Body size, body composition and endometrial cancer risk among postmenopausal women in UK Biobank

Adiposity and risks of gastrointestinal cancers: A 10-year prospective study of 0.5 million Chinese adults

Associations of adiposity with risks of oesophageal squamous cell carcinoma (ESCC) and non-cardia stomach cancer, both prevalent in China, are still inconclusive. While adiposity is an established risk factor for colorectal cancer, the relevance of fat-free mass and early-adulthood adiposity remains to be explored. The prospective China Kadoorie Biobank study included 0.5 million adults (aged 30-79 years) from 10 areas in China. Participants' body size and composition were measured at baseline and at resurveys (amongst a subset). After >10 years of follow-up, 2350, 3345 and 3059 incident cases of oesophageal (EC), stomach (SC) and colorectal (CRC) cancers were recorded, respectively. Cox regression was used to estimate hazard ratios (HRs) for these cancers in relation to different adiposity traits. General and central adiposity were inversely associated with EC (primarily ESCC) risk, with HRs of 0.81 (95% CI 0.77-0.85), 0.76 (0.72-0.81) and 0.87 (0.83-0.92) per SD increase in usual levels of BMI, body fat percentage (BF%) and waist circumference (WC), respectively. Adiposity was also inversely associated with SC risk [HR = 0.79 (0.75-0.83) and 0.88 (0.84-0.92) per SD increase in usual BF% and WC], with heterogeneity by cardia and non-cardia subsites, and positively associated with CRC [HR = 1.09 (1.03-1.15) and 1.17 (1.12-1.22) per SD higher usual BF% and WC]. Fat-free mass was inversely associated with EC [HR = 0.93 (0.89-0.98) per SD increase] but positively associated with CRC [1.09 (1.04-1.14)], while BMI at age 25 was positively associated with all three cancers. After mutual adjustment, general adiposity remained inversely associated with EC and SC, while central adiposity remained positively associated with CRC.

Different Patterns of the Relationship Between Gynecological Malignancy and Obesity Index: A Nationwide Retrospective Cohort Study in Korea

BACKGROUND

In Korea, the patterns of prevalence of gynecological cancers have shifted due to rising obesity-related cancer cases. We evaluated the associations of body mass index (BMI) and waist circumference (WC) with the risk of gynecological malignancy in Korean women.

METHODS

Using National Health Insurance Service cohort data, we analyzed 365,581 participants among the 1,999,980 women aged ≥ 19 years who underwent health check-ups at the baseline year 2009-2010, excluding those who died, those with prior cancer diagnoses, underwent hysterectomy and/or salpingo-oophorectomy before the index date (January 1st, 2011), or missing/outliers BMI and WC values. Follow-up extended to December 31st, 2021, evaluating the incidences of endometrial, ovarian, and cervical cancer. The hazard ratios (HRs) and 95% confidence intervals (CIs) for each gynecological malignancy according to BMI and WC were calculated using Cox proportional hazard regression.

RESULTS

Among the 365,581 participants, 898, 1,268, and 873 cases of endometrial, ovarian, and cervical cancer occurred, respectively. HRs (95% CIs) for endometrial cancer were 1.37 (1.15-1.63), 1.63 (1.38-1.94), and 3.64 (2.81-4.70) for BMIs of 23.0-24.9, 25.0-29.9, and ≥ 30 kg/m² compared to BMI of 18.5-22.9 kg/m² (P for trend < 0.001). HRs (95% CIs) for ovarian cancer were 1.16 (1.00-1.33), 1.19 (1.03-1.37), and 1.49 (1.12-1.98) for BMIs of 23.0-24.9, 25.0-29.9, and ≥ 30 kg/m² compared to BMI of 18.5-22.9 kg/m² (P for trend = 0.002). No significant association was found between BMI and the risk for cervical cancer (P for trend = 0.266). HRs (95% CIs) for endometrial cancer were 1.35 (1.09-1.66), 1.41 (1.14-1.74), and 1.90 (1.55-2.34) for the 2nd, 3rd, and 4th quartiles of WCs compared to the 1st quartile (P for trend <0.001). Ovarian cancer tended to increase and cervical cancer tended to decrease as WC increased (P for trend = 0.035 for ovarian cancer, P for trend = 0.034 for cervical cancer).

CONCLUSION

In Korean women, the risks of endometrial and ovarian cancers increased significantly from the pre-obese level as BMI and WC increased, while cervical cancer risk tended to increase as WC decreased. Management of obesity should be reinforced for the prevention of obesity-related gynecological cancers, considering the increasing incidence of these cancers among Korean women.

Tumor immunology and immunotherapy for endometrial cancer

INTRODUCTION

Recent clinical trials show the efficacy of immune checkpoint inhibitors (ICIs) or a combination of ICI and poly (ADP-ribose) polymerase (PARP) inhibitors for advanced or recurrent endometrial cancer. However, the basis for such treatment effects remains unclear, hindering the advancement of personalized therapy.

AREAS COVERED

This review includes a detailed interpretation of subgroup analysis data from phase III clinical trials for endometrial cancer evaluating the efficacy of chemotherapy plus ICIs (NRG-GY018, RUBY, AtTEnd, KEYNOTE-B21) or chemotherapy plus ICI with/without olaparib (DUO-E). We focused on the relationship between obesity, the effect of PARP inhibitors, and tumor immunity in endometrial cancer, searched for relevant literature published from 2000 to 2024 in PubMed, and conducted a narrative review.

EXPERT OPINION

Chemotherapy plus ICI is appropriate for dMMR. Chemotherapy plus ICI and PARP inhibitor may be appropriate for TP53abn type or serous carcinoma because PARP inhibitor enhances the efficacy of ICI by activating the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway. Obese patients may benefit more from ICIs, and this appears to cause the variation in efficacy between regions/countries. Administration for measurable disease appears important to increase the effect of ICIs. Diet and exercise may also be important factors.

Screening Strategies to Improve Early Diagnosis in Endometrial Cancer

Endometrial cancer is the most common gynecological malignancy in high-income countries and the sixth most common cancer in women. Overall incidence has risen in the last few decades as a consequence of the increase in the prevalence of its risk factors, mainly obesity and the aging of the population, and although diagnoses have increased across all age groups, the incidence rates have doubled in women under the age of 40 years. The survival rates of endometrial cancer are highly dependent on its stage at diagnosis, bringing to the fore the importance of early diagnosis. The aim of a screening strategy in this type of tumor should be to detect the disease in the pre-invasive or early stage (before developing myometrial invasion), which would improve cure rates, reduce the morbidity associated with aggressive treatment and offer uterus-sparing management options for younger women. The ideal screening tool in this scenario would be a minimally invasive, inexpensive and easy-to-perform test or auto-test, which could be implemented in a routine gynecologic checkup of patients at-risk or in the general adult population. In this comprehensive review, we aim to define the populations at higher risk of developing endometrial cancer, to assess the performance of current diagnostic tools when used in a screening setting and to discuss the accuracy of new molecular screening strategies.

Adiposity indicators exhibit depot- and sex-specific associations with multimorbidity onset: A cohort study of the UK Biobank

AIM

This study investigated the depot- and sex-specific associations of adiposity indicators with incident multimorbidity and comorbidity pairs.

MATERIALS AND METHODS

We selected 382 678 adults without multimorbidity (≥2 chronic diseases) at baseline from the UK Biobank. General obesity, abdominal obesity and body fat percentage indices were measured.

RESULTS

Cox proportional hazard regression analyses of general obesity indices revealed that for every one-unit increase in body mass index, the risk of incident multimorbidity increased by 5.2% (95% confidence interval 5.0%-5.4%). A dose-response relationship was observed between general obesity degrees and incident multimorbidity. The analysis of abdominal obesity indices showed that for every 0.1 increment in waist-to-height ratio and waist-to-hip ratio, the risk of incident multimorbidity increased by 42.0% (37.9%-46.2%) and 27.9% (25.7%-30.0%), respectively. Central obesity, as defined by waist circumference, contributed to a 23.2% increased risk of incident multimorbidity. Hip circumference and hip-to-height ratio had protective effects on multimorbidity onset. Consistent findings were observed for males and females. Body fat percentage elevated 3% (0.2%-5.9%) and 5.3% (1.1%-9.7%) risks of incident multimorbidity in all adults and females, respectively. Arm fat percentages elevated 5.3% (0.8%-9.9%) and 19.4% (11.0%-28.5%) risks of incident multimorbidity in all adults and males, respectively. The general obesity indices, waist circumference, waist-to-height ratio, waist-to-hip ratio and central obesity increased the onset of comorbidity pairs, whereas hip circumference and hip-to-height ratio decreased the onset of comorbidity pairs. These adiposity indicators mainly affect diabetes mellitus-related comorbidity onset in males and hypertensive-related comorbidity onset in females.

CONCLUSIONS

Adiposity indicators are predictors of multimorbidity and comorbidity pairs and represent a promising approach for intervention.

Metabolic syndrome score as an indicator in a predictive nomogram for lymph node metastasis in endometrial cancer

BACKGROUND

Lymph node metastasis (LNM) is an important factor affecting endometrial cancer (EC) prognosis. Current controversy exists as to how to accurately assess the risk of lymphatic metastasis. Metabolic syndrome has been considered a risk factor for endometrial cancer, yet its effect on LNM remains elusive. We developed a nomogram integrating metabolic syndrome indicators with other crucial variables to predict lymph node metastasis in endometrial cancer.

METHODS

This study is based on patients diagnosed with EC in Peking University People's Hospital between January 2004 and December 2020. A total of 1076 patients diagnosed with EC and who underwent staging surgery were divided into training and validation cohorts according to the ratio of 2:1. Univariate and multivariate logistic regression analyses were used to determine the significant predictive factors.

RESULTS

The prediction nomogram included MSR, positive peritoneal cytology, lymph vascular space invasion, endometrioid histological type, tumor size >  = 2 cm, myometrial invasion >  = 50%, cervical stromal invasion, and tumor grade. In the training group, the area under the curve (AUC) of the nomogram and Mayo criteria were 0.85 (95% CI: 0.81-0.90) and 0.77 (95% CI: 0.77-0.83), respectively (P < 0.01). In the validation group (N = 359), the AUC was 0.87 (95% CI: 0.82-0.93) and 0.80 (95% CI: 0.74-0.87) for the nomogram and the Mayo criteria, respectively (P = 0.01). Calibration plots revealed the satisfactory performance of the nomogram. Decision curve analysis showed a positive net benefit of this nomogram, which indicated clinical value.

CONCLUSION

This model may promote risk stratification and individualized treatment, thus improving the prognosis.

Metabolic risk score as a predictor in a nomogram for assessing myometrial invasion for endometrial cancer

The purpose of the present study was to investigate the predictive value of metabolic syndrome in evaluating myometrial invasion (MI) in patients with endometrial cancer (EC). The study retrospectively included patients with EC who were diagnosed between January 2006 and December 2020 at the Department of Gynecology of Nanjing First Hospital (Nanjing, China). The metabolic risk score (MRS) was calculated using multiple metabolic indicators. Univariate and multivariate logistic regression analyses were performed to determine significant predictive factors for MI. A nomogram was then constructed based on the independent risk factors identified. A calibration curve, a receiver operating characteristic (ROC) curve and decision curve analysis (DCA) were used to evaluate the effectiveness of the nomogram. A total of 549 patients were randomly assigned to a training or validation cohort, with a 2:1 ratio. Data was then gathered on significant predictors of MI in the training cohort, including MRS [odds ratio (OR), 1.06; 95% confidence interval (CI), 1.01-1.11; P=0.023], histological type (OR, 1.98; 95% CI, 1.11-3.53; P=0.023), lymph node metastasis (OR, 3.15; 95% CI, 1.61-6.15; P<0.001) and tumor grade (grade 2: OR, 1.71; 95% CI, 1.23-2.39; P=0.002; Grade 3: OR, 2.10; 95% CI, 1.53-2.88; P<0.001). Multivariate analysis indicated that MRS was an independent risk factor for MI in both cohorts. A nomogram was generated to predict a patient's probability of MI based on the four independent risk factors. ROC curve analysis showed that, compared with the clinical model (model 1), the combined model with MRS (model 2) significantly improved the diagnostic accuracy of MI in patients with EC (area under the curve in model 1 vs. model 2: 0.737 vs. 0.828 in the training cohort and 0.713 vs. 0.759 in the validation cohort). Calibration plots showed that the training and validation cohorts were well calibrated. DCA showed that a net benefit is obtained from the application of the nomogram. Overall, the present study developed and validated a MRS-based nomogram predicting MI in patients with EC preoperatively. The establishment of this model may promote the use of precision medicine and targeted therapy in EC and has the potential to improve the prognosis of patients affected by EC.

Metabolically Defined Body Size Phenotypes and Risk of Endometrial Cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)

BACKGROUND

Obesity is a risk factor for endometrial cancer but whether metabolic dysfunction is associated with endometrial cancer independent of body size is not known.

METHODS

The association of metabolically defined body size phenotypes with endometrial cancer risk was investigated in a nested case-control study (817 cases/ 817 controls) within the European Prospective Investigation into Cancer and Nutrition (EPIC). Concentrations of C-peptide were used to define metabolically healthy (MH; <1st tertile) and metabolically unhealthy (MU; ≥1st tertile) status among the control participants. These metabolic health definitions were combined with normal weight (NW); body mass index (BMI)<25 kg/m2 or waist circumference (WC)<80 cm or waist-to-hip ratio (WHR)<0.8) and overweight (OW; BMI≥25 kg/m2 or WC≥80 cm or WHR≥0.8) status, generating four phenotype groups for each anthropometric measure: (i) MH/NW, (ii) MH/OW, (iii) MU/NW, and (iv) MU/OW.

RESULTS

In a multivariable-adjusted conditional logistic regression model, compared with MH/NW individuals, endometrial cancer risk was higher among those classified as MU/NW [ORWC, 1.48; 95% confidence interval (CI), 1.05-2.10 and ORWHR, 1.68; 95% CI, 1.21-2.35] and MU/OW (ORBMI, 2.38; 95% CI, 1.73-3.27; ORWC, 2.69; 95% CI, 1.92-3.77 and ORWHR, 1.83; 95% CI, 1.32-2.54). MH/OW individuals were also at increased endometrial cancer risk compared with MH/NW individuals (ORWC, 1.94; 95% CI, 1.24-3.04).

CONCLUSIONS

Women with metabolic dysfunction appear to have higher risk of endometrial cancer regardless of their body size. However, OW status raises endometrial cancer risk even among women with lower insulin levels, suggesting that obesity-related pathways are relevant for the development of this cancer beyond insulin.

IMPACT

Classifying women by metabolic health may be of greater utility in identifying those at higher risk for endometrial cancer than anthropometry per se.

Association of body composition with risk of overall and site-specific cancers: A population-based prospective cohort study

Although excess adiposity has been linked with various cancers, association between body composition and some cancers remains unclear, like lung and prostate cancers. We investigated associations of body composition with risk of overall cancer and major site-specific cancers in a prospective cohort of 454 079 cancer-free participants from UK-Biobank. Body composition was measured with bioimpedance analysis. We evaluated hazard ratio (HR) and 95% confidence interval (CI) with multivariate Cox linear and nonlinear models in men and women separately. We identified 27 794 cancers over 7.6 years of follow-up. Multivariable adjusted models including fat-free mass (FFM) and fat mass (FM) showed that FFM was positively associated with overall cancer risk in men and women (HR 1.03, 95% CI 1.01-1.04 and 1.07, 1.04-1.10, respectively); while the association between FM and overall cancer disappeared after adjusting for FFM. FFM was associated with higher risks of obesity-related cancers combined, stomach (women only), malignant melanoma, postmenopausal breast, corpus uteri, prostate, kidney (men only), and blood cancers and lower risk of lung cancer. FM was associated with higher risks of obesity-related cancers combined, esophageal, colon, lung (men only), postmenopausal breast (at the lower end of FM range), and corpus uteri cancers and lower risks of rectal, malignant melanoma (women only), prostate and blood cancers. FFM and FM seemed to have different effects on cancer risk, and the effects varied substantially by cancer type, in both direction and size. Higher FM/FFM ratio was also associated with some cancers risk, and might be a useful predictor of cancer risk.

Body composition and risk of major gynecologic malignancies: Results from the UK Biobank prospective cohort

OBJECTIVE

To evaluate the association between body composition and subsequent risk of the major gynecologic malignancies.

METHODS

This is a prospective analysis of participants from the UK Biobank. We measured baseline body composition and confirmed cancer diagnosis through linkage to cancer and death registries. We evaluated hazard ratios (HRs) and confidence interval (CIs) with COX models adjusting for potential confounders.

RESULTS

We document 1430 cases of the top three gynecologic malignancies (uterine corpus cancer 847 cases, ovarian cancer 514 cases, and cervical cancer 69 cases) from 245,084 female participants (75,307 were premenopausal and 169,777 were postmenopausal). For premenopausal women, whole body fat-free mass (WBFFM) was associated with an increased risk of uterine corpus cancer (Adjusted HR per unit increase 1.04, 95% CI 1.02-1.06). For postmenopausal women, compared with the first quartile, the fourth quartile of WBFFM and whole body fat mass(WBFM) was associated with 2.16 (95% CI 1.49-3.13) times and 1.89 (95% CI 1.31-2.72) times of increased uterine corpus cancer risk, respectively. Regarding the distribution of body fat mass (FM)/fat-free mass (FFM), FFM distributed in the trunk was associate with increased uterine corpus cancer risk in premenopausal (HR 1.18,95% CI 1.07-1.31) and postmenopausal women (HR 1.13,95% CI 1.09-1.18). Meanwhile, FM/FFM distributed in the limbs present an U-shaped associations with uterine corpus cancer risk. We did not observe any association between aforementioned body composition indices with ovarian or cervical cancer.

CONCLUSION

FM is associated with an increased risk of uterine corpus cancer in postmenopausal women. Meanwhile, FFM is found to be a risk factor for uterine corpus cancer in both premenopausal and postmenopausal women. No association of body composition with ovarian or cervical cancer was observed.

Risk of female-specific cancers according to obesity and menopausal status in 2•7 million Korean women: Similar trends between Korean and Western women

BACKGROUND

Studies examining the relationship between obesity and female-specific cancers have been mainly conducted in Western populations. We aimed to investigate the risk of female-specific cancers according to obesity and menopausal status using a nationwide cohort in Korea.

METHODS

We identified 2,708,938 women from the National Health Insurance Service cohort, and obtained baseline body mass index (BMI), waist circumference (WC), and other healthcare data, measured and collected during a health examinations and cancer-screening survey. By setting a normal weight/WC group (BMI, 18•5-22•9 kg/m2 or WC, 80•0-84•9 cm) as the reference, we conducted multivariate analyses using the Cox proportional hazard model to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (95% CIs) for each cancer.

FINDINGS

The total follow-up duration was 22389854•63 person-years. In post-menopausal women, the risk of breast, endometrial, and ovarian cancers significantly increased as the BMI classification level increased from normal to class II obesity (aHRs [95% CIs], 1•49 [1•38-1.61], 2•11 [1•81-2•46], and 1•38 [1•20-1•58], respectively). The risk of breast and endometrial cancers also increased as the WC classification increased from < 75•0 to ≥ 95•0 cm. With a WC of 80•0-84•9 cm as the reference, the lowest risk of breast and endometrial cancers was observed in WC < 75•0 cm (aHRs [95% CIs], 0•85 [0•81-0•89] and 0•75 [0•67-0•84], respectively) while the highest risk was observed in WC ≥ 95•0 cm (aHRs [95% CIs], 1•19 [1•10-1•29] and 1•56 [1•33-1•82], respectively). In pre-menopausal women, the risk of breast cancer significantly decreased in those with class I and II obesity compared to those with normal BMI (aHRs [95% CIs], 0•96 [0•92-0•999] and 0•89 [0•81-0•97], respectively), whereas the trends of endometrial and ovarian cancer incidence in pre-menopausal women were similar to those observed in post-menopausal women. For cervical cancer, only class II obesity was significantly associated with increased risks in both post-menopausal and pre-menopausal women (aHRs [95% CIs], 1•18 [1•01-1•39] and 1•27 [1•02-1•57], respectively).

INTERPRETATION

In this large population-based cohort study in Korean women, we observed that the impact of obesity on the development of female-specific cancers differs according to the malignancy type and menopausal status. Similar trends were observed between Korean and Western women.

FUNDING

The Korea Health Industry Development Institute (no. HI16C2037).

The association of body fat composition with risk of breast, endometrial, ovarian and colorectal cancers among normal weight participants in the UK Biobank

BACKGROUND

The association between body fat composition and risk of cancer in normal weight individuals (body mass index (BMI) 18.5-24.9 kg/m2) is unclear.

METHODS

We examined the association of measures of adiposity with risk of incident cancers of the breast (postmenopausal), endometrium, ovary and colon/rectum among 149,928 normal weight individuals (40-70 years) who were enrolled in the UK Biobank cohort between 2006 and 2010.

RESULTS

All of the body fat measures were positively associated with invasive postmenopausal breast cancer risk (hazard ratios (HR) for the uppermost quintile (Q5) versus the lowest quintile (Q1) ranged from 1.32 (95% CI: 1.09-1.60) for waist circumference (WC) to 1.56 (1.28-1.90) for BMI). Trunk fat mass index (HRQ5 vs Q1: 1.72, 95% CI: 1.02-2.89) and WC (HRQ5 vs Q1: 1.65, 95% CI: 1.01-2.70)) were positively associated with risk of endometrial cancer. Among males, trunk fat:trunk fat free mass ratio, trunk fat:leg fat mass ratio and (HRQ5 vs Q1: 1.63, 95% CI: 1.02-2.60; 1.92, 1.20-3.07 and 1.68, 1.05-2.66, respectively) were positively associated with colon cancer risk. None of the body fat measures was associated with risk of ovarian cancer or colorectal cancer in women.

CONCLUSION

The findings of this study suggest that the current normal weight category based on BMI includes individuals who are at increased risk of some obesity-related cancers.

Associations of six adiposity-related markers with incidence and mortality from 24 cancers-findings from the UK Biobank prospective cohort study

BACKGROUND

Adiposity is a strong risk factor for cancer incidence and mortality. However, most of the evidence available has focused on body mass index (BMI) as a marker of adiposity. There is limited evidence on relationships of cancer with other adiposity markers, and if these associations are linear or not. The aim of this study was to investigate the associations of six adiposity markers with incidence and mortality from 24 cancers by accounting for potential non-linear associations.

METHODS

A total of 437,393 participants (53.8% women; mean age 56.3 years) from the UK Biobank prospective cohort study were included in this study. The median follow-up was 8.8 years (interquartile range 7.9 to 9.6) for mortality and 9.3 years (IQR 8.6 to 9.9) for cancer incidence. Adiposity-related exposures were BMI, body fat percentage, waist-hip ratio, waist-height ratio, and waist and hip circumference. Incidence and mortality of 24 cancers sites were the outcomes. Cox proportional hazard models were used with each of the exposure variables fitted separately on penalised cubic splines.

RESULTS

During follow-up, 47,882 individuals developed cancer and 11,265 died due to cancer during the follow-up period. All adiposity markers had similar associations with overall cancer incidence. BMI was associated with a higher incidence of 10 cancers (stomach cardia (hazard ratio per 1 SD increment 1.35, (95% CI 1.23; 1.47)), gallbladder (1.33 (1.12; 1.58)), liver (1.27 (1.19; 1.36)), kidney (1.26 (1.20; 1.33)), pancreas (1.12 (1.06; 1.19)), bladder (1.09 (1.04; 1.14)), colorectal (1.10 (1.06; 1.13)), endometrial (1.73 (1.65; 1.82)), uterine (1.68 (1.60; 1.75)), and breast cancer (1.08 (1.05; 1.11))) and overall cancer (1.03 (1.02; 1.04)). All these associations were linear except for breast cancer in postmenopausal women. Similar results were observed when other markers of central and overall adiposity were used. For mortality, nine cancer sites were linearly associated with BMI and eight with waist circumference and body fat percentage.

CONCLUSION

Adiposity, regardless of the marker used, was associated with an increased risk in 10 cancer sites.

Joint associations of physical activity and body mass index with the risk of established excess body fatness-related cancers among postmenopausal women

PURPOSE

Excess body fatness and physical activity independently influence the risk of several types of cancer. However, few studies have examined whether physical activity mitigates the excess risk associated with higher body mass index (BMI).

METHODS

We examined the individual and joint associations between BMI (kg/m²) and leisure-time moderate-to-vigorous physical activity (MVPA, MET-hours/week) with the risk of three established excess body fatness-related cancers (breast, colon, and endometrial) among 43,795 postmenopausal women in the Cancer Prevention Study II (CPS-II) Nutrition Cohort (1992/1993-2015). Further exclusions for women without an intact uterus resulted in 31,805 women for endometrial cancer analyses. Multivariable Cox proportional hazards regression was used to calculate hazard ratio (HR) and 95% confidence intervals (CIs) with interaction terms to assess multiplicative interaction. The relative excess risk due to interaction (RERI) was calculated to assess additive interaction.

RESULTS

BMI and MVPA were individually associated with breast and endometrial cancer risk, but only BMI was associated with colon cancer risk. In joint analyses, increasing levels of MVPA did not lower the risk of these cancers among obese women. For example, compared to the common referent (BMI 18.5- < 25 kg/m², MVPA > 0- < 7.5 MET-hours/week), BMI ≥ 30 kg/m² was associated with a higher risk of breast cancer among women with low MVPA (> 0-< 7.5 MET-hours/week: HR = 1.42, 95% CI: 1.22 - 1.67) and high MVPA (≥ 15 MET-hours/week: HR = 1.53, 95% CI: 1.25 - 1.87; RERI = 0.20, 95% CI: -0.14, 0.54, multiplicative P_interaction = 0.64).

CONCLUSION

Our results do not support the hypothesis that leisure-time physical activity mitigates the excess risk associated with higher BMI for risk of breast, endometrial, or colon cancer among postmenopausal women.