8:119-132.
10. Rowan T, Chlebowski GL, Blackburn CA, et al. Dietary Fat Reduction and Breast Cancer Outcome: Interim Efficacy Results From the Women’s Intervention Nutrition Study. J Natl Cancer Inst 2006;98:1767-1776.
11. Mosca L, Appel LJ, Benjamin EJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women. Circulation 2004;109:672-693.
No. Studies show no evidence that reducing dietary fat decreases a woman’s risk of developing postmenopausal breast cancer within the subsequent 14 years (strength of recommendation [SOR]: B, based on large heterogeneous prospective cohort studies and appropriate meta-analyses of these studies). Overall, evidence is insufficient to recommend for or against reduction in dietary fat to reduce risk of breast cancer for women, although recommendations for prudent fat intake may be justified on other grounds.
Losing weight is still a good strategy
Kathryn Kolasa, PhD, RD, LDN
East Carolina University, Greenville, NC
Women at risk for breast cancer—and cancer survivors—want to know about lifestyle changes that can reduce their risks for cancer or recurrence. There is growing evidence that obesity plays a role in cancer development and promotion.
A low-fat diet has been demonstrated as a successful strategy for weight loss. However, for most women, making these changes can be difficult without extensive instruction, support, and motivation. Limiting sweetened beverages, increasing consumption of fruits and vegetables, and limiting fat intake are 3 strategies women can use to achieve a healthy weight. If this turns out to reduce their risk of breast cancer, so much the better!
Evidence summary
Our Medline search retrieved 1114 English-language studies published from 1960 through October 2006. We limited this set to randomized controlled trials and cohort studies, leaving 212 articles. We then excluded articles that had small sample sizes, did not follow subjects for at least 5 years, did not include original data, included men, did not give prevalence or incidence rate of breast cancer in the subjects, or did not discuss diet assessment tools. Of the remaining articles, we selected the 11 best studies to include in the review.
Early studies evaluating national average dietary fat intake and breast cancer incidence rates showed an almost linear relationship between increased dietary fat and increased breast cancer incidence.1 However, increased fat intake occurs primarily in industrialized nations, providing multiple possible confounders for increased rates of breast cancer, such as pollutants and increased consumption of preservatives, pesticides, and other chemicals.
Case-control studies have shown some minimally increased risk related to dietary fat consumption, but there is concern about recall bias in these studies.2 Since the late 1970s, 7 large, well-designed prospective cohort studies have examined the possible relationship between dietary fat and breast cancer.1 The findings have been somewhat contradictory, with some studies showing statistically significant associations toward increased risk with higher fat intake.3-5
Since the late 1990s, several meta-analyses, a systematic review of these cohort studies, and the Women’s Health Initiative Randomized Controlled Diet Initiative have largely concluded that there is no difference in breast cancer incidence between women with a low-fat diet (<20% of total calories from fat) and women with average or high-fat diets (>40% total calories from fat).1,3,6,7
The meta-analysis performed by Boyd et al did find a statistically significant difference, with relative risks ranging from 1.11 for overall to 1.19 for high-saturated-fat diets.8 The upper limit of all confidence intervals was no higher than 1.35, however, suggesting a lack of clinical significance. The best-designed studies also evaluated dietary composition with regard to key types of fat (saturated, mono- and poly-unsaturated; animal vs vegetable vs marine) and found no significant differences based on type of fat consumed.1
Preliminary evidence indicates that lowering dietary fat consumption may help with secondary prevention of breast cancer, but no large studies have been performed to date.9 Recently, a nested study within the Women’s Intervention Nutrition Study did show that women with breast cancer who decreased their fat intake to a median of 33 g/day had a hazard ratio of 0.76 for relapse over 60 months (compared with controls who ate a median of 51 g/day).10
Recommendations from others
There are no evidence-based or specific recommendations for the primary prevention of postmenopausal breast cancer for women through dietary fat reduction. In particular, neither the American Academy of Family Physicians, American College of Surgeons, National Institutes of Health, American College of Obstetricians and Gynecologists, American College of Physicians, US Preventive Services Task Force, or the Centers for Disease Control and Prevention provide any guidelines on dietary fat restriction for primary prevention of postmenopausal breast cancer.
The American Heart Association does have guidelines for coronary artery disease prevention for women, which include a low-fat diet.11 The USPSTF has no specific guidelines regarding dietary fat consumption for the general population.
No. Studies show no evidence that reducing dietary fat decreases a woman’s risk of developing postmenopausal breast cancer within the subsequent 14 years (strength of recommendation [SOR]: B, based on large heterogeneous prospective cohort studies and appropriate meta-analyses of these studies). Overall, evidence is insufficient to recommend for or against reduction in dietary fat to reduce risk of breast cancer for women, although recommendations for prudent fat intake may be justified on other grounds.
Losing weight is still a good strategy
Kathryn Kolasa, PhD, RD, LDN
East Carolina University, Greenville, NC
Women at risk for breast cancer—and cancer survivors—want to know about lifestyle changes that can reduce their risks for cancer or recurrence. There is growing evidence that obesity plays a role in cancer development and promotion.
A low-fat diet has been demonstrated as a successful strategy for weight loss. However, for most women, making these changes can be difficult without extensive instruction, support, and motivation. Limiting sweetened beverages, increasing consumption of fruits and vegetables, and limiting fat intake are 3 strategies women can use to achieve a healthy weight. If this turns out to reduce their risk of breast cancer, so much the better!
Evidence summary
Our Medline search retrieved 1114 English-language studies published from 1960 through October 2006. We limited this set to randomized controlled trials and cohort studies, leaving 212 articles. We then excluded articles that had small sample sizes, did not follow subjects for at least 5 years, did not include original data, included men, did not give prevalence or incidence rate of breast cancer in the subjects, or did not discuss diet assessment tools. Of the remaining articles, we selected the 11 best studies to include in the review.
Early studies evaluating national average dietary fat intake and breast cancer incidence rates showed an almost linear relationship between increased dietary fat and increased breast cancer incidence.1 However, increased fat intake occurs primarily in industrialized nations, providing multiple possible confounders for increased rates of breast cancer, such as pollutants and increased consumption of preservatives, pesticides, and other chemicals.
Case-control studies have shown some minimally increased risk related to dietary fat consumption, but there is concern about recall bias in these studies.2 Since the late 1970s, 7 large, well-designed prospective cohort studies have examined the possible relationship between dietary fat and breast cancer.1 The findings have been somewhat contradictory, with some studies showing statistically significant associations toward increased risk with higher fat intake.3-5
Since the late 1990s, several meta-analyses, a systematic review of these cohort studies, and the Women’s Health Initiative Randomized Controlled Diet Initiative have largely concluded that there is no difference in breast cancer incidence between women with a low-fat diet (<20% of total calories from fat) and women with average or high-fat diets (>40% total calories from fat).1,3,6,7
The meta-analysis performed by Boyd et al did find a statistically significant difference, with relative risks ranging from 1.11 for overall to 1.19 for high-saturated-fat diets.8 The upper limit of all confidence intervals was no higher than 1.35, however, suggesting a lack of clinical significance. The best-designed studies also evaluated dietary composition with regard to key types of fat (saturated, mono- and poly-unsaturated; animal vs vegetable vs marine) and found no significant differences based on type of fat consumed.1
Preliminary evidence indicates that lowering dietary fat consumption may help with secondary prevention of breast cancer, but no large studies have been performed to date.9 Recently, a nested study within the Women’s Intervention Nutrition Study did show that women with breast cancer who decreased their fat intake to a median of 33 g/day had a hazard ratio of 0.76 for relapse over 60 months (compared with controls who ate a median of 51 g/day).10
Recommendations from others
There are no evidence-based or specific recommendations for the primary prevention of postmenopausal breast cancer for women through dietary fat reduction. In particular, neither the American Academy of Family Physicians, American College of Surgeons, National Institutes of Health, American College of Obstetricians and Gynecologists, American College of Physicians, US Preventive Services Task Force, or the Centers for Disease Control and Prevention provide any guidelines on dietary fat restriction for primary prevention of postmenopausal breast cancer.
The American Heart Association does have guidelines for coronary artery disease prevention for women, which include a low-fat diet.11 The USPSTF has no specific guidelines regarding dietary fat consumption for the general population.
1. Willett WC. Diet and breast cancer. J Intern Med 2001;249:395-411.
2. Bingham SA, Luben R, Welch A, Wareham N, Khaw KT, Day N. Are imprecise methods obscuring a relation between fat and breast cancer?. Lancet 2003;362:212-214.
3. Mattisson I, Wirfalt E, Wallstrom P, Gullberg B, Olsson H, Berglund G. High fat and alcohol intakes are risk factors of postmenopausal breast cancer: a prospective study from the Malmo diet and cancer cohort. Int J Cancer 2004;110:589-597.
4. Sieri S, Krogh V, Muti P, et al. Fat and Protein Intake and subsequent Breast Cancer risk in Postmenopausal Women. Nutr Cancer 2004;42:10-17.
5. Velie E, Kulldorff M, Schairer C, Block G, Albanes D, Schatzkin A. Dietary fat, fat subtypes, and breast cancer in postmenopausal women: a prospective cohort study. J Natl Cancer Inst 2000;92:833-839.
6. Holmes MD, Hunter DJ, Colditz GA, et al. Association of dietary intake of fat and fatty acids with risk of breast cancer. JAMA 1999;281:914-920.
7. Low-Fat Dietary Pattern and risk of Breast Cancer, Colorectal Cancer, and Cardiovascular Disease: The Women’s Health Initiative randomized Controlled Dietary Modification Trial. Available at: www.whi.org/findings/dm/dm.php. Accessed on June 14, 2007.
8. Boyd NF, Stone J, Vogt KN, Connelly BS, Martin LJ, Minkin S. Dietary fat and breast cancer risk revisited: a meta-analysis of the published literature. Br J Cancer 2003;89:1672-1685.
9. Rock CL. Diet and breast cancer: can dietary factors influence survival? J Mammary Gland Biol Neoplasia 2003;8:119-132.
10. Rowan T, Chlebowski GL, Blackburn CA, et al. Dietary Fat Reduction and Breast Cancer Outcome: Interim Efficacy Results From the Women’s Intervention Nutrition Study. J Natl Cancer Inst 2006;98:1767-1776.
11. Mosca L, Appel LJ, Benjamin EJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women. Circulation 2004;109:672-693.
1. Willett WC. Diet and breast cancer. J Intern Med 2001;249:395-411.
2. Bingham SA, Luben R, Welch A, Wareham N, Khaw KT, Day N. Are imprecise methods obscuring a relation between fat and breast cancer?. Lancet 2003;362:212-214.
3. Mattisson I, Wirfalt E, Wallstrom P, Gullberg B, Olsson H, Berglund G. High fat and alcohol intakes are risk factors of postmenopausal breast cancer: a prospective study from the Malmo diet and cancer cohort. Int J Cancer 2004;110:589-597.
4. Sieri S, Krogh V, Muti P, et al. Fat and Protein Intake and subsequent Breast Cancer risk in Postmenopausal Women. Nutr Cancer 2004;42:10-17.
5. Velie E, Kulldorff M, Schairer C, Block G, Albanes D, Schatzkin A. Dietary fat, fat subtypes, and breast cancer in postmenopausal women: a prospective cohort study. J Natl Cancer Inst 2000;92:833-839.
6. Holmes MD, Hunter DJ, Colditz GA, et al. Association of dietary intake of fat and fatty acids with risk of breast cancer. JAMA 1999;281:914-920.
7. Low-Fat Dietary Pattern and risk of Breast Cancer, Colorectal Cancer, and Cardiovascular Disease: The Women’s Health Initiative randomized Controlled Dietary Modification Trial. Available at: www.whi.org/findings/dm/dm.php. Accessed on June 14, 2007.
8. Boyd NF, Stone J, Vogt KN, Connelly BS, Martin LJ, Minkin S. Dietary fat and breast cancer risk revisited: a meta-analysis of the published literature. Br J Cancer 2003;89:1672-1685.
9. Rock CL. Diet and breast cancer: can dietary factors influence survival? J Mammary Gland Biol Neoplasia 2003;8:119-132.
10. Rowan T, Chlebowski GL, Blackburn CA, et al. Dietary Fat Reduction and Breast Cancer Outcome: Interim Efficacy Results From the Women’s Intervention Nutrition Study. J Natl Cancer Inst 2006;98:1767-1776.
11. Mosca L, Appel LJ, Benjamin EJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women. Circulation 2004;109:672-693.
Evidence-based answers from the Family Physicians Inquiries Network