Lifetime physical activity and risk of endometrial cancer

Associations between transport modes and site-specific cancers: a systematic review and meta-analysis

BACKGROUND

Physical inactivity is a global public health problem. A practical solution would be to build physical activity into the daily routine by using active modes of transport. Choice of transport mode can influence cancer risk through their effects on levels of physical activity, sedentary time, and environmental pollution. This review synthesizes existing evidence on the associations of specific transport modes with risks of site-specific cancers.

METHODS

Relevant literature was searched in PubMed, Embase, and Scopus from 1914 to 17th February 2023. For cancer sites with effect measures available for a specific transport mode from two or more studies, random effects meta-analyses were performed to pool relative risks (RR) comparing the highest vs. lowest activity group as well as per 10 Metabolic Equivalent of Task (MET) hour increment in transport-related physical activity per week (∼150 min of walking or 90 min of cycling).

RESULTS

27 eligible studies (11 cohort, 15 case-control, and 1 case-cohort) were identified, which reported the associations of transport modes with 10 site-specific cancers. In the meta-analysis, 10 MET hour increment in transport-related physical activity per week was associated with a reduction in risk for endometrial cancer (RR: 0.91, 95% CI: 0.83-0.997), colorectal cancer (RR: 0.95, 95% CI: 0.91-0.99) and breast cancer (RR: 0.99, 95% CI: 0.89-0.996). The highest level of walking only or walking and cycling combined modes, compared to the lowest level, were significantly associated with a 12% and 30% reduced risk of breast and endometrial cancers respectively. Cycling, compared to motorized modes, was associated with a lower risk of overall cancer incidence and mortality.

CONCLUSION

Active transport appears to reduce cancer risk, but evidence for cancer sites other than colorectum, breast, and endometrium is currently limited.

Global incidence and mortality trends of corpus uteri cancer and associations with gross domestic product, human development index, lifestyle, and metabolic risk factors

OBJECTIVE

To evaluate the worldwide distribution, risk factors, and temporal trends of corpus uteri cancer for different countries and age groups.

METHOD

Data relating to corpus uteri cancer in 2020 were retrieved from the Global Cancer Observatory database. Data from Cancer Incidence in Five Continents and the WHO mortality database were used for trend analysis. Age-standardized rates (ASR, per 100 000 persons) were calculated for incidence and mortality. Joinpoint regression analysis was used to estimate the 10-year annual average percent change (AAPC).

RESULTS

A total of 417 367 new cases and 97 370 new deaths of corpus uteri cancer were reported globally in 2020. The highest incidence was observed in high-income countries. Higher ASR of mortality of corpus uteri cancer was associated with a higher gross domestic product per capita, higher Human Development Index, and higher prevalence of smoking, alcohol drinking, physical inactivity, obesity, hypertension, diabetes, and lipid disorders. There was a substantial increasing trend of corpus uteri cancer, with the largest AAPC in incidence found in Japan, followed by India, Chile, Korea, and Thailand.

CONCLUSION

The incidence and mortality of corpus uteri cancer have been increasing substantially for the past 10 years. Intensive lifestyle modifications are needed, especially among younger women.

Trajectory of physical activity frequency and cancer risk: Findings from a population-based cohort study

BACKGROUND

Physical activity (PA) changes throughout an individual's life, but the association between such changes and cancer risk seems to be overlooked in the literature. Thus, this study aimed to examine the association between the trajectories of PA frequency and cancer incidence among middle-aged Korean adults.

METHODS

A total of 1,476,335 eligible participants (992,151 men and 484,184 women) aged ≥40 years from the National Health Insurance Service cohort (2002-2018) were included. Assessment of PA frequency was a self-reported measure, based on the question: "How many times per week do you perform exercise that makes you sweat?". PA frequency trajectories (i.e., trajectory classes of change in PA frequency) from 2002 to 2008 were identified using group-based trajectory modeling. Cox proportional hazards regression was used to assess the associations between the PA trajectories and cancer incidence.

RESULTS

Five PA frequency trajectories over 7 years were identified: persistently low (men:73.5%; women:74.7%), persistently moderate (men:16.2%; women:14.6%), high-to-low (men:3.9%; women:3.7%), low-to-high (men:3.5%; women:3.8%), and persistently high (men:2.9%; women:3.3%). Compared with persistently low frequency, maintaining a high PA frequency was associated with a lower risk of all cancers (Hazard ratio (HR) = 0.92, 95%CI = 0.87-0.98) and breast cancer (HR = 0.82, 95%CI = 0.70-0.96) among women. There was a lower risk for thyroid cancer among men in the high-to-low (HR = 0.83, 95%CI = 0.71-0.98), low-to-high (HR = 0.80, 95%CI = 0.67-0.96), and high PA trajectories (HR = 0.82, 95%CI = 0.68-0.99). There was a significant association between moderate trajectory and lung cancer in men (HR = 0.88, 95%CI = 0.80-0.95), in both smoking and non-smoking men.

CONCLUSION

Long-term persistent high frequency of PA as part of the daily routine should be widely promoted and encouraged to reduce the risk for all cancer development in women.

Quantifying the Effect of Physical Activity on Endometrial Cancer Risk

Endometrial cancer incidence is rising, with 435,000 global cases in 2019. An effective, low-cost primary prevention strategy is required to reduce disease burden. Obesity, insulin resistance, and inflammation contribute to endometrial carcinogenesis and physical activity targets these pathways. This study sought to quantify the amount of physical activity required to impact upon endometrial cancer risk. Physical activity data from 222,031 female participants with an intact uterus in the UK Biobank study were analyzed using a multivariable Cox proportional hazards model. A systematic review of the literature was performed, searching CENTRAL, Embase, and MEDLINE databases up to April 19, 2021. Studies including participants with and without endometrial cancer investigating the effect of physical activity measured in MET-hours/week (MET-h/week) on disease risk were included. Two reviewers independently selected studies, extracted data, and evaluated the risk of bias. Within the UK Biobank, each 1 MET-h/week increase in total physical activity was associated with a 0.2% [95% confidence interval (CI), 0.1-0.4; P = 0.020] reduction in endometrial cancer risk, equating to a 10.4% reduction if performing 50 MET-h/week or 7 hours of jogging per week. Eleven cohort and 12 case-control studies were identified in the systematic review, including 821,599 participants. One study reported a nonsignificant effect of 1 MET-h/week increases in physical activity on endometrial cancer risk (OR, 1.00; 95% CI, 0.99-1.00). Eight studies found significant reductions in disease risk of 15%-53%, but only in the most physically active individuals. Physical activity reduces endometrial cancer risk, but the effect size appears small. Regular vigorous activity should be encouraged to maximize the health benefit observed.

PREVENTION RELEVANCE

Effective, low-cost primary prevention strategies are urgently needed to tackle the rapid global increase in endometrial cancer. We sought to quantify the effect of physical activity on endometrial cancer risk, noting a linear inverse relationship influenced by body mass index. The most beneficial type and amount of activity remain unclear.

Metabolic Activity of Visceral Adipose Tissue Is Associated with Metastatic Status of Lymph Nodes in Endometrial Cancer: A 18F-FDG PET/CT Study

Obesity contributes to increased cancer incidence and aggressiveness in patients with endometrial cancer. Inflamed metabolic activity of visceral adipose tissue (VAT) is regarded as a key underlying mechanism of adverse consequences of obesity. The aim of this study was to investigate the association between inflammatory metabolic activity of VAT evaluated by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and metastatic status of lymph nodes (LN) in patients with endometrial cancer. In total, 161 women with newly diagnosed endometrial cancer, who received preoperative 18F-FDG PET/CT, were enrolled. VAT inflammatory metabolic activity was defined as V/S ratio and measured from the maximum standardized uptake value (SUVmax) of VAT normalized to the SUVmax of subcutaneous adipose tissue (SAT). The positive LN metastasis group exhibited a significantly higher V/S ratio than the negative LN metastasis group. Systemic inflammatory surrogate markers including high sensitivity C-reactive protein, spleen SUVmax, and bone marrow SUVmax were also higher in the LN metastasis group than in the negative LN metastasis group, showing significant correlations with V/S ratio. In multivariate logistic regression analysis, V/S ratio was independently associated with LN metastasis. V/S ratio is independently associated with the LN metastasis status in patients with endometrial cancer. This finding could be useful as a potential surrogate marker of obesity-induced VAT inflammation associated with tumor aggressiveness.

Influence of physical activity at a young age and lifetime physical activity on the risks of 3 obesity-related cancers: systematic review and meta-analysis of observational studies

CONTEXT

Excess weight has been linked to increased risks of 13 types of cancers. Physical activity is a non-nutritional modifiable lifestyle factor that is not only crucial for weight control but is also known to regulate hormones and metabolic pathways that may contribute to carcinogenesis. There is solid evidence that being physically active during middle and late adulthood lowers the risks of 3 obesity-related cancers, namely breast cancer, colon cancer, and endometrial cancer. However, the associations between physical activity at a young age (childhood, adolescence, and young adulthood; age 5 to ≤30 yr) and lifetime physical activity and the risks of breast cancer, colon cancer, and endometrial cancer are less defined.

OBJECTIVE

The present systematic review and meta-analysis of observational studies was performed in accordance with the MOOSE guidelines to determine whether physical activity at a young age and lifetime physical activity may lower the risks of breast cancer, colon cancer, and endometrial cancer.

DATA SOURCES

The PubMed and Web of Science databases were searched for relevant observational studies published from inception to July 2018.

STUDY SELECTION

Observational studies (prospective cohort, case-cohort, nested case-control, historical cohort, and case-control) were considered relevant if they investigated the association between physical activity at a young age or lifetime physical activity and the risks of developing selected cancers.

DATA EXTRACTION

A random-effects meta-analysis was performed to generate the summary relative risk (RR) with 95%CI for the highest vs the lowest category of physical activity of any type.

RESULTS

Eighty publications were included in the present meta-analysis. Higher physical activity at a young age was associated with lower risks of breast cancer (RR 0.81, 95%CI 0.76, 0.87) and colon cancer (RR 0.67, 95%CI 0.50, 0.88). Similarly, lifetime physical activity was inversely associated with the risks of breast cancer (RR 0.79, 95%CI 0.72, 0.86) and colon cancer (RR 0.75, 95%CI 0.69, 0.82). For breast cancer, menopausal status did not appear to modify the observed inverse association. The benefit with respect to endometrial cancer risk reduction was only observed with higher lifetime physical activity (RR 0.77, 95%CI 0.67, 0.88), not with higher physical activity at a young age (RR 0.89, 95%CI 0.73, 1.07).

CONCLUSIONS

Being physically active over a lifetime, starting from early childhood, may lower the risks of developing breast cancer, colon cancer, and endometrial cancer.

Physical Activity: Impact on Survival in Gynecologic Cancer

Importance

Physical activity has many important health benefits. There is also growing evidence that physical activity plays a role in the prevention and prognosis of multiple cancers, including gynecologic malignancies. Despite the many benefits of physical activity, the number of individuals meeting physical activity recommendations remains low.

Objective

To examine the role that physical activity plays in the prevention, treatment, and prognosis of gynecologic malignancies and to review the feasibility of physical activity interventions among gynecologic cancer survivors.

Evidence Acquisition

A PubMed search was performed using relevant terms to identify journal articles related to the proposed subject. The websites of multiple national and international organizations were also used to obtain up-to-date guidelines and recommendations.

Results

Physical activity appears to decrease the risk of ovarian, endometrial, and cervical cancer, with the strongest evidence of this association seen in endometrial cancer. Although the literature is scarce, participation in physical activity is feasible during active treatment for gynecologic cancers and may decrease symptom burden and increase chemotherapy completion rates. Gynecologic cancer survivors are motivated to increase physical activity, and lifestyle intervention programs are feasible and well received among this population.

Conclusions and Relevance

Health care providers caring for women with gynecologic malignancies must counsel patients regarding the importance of physical activity. This should include a discussion of the health benefits and, specifically, the cancer-related benefits. A personalized approach to physical activity intervention is essential.

Effect of Physical Activity on Quality of Life as Perceived by Endometrial Cancer Survivors: A Systematic Review

PURPOSE

A combination of the relatively high prevalence among gynecologic cancers, high survival, and the myriads of factors that negatively impact the quality of life (QoL) among endometrial cancer (EC) survivors underscores the potential benefits of meeting guideline physical activity (PA) guidelines of 150 minutes per week among EC survivors. The objective of the present systematic review was to collate and critically evaluate the currently available literature on the effects of PA on QoL among EC survivors.

METHODS

Medline and Web of Science databases were searched for articles on EC, QoL, and PA. We also inspected bibliographies of relevant publications to identify related articles. Our search criteria yielded 70 studies, 7 of which met the inclusion criteria.

RESULTS

Of the 7 studies examined, 2 of them were intervention studies, whereas 5 were cross-sectional studies. Meeting guideline PA was significantly associated with better QoL score in 4 of the 5 cross-sectional studies.

CONCLUSIONS

Results from the cross-sectional studies suggest that EC survivors' inactivity is significantly correlated with poorer QoL. This correlation was worse among obese survivors compared with normal weight survivors. Endometrial cancer survivors may benefit from interventions that incorporate PA. More randomized intervention studies among EC survivors are needed to add to this body of evidence.

Incidence and lifetime risk of uterine corpus cancer in Taiwanese women from 1991 to 2010

OBJECTIVE

Although uterine corpus cancer has been the most common malignancy of the female genital tract in many countries, the lifetime risk of this cancer has not yet been determined among Taiwanese women. The purpose of the study was to describe the change in incidence and the lifetime risk of uterine corpus cancer over a 20-year period from 1991 to 2010 in Taiwan.

MATERIALS AND METHODS

We conducted a population-based registry study using the released database (available online) from the Taiwan Cancer Registry.

RESULTS

A total of 15,542 women newly diagnosed with uterine corpus cancer were included in this study. The total number of this cancer increased by 5.7-fold from 1991 to 2010. The annual age-specific rate nearly doubled during the past decade (2001-2010) when compared with the previous decade (1991-2000). Incidence rates were highest in women aged 50-59 years, and increasing incidence rates were observed in each age strata starting from 40 years to 85 years and more, after the year 2000. The lifetime risk of being diagnosed with uterine corpus cancer was 0.39% in 1991-1995, 0.54% in 1996-2000, 0.73% in 2001-2005, and 1.12% in 2006-2010 among Taiwanese women.

CONCLUSION

According to the observed changes in incidence rate, the burden of uterine corpus cancer in the general female population is expected to increase in the near future. From a public-health perspective, care providers should develop strategies for the prevention, early detection, and intervention to reduce the rapidly increasing incidence of uterine corpus cancer in Taiwan.

Obesity and Endometrial Cancer

Endometrial cancer is the sixth most common cancer in women worldwide and the most common gynecologic malignancy in the developed world. This chapter explores the current epidemiologic evidence on the association between obesity and endometrial cancer risk and mortality. Using body mass index (BMI) as a measure of obesity, we found that obesity (defined as BMI > 30 and < 35 kg/m²) was associated with a 2.6-fold increase in endometrial cancer risk, while severe obesity (BMI > 35 kg/m²) was associated with a 4.7-fold increase compared to normal-weight women (BMI < 25 kg/m²). Increased central adiposity also increased endometrial cancer risk by 1.5- to twofold. Among both healthy and endometrial cancer patient populations, obesity was associated with a roughly twofold increase in endometrial cancer-specific mortality. This risk reduction was also observed for obesity and all-cause mortality among endometrial cancer patients. In the few studies that assessed risk associated with weight change, an increased endometrial cancer risk with weight gain and weight cycling was observed, whereas some evidence for a protective effect of weight loss was found. Furthermore, early-life obesity was associated with a moderately increased risk of endometrial cancer later in life. There are several mechanisms whereby obesity is hypothesized to increase endometrial cancer risk, including increased endogenous sex steroid hormones, insulin resistance, chronic inflammation and adipokines. Further research should focus on histological subtypes or molecular phenotypes of endometrial tumors and population subgroups that could be at an increased risk of obesity-associated endometrial cancer. Additionally, studies on weight gain, loss or cycling and weight loss interventions can provide mechanistic insight into the obesity-endometrial cancer association. Sufficient evidence exists to recommend avoiding obesity to reduce endometrial cancer risk.

Endometrial cancer and oral contraceptives: an individual participant meta-analysis of 27 276 women with endometrial cancer from 36 epidemiological studies

BACKGROUND

Oral contraceptives are known to reduce the incidence rate of endometrial cancer, but it is uncertain how long this effect lasts after use ceases, or whether it is modified by other factors.

METHODS

Individual participant datasets were sought from principal investigators and provided centrally for 27 276 women with endometrial cancer (cases) and 115 743 without endometrial cancer (controls) from 36 epidemiological studies. The relative risks (RRs) of endometrial cancer associated with oral contraceptive use were estimated using logistic regression, stratified by study, age, parity, body-mass index, smoking, and use of menopausal hormone therapy.

FINDINGS

The median age of cases was 63 years (IQR 57-68) and the median year of cancer diagnosis was 2001 (IQR 1994-2005). 9459 (35%) of 27 276 cases and 45 625 (39%) of 115 743 controls had ever used oral contraceptives, for median durations of 3·0 years (IQR 1-7) and 4·4 years (IQR 2-9), respectively. The longer that women had used oral contraceptives, the greater the reduction in risk of endometrial cancer; every 5 years of use was associated with a risk ratio of 0·76 (95% CI 0·73-0·78; p<0·0001). This reduction in risk persisted for more than 30 years after oral contraceptive use had ceased, with no apparent decrease between the RRs for use during the 1960s, 1970s, and 1980s, despite higher oestrogen doses in pills used in the early years. However, the reduction in risk associated with ever having used oral contraceptives differed by tumour type, being stronger for carcinomas (RR 0·69, 95% CI 0·66-0·71) than sarcomas (0·83, 0·67-1·04; case-case comparison: p=0·02). In high-income countries, 10 years use of oral contraceptives was estimated to reduce the absolute risk of endometrial cancer arising before age 75 years from 2·3 to 1·3 per 100 women.

INTERPRETATION

Use of oral contraceptives confers long-term protection against endometrial cancer. These results suggest that, in developed countries, about 400 000 cases of endometrial cancer before the age of 75 years have been prevented over the past 50 years (1965-2014) by oral contraceptives, including 200 000 in the past decade (2005-14).

FUNDING

Medical Research Council, Cancer Research UK.

A systematic review and meta-analysis of physical activity and endometrial cancer risk

Physical activity is related to decreased endometrial cancer risk. However, a comprehensive investigation of activity domains, intensities, time periods in life, and potential interaction with body mass index is unavailable. We performed a meta-analysis of physical activity and endometrial cancer studies published through October 2014. We identified 33 eligible studies comprising 19,558 endometrial cancer cases. High versus low physical activity was related to reduced endometrial cancer risk [relative risk (RR) = 0.80; 95% confidence interval (CI) 0.75-0.85]. The corresponding RRs for recreational activity, occupational activity, household activity, and walking were 0.84 (95% CI 0.78-0.91), 0.81 (95% CI 0.75-0.87), 0.70 (95% CI 0.47-1.02), and 0.82 (95% CI 0.69-0.97), respectively (Pdifference). Walking/biking for transportation, walking for recreation, and walking without specification revealed summary RRs of 0.70 (95% CI 0.58-0.85), 0.94 (95% CI 0.76-1.17), and 0.88 (95% CI 0.52-1.50), respectively (Pdifference). Inverse associations were noted for light (RR 0.65; 95% CI 0.49-0.86), moderate to vigorous (RR 0.83; 95 % CI 0.71-0.96), and vigorous activity (RR 0.80; 95% CI 0.72-0.90; (Pdifference). A statistically significant inverse relation was found for postmenopausal (RR 0.81; 95% CI 0.67-0.97), but not premenopausal women (RR 0.74; 95% CI 0.49-1.13; (Pdifference). Physical activity performed during childhood/adolescence, young adulthood/midlife, and older age yielded RRs of 0.94 (95% CI 0.82-1.08), 0.77 (95% CI 0.58-1.01), and 0.69 (95% CI 0.37-1.28), respectively (Pdifference). An inverse relation was evident in overweight/obese (RR 0.69; 95% CI 0.52-0.91), but not normal weight women (RR 0.97; 95% CI 0.84-1.13; (Pdifference). In conclusion, recreational physical activity, occupational physical activity, and walking/biking for transportation are related to decreased endometrial cancer risk. Inverse associations are evident for physical activity of light, moderate to vigorous, and vigorous intensities. The inverse relation with physical activity is limited to women who are overweight or obese.

Response to an exercise intervention after endometrial cancer: differences between obese and non-obese survivors

OBJECTIVE

The objective of this paper is to describe baseline differences between obese and non-obese endometrial cancer survivor in anthropometrics, exercise behavior, fitness, heart rate and blood pressure, and quality of life, and to analyze whether the effect of a home-based exercise intervention on these outcomes differed for obese and non-obese participants.

METHODS

One hundred post-treatment Stage I-IIIa endometrial cancer survivors participated in a single arm 6month study in which they received a home-based exercise intervention. Cardiorespiratory fitness, anthropometrics, and exercise behavior were measured every two months, and quality of life (QOL) and psychological distress were measured at baseline and 6months.

RESULTS

Adjusting for potential confounders, at baseline obese survivors had poorer cardiorespiratory fitness (p=.002), higher systolic blood pressure (p=.018), and lower physical functioning (p<.001) and ratings of general health (p=.002), and more pain (p=.037) and somatization (.002). Significant improvements were seen in exercise behavior, resting heart rate, systolic blood pressure, and multiple QOL domains over the course of the intervention. Obese survivors had less improvement in exercise behavior and cardiorespiratory fitness than non-obese survivors, but there were no differences with regard to improvements in QOL and stress.

CONCLUSIONS

Home based exercise interventions are beneficial to endometrial cancer survivors, including those whose BMI is in the obese range. While obese survivors have lower levels of physical activity and fitness, they experienced similar activity, fitness, quality of life and mental health benefits. Exercise should be encouraged in endometrial cancer survivors, including those who are obese.

Overweight, obesity and endometrial cancer risk: results from a systematic review and meta-analysis

AIM

Findings from recent studies suggest that obesity may be associated with an increased risk of endometrial cancer, but several earlier studies were less conclusive. Here we strive to estimate this relationship in a meta-analysis of published data.

METHODS

We searched Pubmed and Embase for studies on body mass index and the risk of endometrial cancer, published from 1989 to 2011. Data were independently extracted and analyzed using random or fixed effects meta-analysis depending on the degree of heterogeneity.

RESULTS

Seven cohort studies and 11 case-control studies were included in the meta-analysis. Overall, the conditions of excess body weight ([EBW] defined as body mass index [BMI] ≥25 kg/m²), obesity (BMI ≥30 kg/m²) and overweight (25< BMI <30 kg/m²) were associated with an increased risk of endometrial cancer (relative risk [RR] for EBW=1.62, 95% confidence interval [CI], 1.39-1.89; for obesity RR=2.54, 95% CI, 2.11-3.06; for overweight RR=1.32, 95% CI, 1.16-1.50). Subgroup analyses showed that the positive associations were independent of study design, geographic locations, self-reported BMI, alcohol use, smoking habit, history of diabetes, hormone therapy, age at menarche, age at menopause, parity, and age at first full term pregnancy. However, there was no statistically significant association between EBW and endometrial cancer risk for measured BMI (for EBW RR=1.29, 95% CI, 0.66-2.53).

CONCLUSIONS

The findings from this meta-analysis strongly support that the conditions of EBW, overweight, and obesity are all associated with an increased risk of endometrial cancer. Also, the strength of the association increases with increasing BMI.

Sitting time, physical activity and cervical intraepithelial neoplasia in Australian women: a preliminary investigation

ISSUE ADDRESSED

Physical activity affects the immune system, which in turn may modify the risk of cervical intraepithelial neoplasia (CIN). The effect of sitting on CIN is unknown. This study investigated the relationship between sitting time, physical activity and the risk of CIN.

METHODS

Community-dwelling adult women within metropolitan Perth, Western Australia, who had had a Papanicolaou (Pap) smear test at any of five clinics and medical centres, were approached by their general practitioners. In total, 348 women were recruited and interviewed for information on sitting time, physical activity level and lifetime physical activity exposure using the International Physical Activity Questionnaire (IPAQ)--short form. Associations of exposure variables with CIN risk were assessed by unconditional logistic regression analyses.

RESULTS

The prevalence of abnormal Pap smear status indicating CIN was found to be 15.8%. Women with prolonged sitting duration (≥42 h per week) had significantly increased risk of CIN (adjusted OR 3.49, 95% CI 1.12-10.88) than women who sat less than 24.5h per week. Although the effect of total physical activity level was non-significant (P=0.408), being always involved in physical activity during the entire life appeared to be inversely associated with the CIN risk (P=0.036).

CONCLUSIONS

Prolonged sitting time was significantly associated with increased risk of abnormal Pap smear status indicating CIN. SO WHAT?: This preliminary investigation highlights a new prospect for health-promotion intervention to reduce the risk of CIN. Health practitioners should encourage women to reduce their sitting time and maintain physically active throughout their life course.

Long-term and baseline recreational physical activity and risk of endometrial cancer: the California Teachers Study

BACKGROUND

Physical activity may be associated with decreasing endometrial cancer risk; it remains unclear whether the association is modified by body size.

METHODS

Among 93 888 eligible California Teachers Study participants, 976 were diagnosed with incident endometrial cancer between 1995-1996 and 2007. Cox proportional hazards regression methods were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for endometrial cancer associated with long-term (high school through age 54 years) and baseline (3 years prior to joining the cohort) strenuous and moderate recreational physical activity, overall and by body size.

RESULTS

Increased baseline strenuous recreational physical activity was associated with decreased endometrial cancer risk (Ptrend=0.006) with approximately 25% lower risk among women exercising >3 h per week per year than among those exercising <1/2 h per week per year (RR, 0.76; 95% CI, 0.63-0.92). This inverse association was observed among overweight/obese women (body mass index ≥25 kg m(-2); Ptrend=0.006), but not among thinner women (Ptrend=0.12). Baseline moderate activity was associated with lower risk among overweight/obese women.

CONCLUSION

Increasing physical activity, particularly strenuous activity, may be a lifestyle change that overweight and obese women can implement to reduce their endometrial cancer risk.

Invited commentary: are dietary intakes and other exposures in childhood and adolescence important for adult cancers?

In this issue of the Journal, Nimptsch et al. (Am J Epidemiol. 2013;178(2):172-183) report significant associations between female adolescents' poultry consumption in high school and subsequent reduced risk of colorectal adenomas in adulthood. Consumption of red meat or fish was not related to risk, but replacement with poultry reduced the risk of later adenomas. Most epidemiologic studies of adult diseases lack exposure data from the distant past. By focusing on a cancer precursor lesion and using a variety of methods to assess data quality, the investigators address concerns about the quality of distant recall. These findings add to the growing evidence that links childhood and adolescent lifestyle and environmental exposures with subsequent risk of cancers arising in adulthood. Highlights of the literature on this topic and methodological challenges are summarized. Future studies would benefit from incorporating measures of lifestyle, diet, environmental exposures, and other risk factors from early in life and from validation and other data quality checks of such measurements. Sources of historical data on children's and adolescents' exposures should be sought and evaluated in conjunction with subsequent exposures in relationship to adult-onset cancers.

Contemporary clinical management of endometrial cancer

Although the contemporary management of endometrial cancer is straightforward in many ways, novel data has emerged over the past decade that has altered the clinical standards of care while generating new controversies that will require further investigation. Fortunately most cases are diagnosed at early stages, but high-risk histologies and poorly differentiated tumors have high metastatic potential with a significantly worse prognosis. Initial management typically requires surgery, but the role and extent of lymphadenectomy are debated especially with well-differentiated tumors. With the changes in surgical staging, prognosis correlates more closely with stage, and the importance of cytology has been questioned and is under evaluation. The roles of radiation in intermediate-risk patients and chemotherapy in high-risk patients are emerging. The therapeutic index of brachytherapy needs to be considered, and the best sequencing of combined modalities needs to balance efficacy and toxicities. Additionally novel targeted therapies show promise, and further studies are needed to determine the appropriate use of these new agents. Management of endometrial cancer will continue to evolve as clinical trials continue to answer unsolved clinical questions.

Physical activity and cancer

Epidemiological evidence continues to accumulate on the benefits of physical activity in relation to cancer risk, progression and mortality. Recent studies suggest that sedentary behavior may independently affect cancer risk; they also focus on factors that may explain associations with physical activity, including cancer risk factors and whether associations exist for precancerous lesions. Despite enormous efforts to examine associations between physical activity and cancer, the literature is hindered by inconsistent assessment of physical activity across studies, and incomplete consideration of variation of effects across population subgroups (for example, defined by body size, age or sex) or tumors subgroups (organ location, receptor status, or molecular subtype), and whether other factors explain study results. Clearly, public health recommendations for appropriate changes in activity levels are needed; unfortunately, at this time, we have no exact physical activity prescription to give to the public.

Assessment of the effects of severe obesity and lifestyle risk factors on stage of endometrial cancer

BACKGROUND

Lifestyle risk factors, including obesity, have been associated with increased risk of endometrial cancer (EC). Women with higher obesity levels tend to have less aggressive EC disease stage and histology. This study further investigated associations between nonmodifiable risk factors, such as age, race, and grade, and modifiable lifestyle factors, such as diet and physical activity expenditure, in relation to severe obesity and late versus early EC stage at diagnosis.

METHODS

Demographic, anthropometric, and lifestyle surveys were administered to 177 women with histologically confirmed EC. Logistic regression analyses assessed the relationship between obesity and other risk factors on EC stage at diagnosis.

RESULTS

In multivariate models, body mass index (BMI) < 35 was not significantly associated with late EC stage at diagnosis (OR = 1.67, P = 0.219) when adjusting for grade and age. Grade was significantly associated with EC stage when controlling for BMI and age (OR = 8.48, P = .000). Women more than the age of 60 had a fourfold increased risk of diagnosis at late versus early EC stage when adjusting for other risk factors. Age had a confounding effect on the obesity-EC stage association.

CONCLUSIONS

Our results corroborate those of past studies showing that BMI is not an independent risk factor for EC stage and that age may have confounded the obesity-EC stage association. Because of mixed results and implications for treatment outcomes, however, further research examining these variables is warranted.

IMPACT

Our results provide further insight into the obesity EC-stage association, especially the confounding effect of age. Future studies should examine modifiable lifestyle factors in larger and more diverse populations.

Malignant tumors of the female reproductive system

This review summarizes the epidemiology of cancer of the female reproductive system and associated lifestyle factors. It also assesses the available evidence for occupational factors associated with these cancers. Cervical, endometrial, and ovarian cancers are relatively common, and cause significant cancer morbidity and mortality worldwide, whereas vulvar, vaginal, fallopian tube cancers, and choriocarcinomas are very rare. As several lifestyle factors are known to play a major role in the etiology of these cancers, very few published studies have investigated possible relationships with occupational factors. Some occupational exposures have been associated with increased risks of these cancers, but apart from the available evidence on the relationships between asbestos fibers and ovarian cancer, and tetrachloroethylene and cervical cancer, the data is rather scarce. Given the multifactorial nature of cancers of the female reproductive system, it is of the utmost importance to conduct occupational studies that will gather detailed data on potential individual confounding factors, in particular reproductive history and other factors that influence the body's hormonal environment, together with information on socio-economic status and lifestyle factors, including physical activity from multiple sources. Studies on the mechanisms of carcinogenesis in the female reproductive organs are also needed in order to elucidate the possible role of chemical exposures in the development of these cancers.

Shifting the paradigm in radiation safety

The current radiation safety paradigm using the linear no-threshold (LNT) model is based on the premise that even the smallest amount of radiation may cause mutations increasing the risk of cancer. Autopsy studies have shown that the presence of cancer cells is not a decisive factor in the occurrence of clinical cancer. On the other hand, suppression of immune system more than doubles the cancer risk in organ transplant patients, indicating its key role in keeping occult cancers in check. Low dose radiation (LDR) elevates immune response, and so it may reduce rather than increase the risk of cancer. LNT model pays exclusive attention to DNA damage, which is not a decisive factor, and completely ignores immune system response, which is an important factor, and so is not scientifically justifiable. By not recognizing the importance of the immune system in cancer, and not exploring exercise intervention, the current paradigm may have missed an opportunity to reduce cancer deaths among atomic bomb survivors. Increased antioxidants from LDR may reduce aging-related non-cancer diseases since oxidative damage is implicated in these. A paradigm shift is warranted to reduce further casualties, reduce fear of LDR, and enable investigation of potential beneficial applications of LDR.

The epidemiology of endometrial and ovarian cancer

This review highlights similarities in the epidemiology of endometrial and ovarian cancer, including highly correlated incidence rates and similar risk factor profiles. Factors that decrease risk for both cancers include a late menarche, early age at first birth, giving birth and breastfeeding, and use of oral contraceptives. Short or irregular cycles and late menopause are associated with increased risk for both. Other risk factors that appear to operate in a similar direction include decreased risk associated with IUD use or a tubal ligation, and increased risk associated with obesity, lack of exercise, and use of talc powders in genital hygiene. Estrogen excess is proposed as the underlying mechanism for most endometrial cancers, whereas incessant ovulation has been suggested as the explanation for ovarian cancer. However, an increased number of estimated ovulatory cycles correlates directly with risk for both endometrial and ovarian cancer, suggesting that reproductive tissue turnover with an accumulation of PTEN or p53 mutations represents a possible common mechanism. An immune-based explanation involving mucin proteins represents another common mechanism that could explain additional risk factors. Maintenance of ideal weight, breastfeeding children, use of oral contraceptives, and avoidance of talc powders in genital hygiene are measures that could lower the risk for both types of cancer. Careful selection of patients for prophylactic oophorectomy for those women who are coming to hysterectomy for benign disease is an additional measure to consider for ovarian cancer.

Physical activity and endometrial cancer in a population-based case-control study

INTRODUCTION

Published studies of physical activity, BMI, and endometrial cancer risk show conflicting results and many do not report on reliability or validity of physical activity questionnaires.

METHODS

We collected physical activity data on 667 incident cases of endometrial cancer and 662 age-matched controls. Interview-administered questionnaires, collecting demographic and lifestyle information, including a validated questionnaire for physical activity. We performed unconditional logistic regression to examine the relationship between moderate- to vigorous-intensity sports/recreational physical activity (MV PA), sit time, and endometrial cancer risk.

RESULTS

Compared to women reporting 0 metabolic equivalent (MET) hours per week of MV PA, those who reported 7.5 MET h/wk or more had a 34% lower endometrial cancer risk (odds ratio (OR) = 0.66, 95% CI 0.50-0.87) after adjusting for risk factors including BMI. Those women sitting more than 8 h per day had a 52% increased odds (95% CI 1.07-2.16) of endometrial cancer compared to those sitting less than 4 h per day. We created a composite measure of physical activity and BMI and found that women with a BMI <25 and activity levels ≥7.5 MET h/wk had a 73% lower endometrial cancer risk (OR = 0.27, 95% CI 0.18-0.39) compared with the reference group of overweight (BMI ≥25) and sedentary (MET h/wk = 0).

CONCLUSION

Our data support an inverse, independent association between physical activity and endometrial cancer risk after adjusting for BMI and other risk factors.