Research table: Body weight and breast cancer risk

This summary table contains detailed information about research studies. Summary tables are a useful way to look at the science behind many breast cancer guidelines and recommendations. However, to get the most out of the tables, it’s important to understand some key concepts. Learn how to read a research table.

Introduction: Body weight differs in the way it’s linked to breast cancer risk before and after menopause.

• Before menopause, being overweight or obese is linked to a modestly decreased risk of breast cancer.
• After menopause, being overweight or obese is linked to an increased risk of breast cancer.

Learn more about body weight and breast cancer risk.

Learn about body weight and breast cancer survival.

Learn about the strengths and weaknesses of different types of studies.

See how this risk factor compares with other risk factors for breast cancer.

Study selection criteria: Prospective cohort studies with at least 1,000 breast cancer cases and at least 5 years of follow-up, pooled analyses and meta-analyses. 

Table notes: In the studies below, researchers use a measure called body mass index (BMI) to estimate body fat. BMI takes into account height and weight. Calculate your BMI.

For people ages 20 and older, weight status categories are:

BMI	Body weight status
18.5 to 24.9	Normal
25.0 to 29.9	Overweight
30.0 and greater	Obese

Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.

Menopausal hormone therapy (MHT) is FDA-approved for the short-term relief of menopausal symptoms. Women who use MHT have an increased risk of breast cancer. This increased breast cancer risk related to MHT may make it difficult to see an increased risk related to body weight in study data. For this reason, many studies report findings by MHT use. MHT may also be called postmenopausal hormone therapy or hormone replacement therapy (HRT).

Learn more about MHT and breast cancer risk.

 

Study	Study Population (number of participants)	Follow-up (years)	Comparisons of Body Mass Index (BMI)	Relative Risk of Breast Cancer in Heavier Women Compared to Leaner Women, by Menopausal Status RR (95% CI)
				Before Menopause	After Menopause
Prospective cohort studies
Korean National Health Insurance System Cohort [1]	6,272,367 (57,626 cases)	6	25-29.9 vs. 18.5-22.9	0.95 (0.91-0.98)	1.28 (1.25-1.32)
			30 or more vs. 18.5-22.9	0.90 (0.82-0.98)	1.54 (1.47-1.62)
Breast Cancer Surveillance Consortium [2]	1,279,443 (18,576 cases)	8	25-29.9 vs. 18.5-24.9	For estrogen receptor-positive (ER-positive) tumors: 1.08 (1.03-1.14) For estrogen receptor-negative (ER-negative) tumors: 1.28 (1.14-1.44)	For ER-positive tumors: 1.28 (1.21-1.35)† For ER-negative tumors: 1.17 (1.06-1.30)†
			30-34.9 vs. 18.5-24.9	For estrogen receptor-positive (ER-positive) tumors: 1.15 (1.06-1.25) For estrogen receptor-negative (ER-negative) tumors: 1.48 (1.25-1.77)	For ER-positive tumors: 1.53 (1.41-1.66)† For ER-negative tumors: 1.38 (1.16-1.63)†
			30-34.9 vs. 18.5-24.9	For ER-positive tumors: 1.15 (1.06-1.25) For ER-negative tumors: 1.48 (1.25-1.77)	For ER-positive tumors: 1.53 (1.41-1.66)† For ER-negative tumors: 1.38 (1.16-1.63)†
Akinyemiju et al. [3]	189,742 (12,698 cases)	16-17	24.9-30 vs. 18.5-25		1.08 (1.05-1.10)‡
Tretli et al. [4]	567,333 (8,427 cases)	18	Very small differences in BMI	0.84 (0.74-0.95)	1.16 (1.09-1.23)
Million Women Study (UK) [5]	1,222,630 (6,808 cases)	5	30 or more vs. Less than 23	0.79 (0.68-0.92)	1.29 (1.22-1.36)
Women’s Health Initiative – Observational Study [6]	63,330 (4,562 cases)	19	25-29.9 vs. Less than 25		1.21 (1.12-1.32)
			30-34.9 vs. Less than 25		1.41 (1.28-1.55)
			35 or more vs. Less than 25		1.69 (1.52-1.89)
Korean Cancer Prevention Study [7]	443,273 (3,973 cases)	11	25-29.9 vs. 23-24.9		1.18 (1.04-1.34)§
			30 or more vs. 23-24.9		1.13 (0.84-1.53)§
California Teachers Study [8]	109,862 (3,844 cases)	13-14	25 or more vs. Less than 25	0.94 (0.71-1.24)||	1.21 (1.07-1.37)||,¶
Urbute et al. [9]	443,887 (3,032 cases)**	3-17	25-29.9 vs. 18.5-24.9	0.90 (0.82-0.98)††
			30 or more vs. 18.5-24.9	0.77 (0.68-0.87)††
Multiethnic Cohort Study [10]	82,971 (3,080 cases)	8-11	25-29.9 vs. 20-24.9		1.35 (1.17-1.57)‡‡
			30 or more vs. 20-24.9		1.60 (1.36-1.87)‡‡
UK Biobank [11]	162,691 (2,913 cases)	6	27-29.9 vs. 15-24		1.32 (1.18-1.47)
			30 or more vs. 15-24		1.52 (1.36-1.70)
Nurses’ Health Study [12]	95,256 (2,517 cases)	16	More than 31 vs. 20 or less	0.62 (0.45-0.86)	1.59 (1.09-2.32)¶
PLCO Cancer Screening Trial [13]	70,575 (2,063 cases)	5	25-29.9 vs. 18.5-24.9		1.06 (0.95-1.17)
			30-34.9 vs. 18.5-24.9		1.10 (0.97-1.26)
			35 or more vs. 18.5-24.9		1.21 (1.02-1.43)
Canadian National Breast Screening Study [14]	40,318 (1,673 cases)	16	30 or more vs. Less than 25	1.01 (0.74-1.37)	1.26 (0.95-1.67)
Lundqvist et al. [15]	36,490 (1,637 cases)	26	30 or more vs. 18.5-25	0.8 (0.4-1.3)	1.3 (1.0-1.7)
E3N Women’s Cohort Study—France [16]	94,805 (1,522 cases)	10	30 or more vs. 18.5-25	0.66 (0.40-1.10)	1.17 (0.89-1.57)¶
Tornberg et al. [17]	47,003 (1,466 cases)	25	28 or more vs. Less than 22	0.41Sig	1.13Sig
Nurses’ Health Study II [18]	113,130 (1,398 cases)	14	30 or more vs. Less than 20	0.81 (0.68-0.96)
Swedish Mammography Screening Cohort [19]	51,823 (1,188 cases)	8	30 or more vs. 18.5-24.9		1.38 (1.07-1.77)¶
Shanghai Women’s Health Study [20]	68,253 (1,162 cases)	15	30 or more vs. 18.5-22.9	0.98 (0.62-1.57)	2.43 (1.73-3.40)
PROCRAS Study (UK) [21]	47,042 (1,142 cases)	6	23-24.9 vs. 18.5-22.4	1.03 (0.70-1.52)	1.56 (1.17-2.09)
			25-29.9 vs. 18.5-22.4	1.16 (0.80-1.68)	1.88 (0.80-1.68)
			30 or more vs. 18.5-22.4	1.41 (0.92-2.16)	2.38 (1.77-3.20)
Kangbuk Samsung Cohort Study (Korea) [22]	125,188 (1,110 cases)	7	23 or more vs. Less than 19.5	0.80 (0.67-0.96)
Cancer Prevention Study-II (CPS-II) [23]	28,965 (1,088 cases)	12	25-29.9 vs. Less than 25		1.26 (1.07-1.48)
			30 or more vs. Less than 25		1.40 (1.10-1.78)
Black Women’s Health Study [24]	52,080 (1,062 cases)	10	35 or more vs. Less than 25	1.35 (0.53-3.47)	0.78 (0.58-1.05)
Vorarlberg Health Monitoring and Promotion Program-Austria [25]	78,484 (1,045 cases)	10	35 or more vs. 18.5-24.9		1.01 (0.72-1.42)§§
Pooled and meta-analyses
World Cancer Research Fund International [26]	32 studies (15,307 cases)		25-29.9 vs. 18.5-24.9	0.93 (0.87-0.98)
			30 or more vs. 18.5-24.9	0.82 (0.72-0.93)
	42 studies (73,346 cases)		25-29.9 vs. 18.5-24.9		1.16 (1.10-1.22)
			30 or more vs. 18.5-24.9		1.29 (1.19-1.39)
van den Brandt et al. [27]	1,061,915 (36,297 cases)		27-29.9 vs. Less than 21	0.89 (0.79-1.01)	1.58 (1.46-1.72)||||
			30 or more vs. Less than 21	0.78 (0.64-0.93)	1.61 (1.45-1.79)||||
Research Group for the Development and Evaluation of Cancer Prevention Strategies in Japan [28]	183,940 (1,783 cases, studies of Japanese women only)		30 or more vs. 23-24.9	1.80 (0.81-3.99)	1.26 (0.92-1.72)
Chen et al. [29]	18 studies		Highest BMI vs. Lowest BMI	0.94 (0.81-1.11)
	26 studies		Highest BMI vs.  Lowest BMI		1.33 (1.20-1.48)
Dehesh et al. [30]	18 cohort studies		30 or more vs. 18.5-24.9		1.29 (1.16-1.43)
	11 cohort studies		30 or more vs. 18.5-24.9	0.88 (0.81-0.96)
Suzuki et al. [31]	4 studies		Highest BMI vs. Average BMI		For hormone receptor-positive tumors: 1.74 (1.34-2.25) For hormone receptor-negative tumors: 0.90 (0.53-1.52)

Sig = Results were statistically significant.

† Relative risk for women not currently using MHT (estrogen plus progestin). Among MHT users, those with a higher BMI had an increased risk of estrogen receptor-positive breast cancer, but not estrogen receptor-negative breast cancer.

‡ Relative risk for all postmenopausal women. Among African American women, relative risk was 1.05 (0.94-1.17) and among white women, relative risk was 1.07 (1.04-1.09).

§ Includes premenopausal and postmenopausal women.

|| All breast cancers were estrogen receptor-positive.

¶ Relative risk for women who never used MHT. Among MHT users, there was no increase in breast cancer risk.

** All women in the study had given birth.

†† When findings were examined by estrogen receptor status, women who were overweight or obese had a decreased risk of estrogen receptor-positive premenopausal breast cancer. Being overweight or obese was not linked to the risk of estrogen receptor-negative premenopausal breast cancer.

‡‡ Relative risk for women who never used MHT. Relative risks among former MHT users were similar. Among current MHT users, there was no increase in breast cancer risk.

§§ Combined premenopausal and postmenopausal breast cancer risk. For women 65 and older, the relative risk for BMI 30-34.9 vs. 18.5-24.9 was 1.48 (1.12-1.95).

|||| Relative risk for women who never used MHT. Relative risks among ever MHT users also showed an increased risk of breast cancer.

References

1. Park JW, Han K, Shin DW, et al. Obesity and breast cancer risk for pre- and postmenopausal women among over 6 million Korean women. Breast Cancer Res Treat. 185(2):495-506, 2021.
2. Kerlikowske K, Gard CC, Tice JA, et al. for the Breast Cancer Surveillance Consortium. Risk factors that increase risk of estrogen receptor-positive and -negative breast cancer. J Natl Cancer Inst. 109(5):djw276, 2017.
3. Akinyemiju T, Wiener H, Pisu M. Cancer-related risk factors and incidence of major cancers by race, gender and region; analysis of the NIH-AARP diet and health study. BMC Cancer. 17(1):597, 2017. 
4. Tretli S. Height and weight in relation to breast cancer morbidity and mortality. A prospective study of 570,000 women in Norway. Int J Cancer. 44:23-30, 1989.
5. Reeves GK, Pirie K, Beral V, Green J, Spencer E, Bull D. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ. 335(7630):1134, 2007.
6. Chlebowski RT, Aragaki AK, Pan K, et al. Breast cancer incidence and mortality by metabolic syndrome and obesity: the Women’s Health Initiative. Cancer. 2024 May 13 [Online ahead of print].
7. Jee SH, Yun JE, Park EJ, et al. Body mass index and cancer risk in Korean men and women. Int J Cancer. 123(8):1892-6, 2008.
8. Horn-Ross PL, Canchola AJ, Bernstein L, Neuhausen SL, Nelson DO, Reynolds P. Lifetime body size and estrogen-receptor-positive breast cancer risk in the California Teachers Study cohort. Breast Cancer Res. 18(1):132, 2016.
9. Urbute A, Frederiksen K, Kjaer SK. Early adulthood overweight and obesity and risk of premenopausal ovarian cancer, and premenopausal breast cancer including receptor status: prospective cohort study of nearly 500,000 Danish women. Ann Epidemiol. 70:61-67, 2022.
10. White KK, Park SY, Kolonel LN, Henderson BE, Wilkens LR. Body size and breast cancer risk: The multiethnic cohort. Int J Cancer. 131(5):E705-16, 2012.
11. Guo W, Key TJ, Reeves GK. Adiposity and breast cancer risk in postmenopausal women: results from the UK Biobank prospective cohort. Int J Cancer. 143(5):1037-1046, 2018.
12. Huang Z, Hankinson SE, Colditz GA, et al. Dual effects of weight and weight gain on breast cancer risk. JAMA. 278(17):1407-1411, 1997.
13. Lacey JV Jr, Kreimer AR, Buys SS, et al. for the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial Project Team. Breast cancer epidemiology according to recognized breast cancer risk factors in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial Cohort. BMC Cancer. 9:84, 2009.
14. Silvera SAN, Jain M, Howe GR, et al. Energy balance and breast cancer risk: a prospective cohort study. Breast Cancer Res Treat. 97(1):97-106, 2006.
15. Lundqvist E, Kaprio J, Verkasalo PK, et al. Co-twin control and cohort analyses of body mass index and height in relation to breast, prostate, ovarian, corpus uteri, colon and rectal cancer among Swedish and Finnish twins. Int J Cancer. 121(4):810-8, 2007.
16. Tehard B, Lahmann PH, Riboli E, Clavel-Chapelon F. Anthropometry, breast cancer and menopausal status: Use of repeated measurements over 10 years of follow-up-results of the French E3N women’s cohort study. Int J Cancer. 111(2):264-9, 2004.
17. Tornberg SA and Carstensen JM. Relationship between Quetelet’s Index and cancer of breast and female genital tract in 47,000 women followed for 25 years. Br J Cancer. 69:358-361, 1994.
18. Michels K, Terry KL, Willett WC. Longitudinal study on the role of body size in premenopausal breast cancer. Arch Intern Med. 166(21):2395-402, 2006.
19. Suzuki R, Rylander-Rudqvist T, Ye W, et al. Body weight and postmenopausal breast cancer risk defined by estrogen and progesterone receptor status among Swedish women: A prospective cohort study. Int J Cancer. 119(7):1683-9, 2006.
20. Liu Y, Warren Andersen S, Wen W, et al. Prospective cohort study of general and central obesity, weight change trajectory, and risk of major cancers among Chinese women. Int J Cancer. 139(7):1461-70, 2016.
21. Renehan AG, Pegington M, Harvie MN, et al. Young adulthood body mass index, adult weight gain and breast cancer risk: the PROCAS Study (United Kingdom). Br J Cancer. 122(10):1552-1561, 2020.
22. Tran TXM, Chang Y, Choi HR, et al. Adiposity, body composition measures, and breast cancer risk in Korean premenopausal women. JAMA Netw Open. 7(4):e245423. 2024.
23. Gaudet MM, Carter BD, Patel AV, Teras LR, Jacobs EJ, Gapstur SM. Waist circumference, body mass index, and postmenopausal breast cancer incidence in the Cancer Prevention Study-II Nutrition Cohort. Cancer Causes Control. 25(6):737-45, 2014.
24. Palmer JR, Adams-Campbell LL, Boggs DA, Wise LA, Rosenberg L. A prospective study of body size and breast cancer in black women. Cancer Epidemiol Biomarkers Prev. 16(9):1795-802, 2007.
25. Rapp K, Schroeder J, Klenk J, et al. Obesity and incidence of cancer: a large cohort study of over 145,000 adults in Austria. Br J Cancer. 93(9):1062-7, 2005.
26. Chan DSM, Abar L, Cariolou M, et al. World Cancer Research Fund International: Continuous Update Project-systematic literature review and meta-analysis of observational cohort studies on physical activity, sedentary behavior, adiposity, and weight change and breast cancer risk. Cancer Causes Control. 30(11):1183-1200, 2019.
27. van den Brandt PA, Ziegler RG, Wang M, et al. Body size and weight change over adulthood and risk of breast cancer by menopausal and hormone receptor status: a pooled analysis of 20 prospective cohort studies. Eur J Epidemiol. 36(1):37-55, 2021.
28. Wada K, Nagata C, Tamakoshi A, et al. for the Research Group for the Development and Evaluation of Cancer Prevention Strategies in Japan. Body mass index and breast cancer risk in Japan: a pooled analysis of eight population-based cohort studies. Ann Oncol. 25(2):519-24, 2014.
29. Chen Y, Liu L, Zhou Q, et al. Body mass index had different effects on premenopausal and postmenopausal breast cancer risks: a dose-response meta-analysis with 3,318,796 subjects from 31 cohort studies. BMC Public Health. 17(1):936, 2017.
30. Dehesh T, Fadaghi S, Seyedi M, et al. The relation between obesity and breast cancer risk in women by considering menstruation status and geographical variations: a systematic review and meta-analysis. BMC Womens Health. 23(1):392, 2023.
31. Suzuki R, Orsini N, Saji S, Key TJ, Wolk A. Body weight and incidence of breast cancer defined by estrogen and progesterone receptor status–a meta-analysis. Int J Cancer. 124(3):698-712, 2009. 

 

* Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date.