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. 2024 May 15;159(8):856–863. doi: 10.1001/jamasurg.2024.1169

Breast Cancer Risk After Bariatric Surgery and Influence of Insulin Levels

A Nonrandomized Controlled Trial

Felipe M Kristensson 1,2,✉, Johanna C Andersson-Assarsson 1, Markku Peltonen 3, Peter Jacobson 1, Sofie Ahlin 1,4, Per-Arne Svensson 1,5, Kajsa Sjöholm 1, Lena M S Carlsson 1, Magdalena Taube 1
PMCID: PMC11097101  PMID: 38748431

Key Points

Question

Is bariatric surgery associated with a reduced risk of breast cancer in women with obesity, and does baseline insulin level modify this association?

Findings

In this nonrandomized controlled trial including 2867 women with obesity and a median follow-up of 23.9 years, bariatric surgery was associated with lower incidence of breast cancer compared to usual obesity care. The association between bariatric surgery and reduced risk was greatest in women with high levels of insulin at baseline.

Meaning

Bariatric surgery may protect against development of breast cancer in women with obesity, and insulin levels may help predict treatment benefit.

This nonrandomized controlled trial evaluates the association between bariatric surgery and breast cancer incidence and whether this association varies by baseline insulin level.

Abstract

Importance

Obesity and insulin are risk factors for breast cancer, and retrospective studies suggest bariatric surgery reduces breast cancer risk in women. However, long-term prospective data on breast cancer risk after bariatric surgery and the role of baseline insulin levels are lacking.

Objective

To examine if bariatric surgery is associated with breast cancer incidence in women and if treatment benefit is modified by baseline insulin levels.

Design, Setting, and Participants

The Swedish Obese Subjects (SOS) study was a nonrandomized intervention trial designed to investigate the long-term effects of bariatric surgery on obesity-related mortality and morbidity. Study recruitment took place between 1987 and 2001, and median (IQR) follow-up time was 23.9 years (20.1-27.1) years. The study was conducted at 25 public surgical departments and 480 primary health care centers in Sweden and included 2867 women aged 37 to 60 years and with body mass index 38 or greater (calculated as weight in kilograms divided by height in meters squared).

Intervention

In the surgery group (n = 1420), 260 women underwent gastric banding, 970 vertical banded gastroplasty, and 190 gastric bypass. The remaining contemporaneously matched control individuals (n = 1447) received usual obesity care.

Main Outcome and Measures

Breast cancer, the main outcome of this secondary report, was not a predefined outcome in the SOS study. Breast cancer events were identified in the Swedish National Cancer Registry.

Results

The study population comprised 2867 women with a mean (SD) age of 48.0 (6.2) years. During follow-up, there were 154 breast cancer events, 66 in the surgery group and 88 in the usual care group, and a decreased risk of breast cancer was observed in the bariatric surgery group (hazard ratio [HR], 0.68; 95% CI, 0.49–0.94; P = .019; adjusted HR, 0.72; 95% CI, 0.52-1.01; P = .06). The surgical treatment benefit on breast cancer risk was greater in women with baseline insulin levels above the median 15.8 μIU/L (HR, 0.48; 95% CI, 0.31-0.74; P = .001; adjusted HR, 0.55; 95% CI, 0.35-0.86; P = .008) compared to those below (HR, 0.95; 95% CI, 0.59-1.53; P = .84; adjusted HR, 1.01; 95% CI, 0.61-1.66; P = .97; interaction P = .02).

Conclusions and Relevance

This prospective clinical trial indicated a reduced risk of breast cancer after bariatric surgery in women with obesity. The surgical treatment benefit was predominantly seen in women with hyperinsulinemia.

Trial Registration

ClinicalTrials.gov Identifier: NCT01479452

Introduction

Breast cancer is one of the most common forms of cancers in women and one of the leading causes of cancer-associated death.1 Obesity is a major risk factor for breast cancer2,3 and is also associated with worse disease outcomes.4,5 As obesity rates continue to rise globally, breast cancer incidence is expected to increase.6,7

Insulin is a recognized cellular growth factor, and insulin resistance and hyperinsulinemia have been suggested as mediators of the elevated cancer risk in people with obesity.8 Today, bariatric surgery is one of the most efficient methods for large and maintained weight loss in people with obesity,9,10 and it has been shown to reduce insulin levels.11 Results from previous studies, including the Swedish Obese Subjects (SOS) study, have shown that bariatric surgery is associated with reduced incidence of overall cancer in people with obesity.12,13,14 We have also shown that bariatric surgery is associated with a reduced risk of female-specific cancer in women with obesity, especially in those with high insulin levels at baseline.15 Retrospective observational studies indicate that bariatric surgery may reduce breast cancer incidence in both women with obesity who were premenopausal and those who were postmenopausal, but this remains to be verified.16,17 Furthermore, the biological mechanisms underlying the observed reduction of cancer risk in people undergoing bariatric surgery are currently not well understood and require further investigation.18 To this end, large prospective studies with detailed patient information and data from national registries are needed.19 The aim of this study was to investigate the association between bariatric surgery and breast cancer in women in the prospective SOS study and to explore whether treatment benefit is modified by baseline insulin levels.

Methods

Study Design and Patients

The SOS study was a prospective, matched, intervention trial comparing the outcomes of bariatric surgery with usual obesity care on obesity-related mortality and morbidity.20 The study enrolled 4047 participants with obesity recruited through campaigns in mass media and at 25 public surgical departments and 480 primary health care centers in Sweden between September 1, 1987, and January 31, 2001. Inclusion criteria were age 37 to 60 years and a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) 34 or greater for men and 38 or greater for women. Exclusion criteria were identical in the treatment groups and designed to exclude patients not suitable for surgery. Notably, participants in the usual care group were all eligible for bariatric surgery but opted not to have surgical treatment.21

The surgery group consisted of 2010 participants who chose surgery, and treatments included nonadjustable or adjustable gastric banding, vertical banded gastroplasty, and gastric bypass. A matched control group of 2037 participants was created using 18 variables where matching was performed on group level.22 The intervention study began on the day of surgery for both participants who were treated surgically and matched control individuals. Participants in the control group received usual obesity care at their primary health care centers and will hereby be referred to as the usual care group. A randomized design was not approved for ethical reasons because of a high postoperative mortality rate in the 1980s.23,24

All participants underwent a baseline examination approximately 4 weeks before the start of the intervention. Further clinical examinations were carried out after 0.5, 1, 2, 3, 4, 6, 8, 10, 15, and 20 years. Blood samples for biochemical examination were taken at matching and baseline examinations, and after 2, 10, 15, and 20 years. All biochemical analyses were performed at the Central Laboratory of Sahlgrenska University Hospital, Gothenburg, Sweden. Questionnaires were filled out at every clinical examination. Seven regional ethics review boards approved the SOS study protocol (Supplement 1), and informed consent (oral or written) was obtained from all participants. At study start, the ethical rules for informed consent differed from today and oral consent was more commonly accepted in clinical studies compared to today’s standards. This study is reported according to the Transparent Reporting of Evaluations With Nonrandomized Designs (TREND) reporting guideline.

The current report, a secondary analysis, includes women only. The surgery group consisted of 1420 women; 260 (18.3%) underwent nonadjustable or adjustable gastric banding, 970 (68.3%) underwent vertical banded gastroplasty, and 190 (13.4%) underwent gastric bypass. The usual care group consisted of 1447 women. A trial flow diagram of participant recruitment and inclusion is shown in Figure 1.

Figure 1. Swedish Obese Subjects (SOS) Study Inclusion.

Figure 1.

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Outcomes and Measures

Baseline characteristics were obtained from clinical examinations, questionnaires, and centralized blood chemistry. The homeostasis model assessment-estimated insulin resistance (HOMA-IR) was used to estimate insulin resistance. HOMA-IR is calculated by multiplying fasting plasma insulin concentration by fasting plasma glucose concentration, and dividing the result by a constant (22.5 for SI units and 405 for conventional units).25 Baseline alcohol intake was calculated from dietary questionnaires, as previously described.26 Smoking was defined as a positive answer to the question, “Do you smoke daily?” Postmenopausal state was defined as a negative answer to the question, “Do you still menstruate?” or time for surgical menopause. Breast cancer, the main outcome of this report, was not a predefined outcome in the SOS study. Breast cancer events were identified in the Swedish Cancer Registry using ICD7 International Classification of Diseases, Seventh Revision (ICD-7), code 170. The Swedish Cancer Registry has more than 95% coverage for all malignant tumors, 99% of which are morphologically verified.27 Information on death and emigration status were obtained by cross-checking the SOS database against the Swedish Population and Address Register. Register data was complete up to December 31, 2020, at the time of analysis.

Statistical Analysis

Baseline characteristics are presented as mean values and standard deviations or counts and percentages when applicable. Comparisons between treatment groups were done with t test for continuous variables and Fisher exact test for categorical variables.

To analyze the effect of bariatric surgery on breast cancer risk, time to breast cancer event after study inclusion was compared between treatment groups using Kaplan-Meier estimates and log-rank test. Cumulative incidence rates were calculated as 1 minus the Kaplan-Meier estimate. Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% CIs. Analyses were adjusted for baseline age, BMI, alcohol use, and smoking status. The proportional hazard assumption was evaluated by assessing the interaction between treatment and logarithm of time.

To analyze the effect of insulin and related metabolic variables on breast cancer risk, incidence rates were calculated in subgroups based on median levels of insulin, blood glucose, HOMA-IR, BMI, and alcohol use, as well as by smoking status. An interaction effect for bariatric surgery was evaluated with Cox proportional hazards model with an interaction term. All interaction analyses were based on continuous variables, except smoking status, which was treated as a categorical variable.

To account for undiagnosed breast cancer at baseline, a separate analysis was performed excluding women with breast cancer diagnosis during the first 3 years of the study. An additional sensitivity analysis was performed to account for menopausal state, where treatment effect was evaluated separately in premenopausal or postmenopausal groups at baseline.

A per-protocol approach was used in all analyses, meaning that all participants were included in their original study group until any bariatric surgery was performed in the usual care group, or surgery to restore normal anatomy was performed in the surgery group, after which they were censored from the analysis. Three participants were excluded from all analyses due to diagnosis of breast cancer before study inclusion. Observations in the time-to-event analyses were censored if the study participant emigrated from Sweden, withdrew their consent, altered their intervention, died before the end of follow-up for reasons other than breast cancer, or were alive at the end of follow-up, at the corresponding date.

All P values are 2-sided and P values of less than .05 were considered statistically significant if not stated otherwise. Statistical analyses were carried out using R version 4.2.1 (R Foundation) and Stata version 15.1 (StataCorp).

Results

Baseline Characteristics and Changes in BMI

The study population comprised 2867 women with a mean (SD) age of 48.0 (6.2) years. The Table shows baseline characteristics of the surgery (n = 1420) and usual care (n = 1447) groups. For the 2 groups, there was a statistically significant difference in 12 of 17 characteristics. A larger proportion of women in the usual care group was in menopausal state at baseline compared to the surgery group (529 of 1447 [36.6%] vs 433 of 1420 [30.5%]; P = .001, respectively). In the surgery group, mean changes in BMI were −10.4, −7.7, −7.5, and −7.8 after 2, 10, 15, and 20 years of follow-up, respectively. In the usual care group, mean BMI changes were small during follow-up.

Table. Baseline Characteristics of Women in the Swedish Obese Subjects Study.

Characteristic Mean (SD) P value
Surgery group (n = 1420) Usual care group (n = 1447)
Age, y 47.2 (6.0) 48.8 (6.3) <.001
BMI 42.8 (4.3) 40.7 (4.6) <.001
Blood glucose, mg/dL 92 (34) 86 (31) .001
S-insulin, μIU/L 19.9 (12.9) 16.4 (9.6) <.001
HOMA-IR, μIU/L × mmol/L 5.3 (5.2) 4.2 (3.5) <.001
S-cholesterol, mg/dL 224 (42) 216 (39) <.001
S-HDL-C, mg/dL 54 (12) 54 (12) .53
S-triglycerides, mg/dL 186 (106) 159 (80) <.001
Alcohol consumption, g/d 3.2 (4.5) 3.3 (5.1) .48
Daily smoking, No. (%) 366 (25.8) 284 (19.7) <.001
Diabetes at baseline, No. (%) 203 (14.4) 158 (10.9) .006
No. of children 2.3 (1.3) 2.1 (1.4) .01
Previous breast cancer, No. (%) 1 (0.1) 2 (0.1) .57
Postmenopausal, No. (%) 433 (30.5) 529 (36.6) .001
Hysterectomy, No. (%) 84 (5.9) 56 (3.9) .01
Oophorectomy, No. (%) 11 (0.8) 9 (0.6) .62
Hormone/anticonception, No. (%) 214 (15.1) 202 (14.0) .40
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Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); HOMA-IR, homeostatic model assessment for insulin resistance; HDL-C, high-density lipoprotein cholesterol.

SI conversion factors: To convert blood glucose to millimoles per liter, multiply by 0.0555; to convert insulin to picomoles per liter, multiply by 6.945; to convert total cholesterol and HDL-C to millimoles per liter, multiply by 0.0259; and to convert triglycerides to millimoles per liter, multiply by 0.0113.

Breast Cancer Incidence in Relation to Treatment

During a median (IQR) follow-up of 23.9 (20.1-27.1 years) years, 154 breast cancer events occurred, 66 in the surgery group and 88 in the usual care group (log-rank test: χ21 = 5.63; P = .02). There were no significant differences in BMI during follow-up in participants with and without breast cancer diagnosis within the treatment groups (eFigure 1 in Supplement 2). In an unadjusted analysis, bariatric surgery was associated with a reduced risk of breast cancer compared to usual care (HR, 0.68; 95% CI, 0.49-0.94; P = .02); however, the association was no longer significant after adjustment for age, BMI, alcohol, and smoking status (adjusted HR, 0.72; 95% CI, 0.52-1.01; P = .06) (Figure 2). There was no support for violation of the proportional hazard assumption (test of interaction between treatment and time, adjusted P = .16). When excluding breast cancer events that occurred during the first 3 years after study inclusion, the association remained significant also after adjustment (adjusted HR, 0.67; 95% CI, 0.47-0.95; P = .02) (eFigure 2 in Supplement 2). When stratifying according to menopausal status at baseline, breast cancer incidence was higher in the usual care group than in the surgery group also after adjustment (adjusted HR, 0.64; 95% CI, 0.42-0.99; P = .045) in women who were premenopausal but not in those who were postmenopausal (adjusted HR, 0.84; 95% CI, 0.49-1.45; P = .54) (eFigure 3 in Supplement 2).

Figure 2. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups.

Figure 2.

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Cumulative incidence function plots based on competing risk regression, hazard ratio (HR), and adjusted HR (aHR). Adjustments were made for baseline age, body mass index, alcohol intake, and if the patient currently smokes. The unadjusted HR was 0.68 (95% CI, 0.49-0.94; P = .02). The incidence rate in the usual care group was 88 events or 2.9 per 1000 patient-years (95% CI, 2.4-3.6). The incidence rate in the surgery group was 66 events or 2.0 per 1000 patient-years (95% CI, 1.6-2.6).

Breast Cancer Incidence in Relation to Treatment and Baseline Insulin

Figure 3 shows the cumulative incidence of breast cancer in the surgery and usual care groups stratified by median baseline insulin levels (15.8 μIU/L). Five participants were excluded from the analysis due to missing data on baseline insulin. The surgical treatment benefit on breast cancer risk was greater in women with baseline insulin levels above the median (log-rank test P = .001; HR, 0.48; 95% CI, 0.31-0.74; P = .001; adjusted HR, 0.55; 95% CI, 0.35-0.86; P = .008) compared to those below the median (log-rank test P = .84; HR, 0.95; 95% CI, 0.59-1.53; P = .84; adjusted HR, 1.01; 95% CI, 0.61-1.66; P = .97) (test of interaction between insulin and treatment: χ21 = 5.11; P = .02) (Figure 4). After exclusion of breast cancer events that occurred during the first 3 years after study inclusion, the strength of the association was virtually unaltered (eFigure 4 in Supplement 2). In addition to insulin, also HOMA-IR was significantly associated with surgical treatment with respect to breast cancer risk (χ21 = 4.82; interaction P value = .03), with greater relative treatment benefit in women with higher HOMA-IR (Figure 4). There were no interactions between the other risk factors and treatment.

Figure 3. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups Stratified by Median Baseline Insulin Levels.

Figure 3.

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In women with insulin levels below the baseline median, the incidence rate in the usual care group was 40 events or 2.2 per 1000 patient-years (95% CI, 1.6-3.0), and in the surgery group, 29 events or 2.2 per 1000 patient-years (95% CI, 1.5-3.1). In women with insulin levels above the baseline median, the incidence rate in the usual care group was 48 events or 4.0 per 1000 patient-years (95% CI, 3.0-5.3), and in the surgery group, 37 events or 2.0 per 1000 patient-years (95% CI, 1.4-2.7). The surgical treatment benefit for breast cancer risk was greater in women with baseline insulin levels above the median (unadjusted hazard ratio [HR], 0.48]; 95% CI, 0.31-0.74; P = .001) compared with those below the baseline median insulin level (HR, 0.95; 95% CI, 0.59-1.53; P = .84). Median insulin at baseline was 15.8 μIU/L. aHR indicates adjusted HR.

Figure 4. Interaction Between Risk Factors and Treatment for Cumulative Incidence of Breast Cancer in Women in the Swedish Obese Subjects Study.

Figure 4.

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Subgrouping was based on median values, except smoking status, which was grouped as active smoking or not. When testing for interaction, risk factors were treated as continuous variables, except smoking, which was treated as a categorical variable. BMI indicates body mass index (calculated as weight in kilograms divided by height in meters squared); HOMA-IR, homeostatic model assessment for insulin resistance; HR, hazard ratio. SI conversion factors: to convert glucose to millimoles per liter, multiply by 0.0555; to convert insulin to picomoles per liter, multiply by 6.945.

When excluding breast cancer events that occurred during the first 3 years after study inclusion, results remained similar in the interaction analysis with the exception of blood glucose (χ21 = 4.25; interaction P value 0.04) (eFigure 5 in Supplement 2).

Discussion

To our knowledge, this is the first prospective nonrandomized controlled trial indicating an association between bariatric surgery and reduced risk of breast cancer in women with obesity. Our results are in line with previous retrospective studies16 and, in agreement with our previous study on female-specific cancer,15 we also show that the association between bariatric surgery and reduced risk of breast cancer is primarily observed in women with higher insulin levels at baseline.

The biological mechanisms by which bariatric surgery may reduce breast cancer risk are unknown, but it has been suggested that weight loss counteracts several potential pathways by which obesity may induce cancer.28,29 Metabolic syndrome has been suggested to increase the risk of several cancers, including breast cancer. Possible mediators of the increased risk include enhanced inflammation and an increase in growth factors, such as insulin.30 Several observations support a role of insulin in the development or progression of breast cancer.31 Insulin stimulates cell mitosis and inhibit apoptosis,32 and overexpression of insulin receptors is common in breast cancer cells.33 Hyperinsulinemia has been linked to poorer outcomes in women with breast cancer.34 Furthermore, high levels of insulin are associated with reduced production of sex hormone–binding globulin and increased levels of bioactive estrogen, contributing to the development of breast cancer.31 Insulin is also a major regulator of glucose homeostasis, and the importance of glucose control with respect to cancer risk in patients with obesity was highlighted in our previous study showing a 60% decrease in risk of overall cancer following diabetes remission in patients with obesity and type 2 diabetes.14 In line with this, Aminian et al13 recently showed that bariatric surgery was associated with a reduced risk of obesity-associated cancers; interestingly, this benefit remained unchanged regardless of diabetes status. The results of the latter study might appear to partially conflict with our findings; however, they could also indicate that hyperinsulinemia and hyperglycemia represent distinct aspects of metabolic disease. Research has demonstrated that hyperinsulinemia can precede a diabetes diagnosis by several years and does not inevitably result in diabetes.35,36 Previous research has also suggested distinct effects of hyperinsulinemia and diabetes on cancer disease. In a study on cancer mortality, hyperinsulinemia was identified as an independent risk factor for mortality, separate from diabetes status.37 It has also been shown that women with obesity may develop a proinflammatory environment in white adipose tissue depots, including breast tissue, with both local and systemic effects.38 Notably, one of these local effects is the increased transcription of the CYP19 gene encoding aromatase which enhances estrogen production.38

With respect to estrogen, there is a strong association between estrogen levels and estrogen receptor–positive breast cancer risk in women who were postmenopausal.39,40 Women who were postmenopausal with obesity have higher levels of estrogen compared to women with normal weight.41,42 This is thought mainly to be caused by increased activity of the enzyme aromatase in adipose tissue.41 In women who were postmenopausal, it has been suggested that bariatric surgery reduces the amount of tissue that expresses aromatase, leading to reduced estrogen production and decreased risk of breast cancer.18 In women who are premenopausal, the data are more unclear with some studies showing lower levels of estrogen41 and a reduced risk of breast cancer in those with obesity.43 However, recent retrospective reports on bariatric surgery in women with obesity showed a reduced risk of both premenopausal and postmenopausal breast cancer, compared to women not undergoing surgery.16,17

To summarize, there are several different pathways by which bariatric surgery may reduce breast cancer risk in women with obesity, highlighting the need for further studies. We speculate that our findings are explained by both the decreased insulin levels after bariatric surgery44 as well as reduced estrogen levels due to weight loss.

Strengths and Limitations

A major strength of the SOS study is that it constitutes a large, well-defined, prospective, controlled trial of bariatric surgery with long follow-up time and access to comprehensive national registers enabling the tracing of diseases, such as cancer, over time. The study also has some limitations, such as the nonrandomized design. Despite the matching process, there was a statistically significant difference in 12 of 17 baseline variables. This may largely be explained by the fact that the mean waiting time from the matching health examination to surgery was 13 months, and during this time there was an increase in mean weight in the surgery group, and a minor mean weight loss in the usual care group. These weight changes in turn caused several variables to become significantly different between the study groups at baseline. Furthermore, the 18-variable matching process was done at the group level according to the principle of sequential treatment assignment,22 which may have led to suboptimal matches for some individual variables. The differences were in many cases small in absolute terms, although they became statistically significant due to the large sample size in the SOS study. Importantly, there is not a clear distribution of risk factors in favor of either group. In addition, to further alleviate baseline differences, all analyses were adjusted for risk factors associated with breast cancer. Also, our study includes older surgical methods that are no longer used. However, vertical banded gastroplasty, the most commonly used method in our study, results in weight loss similar to that after sleeve gastrectomy.23,45 Since the protective effect of bariatric surgery on cancer risk appears to be related to the degree of weight loss,13 our results are likely to also be valid for surgical methods used today. No information was available on estrogen levels or breast cancer subtype. Another limitation of this report is that breast cancer incidence was not a predefined outcome and the analyses in this report should therefore be regarded as exploratory.

Conclusions

This prospective clinical trial indicated a reduced risk of breast cancer after bariatric surgery in women with obesity. The surgical treatment benefit was predominantly seen in women with hyperinsulinemia, suggesting insulin may be used as a predictor of treatment effect.

Supplement 1.

Trial protocol

jamasurg-e241169-s001.pdf (5.3MB, pdf)
Supplement 2.

eFigure 1. Changes in BMI in SOS-participants with and without breast cancer diagnosis

eFigure 2. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups – Excluding breast cancer events within the first 3 years after inclusion

eFigure 3. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups – Stratified by menopausal state

eFigure 4. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups Stratified by Median Baseline Insulin Levels - Excluding breast cancer events within the first 3 years after inclusion

eFigure 5. Interaction between Risk Factors and Treatment for Cumulative Incidence of Breast Cancer in Women of the SOS study - Excluding breast cancer events within the first 3 years after inclusion

jamasurg-e241169-s002.pdf (225.2KB, pdf)
Supplement 3.

Data sharing statement

jamasurg-e241169-s003.pdf (15.5KB, pdf)

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplement 1.

Trial protocol

jamasurg-e241169-s001.pdf (5.3MB, pdf)
Supplement 2.

eFigure 1. Changes in BMI in SOS-participants with and without breast cancer diagnosis

eFigure 2. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups – Excluding breast cancer events within the first 3 years after inclusion

eFigure 3. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups – Stratified by menopausal state

eFigure 4. Cumulative Incidence of Breast Cancer in Women of the Bariatric Surgery and Usual Care Groups Stratified by Median Baseline Insulin Levels - Excluding breast cancer events within the first 3 years after inclusion

eFigure 5. Interaction between Risk Factors and Treatment for Cumulative Incidence of Breast Cancer in Women of the SOS study - Excluding breast cancer events within the first 3 years after inclusion

jamasurg-e241169-s002.pdf (225.2KB, pdf)
Supplement 3.

Data sharing statement

jamasurg-e241169-s003.pdf (15.5KB, pdf)

Articles from JAMA Surgery are provided here courtesy of American Medical Association

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