Long-term sedentary work and the risk of subsite-specific colorectal cancer

Deciphering the impact of dietary habits and behavioral patterns on colorectal cancer

Colorectal cancer (CRC) is a malignant tumor that originates from the epithelial cells of the colon and rectum. Global epidemiological data shows that in 2020, the incidence and mortality rate of CRC ranked third and second, respectively, posing a serious threat to people's health and lives. The factors influencing CRC are numerous and can be broadly categorized as modifiable and non-modifiable based on whether they can be managed or intervened upon. Non-modifiable factors include age, gender, family history, among others. Among the modifiable factors, dietary habits and behavioral practices are the main intervention measures that people can take to prevent CRC. Numerous studies indicate that a high intake of red and processed meats, fats, as well as habits such as smoking, alcohol consumption, and prolonged sitting, increase the risk of developing CRC. Conversely, consuming ample vegetables, fruits, high dietary fiber, and engaging in moderate regular exercise may reduce the risk of CRC. This article primarily discusses the impact of dietary habits and behavioral practices on the occurrence and development of CRC, along with possible mechanisms, laying the foundation and providing direction for the prevention and control of CRC occurrence and development.

Synchronous or metachronous breast and colorectal cancers in younger-than-average-age patients: a case series

BACKGROUND

The incidence of breast and colorectal cancer (CRC) in younger-than-average-age patients is rising and poorly understood. This is the largest study on patients with both cancers who are less than 60 years old and aims to characterize demographic, clinicopathologic, and genetic features and describe therapeutic dilemmas and management strategies.

MATERIALS AND METHODS

This is a retrospective medical records review of patients at the University of California San Francisco with both primary breast and CRC before age 60.

RESULTS

Fifty-one patients were identified; 41 had detailed medical records. Median age of diagnosis with breast cancer was 43 (range 27-59) and CRC was 50 (28-59). Most were Caucasian (38, 74.5%) and never smokers (23, 56.1%); about half were current alcohol consumers (20, 48.8%) and about one-third had sedentary jobs (14, 34.1%). Average BMI was 25.8 (range: 14-49), and 30% were overweight or obese. Breast was the first cancer diagnosed in 36 patients (70.6%) and 44 (86.3%) had a metachronous CRC diagnosis. Breast cancer was early stage (0-2) in 32 (78.0%) patients whereas CRC was split between early stage (1-2) in 14 (34.1%) and later stage (3-4) in 19 (46.2%). Ten patients (24.3%) had a known germline mutation, although 23 (56.1%) had a family history of cancer in a first-degree relative.

CONCLUSION

Younger patients with both breast and CRC are a unique cohort, often without known risk factors. Alcohol consumption and sedentary jobs were the most common risk factors, and about one-quarter had a known genetic predisposition. Comanagement of both cancers requires individualized, multidisciplinary care.

Exercise and colorectal cancer: prevention and molecular mechanisms

Exercise and physical activity have been shown to be strongly associated with a decreased incidence rate of various chronic diseases especially numerous human malignancies. A huge number of clinical trials and meta-analysis have demonstrated that exercise is significantly effective in lowering the risk of colorectal cancer. In addition, it is suggested as an effective therapeutic modality against this cancer type. Therefore, in this review, we will review comprehensibly the effects of exercise in preventing, treating, and alleviating the adverse effects of conventional therapeutic options in colorectal cancer. Moreover, the possible mechanisms underlying the positive effects of exercise and physical activity in colorectal cancer, including regulation of inflammation, apoptosis, growth factor axis, immunity, epigenetic, etc. will be also discussed.

Exercise is an effective post-treatment management program in colorectal cancer survivals

Exercise improves muscle strength, cardiorespiratory fitness, emotional distress, physical activity, fatigue, and sleep quality in colorectal patients undergoing chemotherapy

Targeting and modulating insulin-like growth factor (IGF) system, inflammation, apoptosis, immunity, epigenetic, Leptin and Ghrelin, and signaling pathways are major underlying mechanisms for preventive effects of exercise in colorectal cancer

Association of sedentary work with colon and rectal cancer: systematic review and meta-analysis

OBJECTIVES

There has been no research on sedentary behaviour in the occupational domain that occupies a large portion of the daily life.

METHODS

We conducted a meta-analysis to investigate the association between sedentary work and colorectal cancer. We searched PubMed, Embase and Cochrane databases up to 12 August 2020 for peer-reviewed journal articles that assessed the association between sedentary work and colon or rectal cancer. Pooled estimates of ORs were obtained using random effects models. Statistical tests for publication bias, heterogeneity and sensitivity analysis were applied.

RESULTS

Of the 5 381 studies initially identified, 23 studies with 64 reports were eligible for inclusion. Sedentary work significantly increased the risk of colon cancer (pooled OR=1.21, 95% CI 1.11 to 1.31, p value ≤0.0001) and rectal cancer (pooled OR=1.08, 95% CI 1.00 to 1.16, p value=0.0395). The adjustment for leisure time physical activity attenuated the association and made the risk estimates non-significant for sedentary behaviour, but the association was independent of sex, control of body mass index and assessment of sedentary behaviour.

CONCLUSIONS

We found evidence of association between sedentary work and the risk of colon or rectal cancer. Limiting excessive sedentary work could be an important means of preventing colon and rectal cancer.

Physical activity and cancer risk. Actual knowledge and possible biological mechanisms

Background

Scientific evidence has shown that an increase in regular physical activity is associated with a decrease in the development of many types of cancer. Potential mechanisms that link physical activity to reduced cancer risk include a decrease in systemic inflammation, hyperinsulinemia, insulin-like growth factor (IGF-I), sex hormones, pro-inflammatory leptin and other obesity-related cytokines, and a significant increase in anti-inflammatory adiponectin levels. In addition, physical activity improves immune function and the composition and diversity of the gastrointestinal microbiota. Moderate physical activity is important for cancer protection, but the most significant changes in the inflammatory profile are conferred by physical activity performed at higher intensities. Thus, there is a need for further investigation into the type, intensity, and duration of physical activity for the prevention of some types of cancer and the development of effective recommendations.

Conclusions

There is a strong evidence that physical activity of moderate to vigorous intensity protects against colon and breast cancer, and probably against cancer at all other sites.

Association between physical activity and digestive-system cancer: An updated systematic review and meta-analysis

BACKGROUND

Physical activity (PA) may have an impact on digestive-system cancer (DSC) by improving insulin sensitivity and anticancer immune function and by reducing the exposure of the digestive tract to carcinogens by stimulating gastrointestinal motility, thus reducing transit time. The current study aimed to determine the effect of PA on different types of DSC via a systematic review and meta-analysis.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched for relevant studies in PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure. Using a random effects model, the relationship between PA and different types of DSC was analyzed.

RESULTS

The data used for meta-analysis were derived from 161 risk estimates in 47 studies involving 5,797,768 participants and 55,162 cases. We assessed the pooled associations between high vs. low PA levels and the risk of DSC (risk ratio (RR)  = 0.82, 95% confidence interval (95%CI): 0.79-0.85), colon cancer (RR = 0.81, 95%CI: 0.76-0.87), rectal cancer (RR = 0.88, 95%CI: 0.80-0.98), colorectal cancer (RR = 0.77, 95%CI: 0.69-0.85), gallbladder cancer (RR = 0.79, 95%CI: 0.64-0.98), gastric cancer (RR = 0.83, 95%CI: 0.76-0.91), liver cancer (RR = 0.73, 0.60-0.89), oropharyngeal cancer (RR = 0.79, 95%CI: 0.72-0.87), and pancreatic cancer (RR = 0.85, 95%CI: 0.78-0.93). The findings were comparable between case-control studies (RR = 0.73, 95%CI: 0.68-0.78) and prospective cohort studies (RR = 0.88, 95%CI: 0.80-0.91). The meta-analysis of 9 studies reporting low, moderate, and high PA levels, with 17 risk estimates, showed that compared to low PA, moderate PA may also reduce the risk of DSC (RR = 0.89, 95%CI: 0.80-1.00), while compared to moderate PA, high PA seemed to slightly increase the risk of DSC, although the results were not statistically significant (RR = 1.11, 95%CI: 0.94-1.32). In addition, limited evidence from 5 studies suggested that meeting the international PA guidelines might not significantly reduce the risk of DSC (RR = 0.96, 95%CI: 0.91-1.02).

CONCLUSION

Compared to previous research, this systematic review has provided more comprehensive information about the inverse relationship between PA and DSC risk. The updated evidence from the current meta-analysis indicates that a moderate-to-high PA level is a common protective factor that can significantly lower the overall risk of DSC. However, the reduction rate for specific cancers may vary. In addition, limited evidence suggests that meeting the international PA guidelines might not significantly reduce the risk of DSC. Thus, future studies must be conducted to determine the optimal dosage, frequency, intensity, and duration of PA required to reduce DSC risk effectively.

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.

Cancer Incidence by Occupation in Korea: Longitudinal Analysis of a Nationwide Cohort

Background

We performed this study to investigate the inequalities in site-specific cancer incidences among workers across different occupations in Korea.

Methods

Subjects included members of the national employment insurance. Incident cancers among 8,744,603 workers were followed from 1995 to 2007. Occupational groups were classified according to the Korean Standard Occupational Classification. Age-standardized incidence rate ratios were calculated.

Results

We found that men in service/sales and blue-collar occupations had elevated rates of esophageal, liver, laryngeal, and lung cancer. Among women, service/sales workers had elevated incidences of cervical cancer. Male prostate cancer, female breast, corpus uteri, and ovarian cancers, as well as male and female colorectal, kidney, and thyroid cancer showed lower incidences among workers in lower socioeconomic occupations.

Conclusions

Substantial differences in cancer incidences were found depending on occupation reflecting socioeconomic position, in the Korean working population. Cancer prevention policy should focus on addressing these socioeconomic inequalities.

Domain-specific physical activity and the risk of colorectal cancer: results from the Melbourne Collaborative Cohort Study

BACKGROUND

Physical activity reduces the risk of colorectal cancer (CRC), but the relevant evidence derives primarily from self-reported recreational and occupational activity. Less is known about the contribution of other domains of physical activity, such as transport and household. We examined associations between domain-specific physical activities and CRC risk within the Melbourne Collaborative Cohort Study.

METHODS

Analyses included 23,586 participants who were free from invasive colorectal cancer and had completed the International Physical Activity Questionnaire-Long Form at follow-up 2 (2003-2007). Cox regression, with age as the time metric, was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for ordinal categories of each physical activity domain.

RESULTS

Adjusted HRs for the highest versus the lowest categories of physical activity were 0.71 (95% CI: 0.51-0.98; ptrend = 0.03) for recreational activity; 0.80 (95% CI: 0.49-1.28; ptrend = 0.38) for occupational activity; 0.90 (95% CI: 0.68-1.19; ptrend = 0.20) for transport activity; and 1.07 (95% CI: 0.82-1.40; ptrend = 0.46) for household activity.

CONCLUSIONS

Recreational activity was associated with reduced CRC risk. A non-significant, inverse association was observed for occupational activity, whereas no association was found for transport or household domains.

Domain-specific physical activity and sedentary behaviour in relation to colon and rectal cancer risk: a systematic review and meta-analysis

Background

Physical activity is associated with reduced risk of colorectal cancer, but most epidemiological studies have focused on occupational and recreational physical activity. The evidence for other domains of activity, and for sedentary behaviour, is limited.

Methods

Medline, Embase and Web of Science were searched from inception to December 2015 for studies examining domain-specific physical activity or sedentary behaviour and the risk of colon and/or rectal cancer. We extracted maximally adjusted relative risks (RRs) except when RRs not adjusted for body mass index, were also presented. We used random-effects meta-analysis to compute pooled RRs comparing the highest versus the lowest level of exposure. We used meta-regression to assess sources of heterogeneity in estimates.

Results

We identified 17 cohort and 21 case-control studies, of which 17 had occupational data, 23 had recreational data, three each had data on transport and household physical activity domains, and 6 studies had data on occupational sedentary behaviour. The pooled relative risks (RRs) for colon cancer were 0.74 (95% confidence interval (CI): 0.67, 0.82) for occupational activity, 0.80 (95% CI: 0.71, 0.89) for recreational activity, 0.66 (95% CI: 0.45, 0.98) for transport-related physical activity, 0.85 (95% CI: 0.71, 1.02) for household physical activity, and 1.44 (95% CI: 1.28, 1.62) for occupational sedentary behaviour. For rectal cancer, the pooled RRs were 0.88 (95% CI: 0.79, 0.98) for occupational activity, 0.87 (95% CI: 0.75, 1.01) for recreational activity, 0.88 (95% CI: 0.70, 1.12) for transport-related physical activity, 1.01 (95% CI: 0.80, 1.27) for household physical activity, and 1.02 (95% CI: 0.82, 1.28) for occupational sedentary behaviour.

Conclusions

In addition to increasing occupational and recreational physical activity, promoting physical activity during transport and reducing sedentary behaviour in the workplace may also be useful colorectal cancer prevention strategies.

Association between shiftwork and the risk of colorectal cancer in females: a population-based case-control study

OBJECTIVE

Research indicates that shiftwork may be associated with increased risks of adverse health outcomes, including some cancers. However, the evidence of an association between shiftwork and colorectal cancer risk is limited and inconclusive. Further, while several possible pathways through which shiftwork might result in cancer have been proposed, few studies have taken these factors into account. We investigated the association between two types of shiftwork (graveyard shiftwork and early-morning shiftwork) and six mechanistic shiftwork variables (including light at night and phase shift) and the risk of colorectal cancer among females in an Australian population-based case-control study. Graveyard shiftwork was the primary exposure of interest.

METHODS

Participants (350 cases and 410 controls) completed a lifetime occupational history, and exposure to each of the eight shiftwork variables was assigned to participants through a job exposure matrix. We used logistic regression to calculate odds ratios (OR) and corresponding 95% confidence intervals (CI) for the association between different shiftwork variables and the risk of colorectal cancer, adjusting for potential demographic, lifestyle and medical confounders.

RESULTS

Working in an occupation involving long-term exposure (>7.5 years) to graveyard shiftwork was not associated with colorectal cancer risk (adjusted OR 0.95, 95% CI 0.57 to 1.58). Similarly, no increased risks of colorectal cancer were seen for any of the other seven shiftwork variables examined.

CONCLUSIONS

No evidence of an increased risk of colorectal cancer among females who had worked in occupations involving shiftwork was observed in this study.

Office-Cycling: A Promising Way to Raise Pain Thresholds and Increase Metabolism with Minimal Compromising of Work Performance

Aim

Establishing the effects of low intensity cycling (LC), moderate intensity cycling (MC), and standing at a simulated office workstation on pain modulation, work performance, and metabolic expenditure.

Methods

36 healthy adults (21 females), mean age 26.8 (SD 7.6) years, partook in this randomized 3 × 3 crossover trial with 75 minutes of LC on 20% of maximum aerobic power (MAP) output, 30 minutes of MC on 50% of MAP, and standing 30 minutes with 48-hour wash-out periods. Outcome measures were pain modulation (pressure pain threshold (PPT) and thermal pain threshold)), work performance (transcription, mouse pointing, and cognitive performance), and metabolic expenditure.

Results

PPTs increased in all conditions. PPT trapezius showed the highest increase after LC, 39.3 kilopascals (kPa) (15.6; 78.6), compared to MC, 17.0 kPa (2.8; 49.9), and standing, 16.8 kPa (-5.6; 39.4), p = 0.015. Transcription was reduced during LC and MC. Mouse pointing precision was best during standing and worst and slowest during MC. Cognitive performance did not differ between conditions. Metabolic expenditure rates were 1.4 (1.3; 1.7), 3.3 (2.3; 3.7), and 7.5 (5.8; 8.7) kcal/minute during standing, LC, and MC, respectively (p < 0.001).

Conclusions

LC seems to be the preferred option; it raised PPTs, more than doubled metabolic expenditure, whilst minimally influencing work performance.

Physical activity, sedentary behaviour, diet, and cancer: an update and emerging new evidence

The lifestyle factors of physical activity, sedentary behaviour, and diet are increasingly being studied for their associations with cancer. Physical activity is inversely associated with and sedentary behaviour is positively (and independently) associated with an increased risk of more than ten types of cancer, including colorectal cancer (and advanced adenomas), endometrial cancers, and breast cancer. The most consistent dietary risk factor for premalignant and invasive breast cancer is alcohol, whether consumed during early or late adult life, even at low levels. Epidemiological studies show that the inclusion of wholegrain, fibre, fruits, and vegetables within diets are associated with reduced cancer risk, with diet during early life (age <8 years) having the strongest apparent association with cancer incidence. However, randomised controlled trials of diet-related factors have not yet shown any conclusive associations between diet and cancer incidence. Obesity is a key contributory factor associated with cancer risk and mortality, including in dose-response associations in endometrial and post-menopausal breast cancer, and in degree and duration of fatty liver disease-related hepatocellular carcinoma. Obesity produces an inflammatory state, characterised by macrophages clustered around enlarged hypertrophied, dead, and dying adipocytes, forming crown-like structures. Increased concentrations of aromatase and interleukin 6 in inflamed breast tissue and an increased number of macrophages, compared with healthy tissue, are also observed in women with normal body mass index, suggesting a metabolic obesity state. Emerging randomised controlled trials of physical activity and dietary factors and mechanistic studies of immunity, inflammation, extracellular matrix mechanics, epigenetic or transcriptional regulation, protein translation, circadian disruption, and interactions of the multibiome with lifestyle factors will be crucial to advance this field.

Daily sedentary time and its association with risk for colorectal cancer in adults: A dose-response meta-analysis of prospective cohort studies

Sedentary behavior is emerging as an independent risk factor for health. However, previous studies have indicated that sedentary behaviors are associated with the colorectal cancer risk, but presented controversial results.Studies in PubMed and EMBASE were searched update to February 2017 to identify and quantify the potential dose-response association between daily sedentary time and colorectal cancer.Twenty-eight eligible studies involving a total of 47,84,339 participants with 46,071 incident cases were included in this meta-analysis. Our results showed statistically significant association between prolong television viewing time and colorectal cancer (odds ratio [OR] 1.17, 95% confidence interval [CI] 1.09-1.24, P < .001). Additionally, we obtained the best fit at an inflection point of 2 hours per day in piecewise regression analysis, the summary relative risk (RR) of colorectal cancer for an increase of 2 hours per day television viewing was 1.07 (95% CI 1.05-1.10, P < .001). Furthermore, prolong occupational sitting time was correlated with a significantly higher risk of colorectal cancer (OR 1.15, 95% CI 1.08-1.22, P < .001), increasing 2 hours per day of occupational sitting time per day was associated with a 4% incremental in the risk of colorectal cancer (RR 1.04, 95% CI 1.01-1.08). Additionally, prolong total sitting time was associated with a significantly higher risk of colorectal cancer (OR 1.06, 95% CI 1.03-1.09, P < .001). Increasing 2 hours of total sitting time per day was associated with a 2% incremental in the risk of colorectal cancer (RR 1.02, 95% CI 1.01-1.06). Subgroup meta-analyses in study design, study quality, number of participants, and number of cases showed consistent with the primary findings.Prolonged television viewing, occupational sitting time, and total sitting time are associated with increased risks of colorectal cancer.

Occupational exposure to carcinogens: Benzene, pesticides and fibers (Review)

It is well known that the occupational exposure to contaminants and carcinogens leads to the development of cancer in exposed workers. In the 18th century, Percivall Pott was the first to hypothesize that chronic exposure to dust in the London chimney sweeps was associated with an increased risk of developing cancer. Subsequently a growing body of evidence indicated that other physical factors were also responsible for oncogenic mutations. Over the past decades, many carcinogens have been found in the occupational environment and their presence is often associated with an increased incidence of cancer. Occupational exposure involves several factors and the association between carcinogens, occupational exposure and cancer is still unclear. Only a fraction of factors is recognized as occupational carcinogens and for each factor, there is an increased risk of cancer development associated with a specific work activity. According to the International Agency for Research on Cancer (IARC), the majority of carcinogens are classified as 'probable' and 'possible' human carcinogens, while, direct evidence of carcinogenicity is provided in epidemiological and experimental studies. In the present review, exposures to benzene, pesticides and mineral fibers are discussed as the most important cancer risk factors during work activities.

Lifestyle and Sporadic Colorectal Cancer in India

BACKGROUND

The study evaluated the patient, lifestyle and tumor profile in patients undergoing upfront surgery for sporadic colorectal cancer (CRC) in Indian population.

MATERIALS AND METHODS

One hundred consecutive patients were included. Details related to their demographic profile, habits, signs and symptoms, tumor profile, further treatment and follow up were recorded.

RESULTS

The majority of the patients had colonic cancer (68%), advanced tumor stage 3 and 4 (46%), moderately differentiated tumors (70%) with absence of lymphatic invasion (60%) and metastasis (90%). Correlations between tumor location and abdominal pain (p-value 0.002), bleeding per rectum (p-value <0.001), difficulty in micturition (p-value 0.012) and constipation (p-value 0.007) were found to be statistically significant. Abdominal pain was more frequently reported in patients with metastasis (p-value 0.031). Loss of weight statistically correlated with absence of lymphatic invasion (p-value 0.047). Associations between tumor stage and alcohol intake (p-value 0.050) and non vegetarian diet (p-value 0.006); lymphatic invasion and intake of spicy food (p-value 0.040) and non vegetarian diet (p-value 0.001) and metastasis and alcohol intake (p-value 0.041) were also observed. Age and tumor grade were also correlated (p-value 0.020).

CONCLUSIONS

Minimizing the adverse lifestyle factors can help in reducing the overall incidence of CRC in the Indian population.

Association between Adult Height and Risk of Colorectal, Lung, and Prostate Cancer: Results from Meta-analyses of Prospective Studies and Mendelian Randomization Analyses

BACKGROUND

Observational studies examining associations between adult height and risk of colorectal, prostate, and lung cancers have generated mixed results. We conducted meta-analyses using data from prospective cohort studies and further carried out Mendelian randomization analyses, using height-associated genetic variants identified in a genome-wide association study (GWAS), to evaluate the association of adult height with these cancers.

METHODS AND FINDINGS

A systematic review of prospective studies was conducted using the PubMed, Embase, and Web of Science databases. Using meta-analyses, results obtained from 62 studies were summarized for the association of a 10-cm increase in height with cancer risk. Mendelian randomization analyses were conducted using summary statistics obtained for 423 genetic variants identified from a recent GWAS of adult height and from a cancer genetics consortium study of multiple cancers that included 47,800 cases and 81,353 controls. For a 10-cm increase in height, the summary relative risks derived from the meta-analyses of prospective studies were 1.12 (95% CI 1.10, 1.15), 1.07 (95% CI 1.05, 1.10), and 1.06 (95% CI 1.02, 1.11) for colorectal, prostate, and lung cancers, respectively. Mendelian randomization analyses showed increased risks of colorectal (odds ratio [OR] = 1.58, 95% CI 1.14, 2.18) and lung cancer (OR = 1.10, 95% CI 1.00, 1.22) associated with each 10-cm increase in genetically predicted height. No association was observed for prostate cancer (OR = 1.03, 95% CI 0.92, 1.15). Our meta-analysis was limited to published studies. The sample size for the Mendelian randomization analysis of colorectal cancer was relatively small, thus affecting the precision of the point estimate.

CONCLUSIONS

Our study provides evidence for a potential causal association of adult height with the risk of colorectal and lung cancers and suggests that certain genetic factors and biological pathways affecting adult height may also affect the risk of these cancers.

Accelerometer-Measured Physical Activity and Sedentary Time Differ According to Education Level in Young Adults

This study examined the association of education level with objectively measured physical activity and sedentary time in young adults. Data from the Finnish ESTER study (2009–2011) (n = 538) was used to examine the association between educational attainment and different subcomponents of physical activity and sedentary time measured using hip-worn accelerometers (ActiGraph GT1M) for seven consecutive days. Overall physical activity, moderate-to-vigorous physical activity (MVPA), light-intensity physical activity and sedentary time were calculated separately for weekdays and weekend days. A latent profile analysis was conducted to identify the different profiles of sedentary time and the subcomponents of physical activity. The educational differences in accelerometer-measured physical activity and sedentary time varied according to the subcomponents of physical activity, and between weekdays and weekend days. A high education level was associated with high MVPA during weekdays and weekend days in both sexes, high sedentary time during weekdays in both sexes, and a low amount of light-intensity physical activity during weekdays in males and during weekdays and weekend days in females. The results indicate different challenges related to unhealthy behaviours in young adults with low and high education: low education is associated with a lack of MVPA, whereas high education is associated with a lack of light-intensity physical activity and high sedentary time especially during weekdays.

Physical Inactivity Is Associated with Moderate-Severe Obstructive Sleep Apnea

STUDY OBJECTIVE

To investigate whether low levels of physical activity were associated with an increased occurrence of obstructive sleep apnea (OSA), OSA-related symptoms, and cardiometabolic risk.

METHODS

A case-control study design was used. OSA cases were patients referred to a sleep clinic for suspected OSA (n = 2,340). Controls comprised participants from the Busselton community (n = 1,931). Exercise and occupational activity were derived from questionnaire data. Associations were modelled using logistic and linear regression and adjusted for confounders.

RESULTS

In comparison with moderate exercise, the high, low, and nil exercise groups had an odds ratio (OR) for moderate-severe OSA of 0.6 (95% CI 0.5-0.8), 1.6 (95% CI 1.2-2.0), and 2.7 (95% CI 1.9-3.7), respectively. Relative to men in heavy activity occupations, men in medium, light and sedentary occupations had an OR for moderate-severe OSA of 1.7 (95% CI 1.1-2.5), 2.1 (95% CI 1.4-3.2), and 1.8 (95% CI 1.2-2.8), respectively. Relative to women in medium activity occupations, women in light and sedentary occupations had an OR for moderate-severe OSA of 4.2 (95% CI 2.6-7.2) and 3.5 (2.0-6.0). OSA patients who adequately exercised had lower: levels of doctor-diagnosed depression (p = 0.047); symptoms of fatigue (p < 0.0001); systolic (p = 0.015) and diastolic blood pressure (p = 0.015); and C-reactive protein (CRP) (p = 0.003).

CONCLUSIONS

Low levels of physical activity were associated with moderate-severe OSA. Exercise in individuals with OSA is associated with lower levels of depression, fatigue, blood pressure and CRP.

Epigenetics and Colorectal Neoplasia: the Evidence for Physical Activity and Sedentary Behavior

Studies demonstrate that regular physical activity and, more recently, limited sedentary behavior are associated with reduced risk of colorectal neoplasia. However, the biological mechanisms of action for physical activity versus sedentary behavior are not clear. Epigenetic variation is suggested as a potential mechanism that would allow for independent, or possibly even synergistic, effects of activity and inactivity on colorectal epithelium. We describe the evidence for epigenetic variation as a link between physical activity and sedentary behavior in colorectal neoplasia risk. There are few studies that directly evaluate this relationship. However, the growing literature describes a variety of gene targets influenced by activity that are also important to colorectal neoplasia etiology. Future studies may identify epigenetic markers with translational significance in identifying high-risk individuals or those for whom a personalized activity regimen could significantly alter the methylation signature in colon epithelial cells, and thus future risk of colorectal cancer.

Step Counter Use and Sedentary Time in Adults: A Meta-Analysis

Although step counters are increasingly being used in walking programmes to promote sedentary behavior changes in adults, their effectiveness remains unknown. The aim of this meta-analysis of randomized controlled trials (RCTs) was to assess the effectiveness of step counter use in reducing sedentary time among adults.English-language RCTs from 3 databases were searched up to December 2014. Studies were included if they evaluated the effects of step counter use in adult populations and reported outcomes in sedentary time. Summary estimates (Cohen d with 95% confidence intervals [CIs]) were pooled using a random-effects model. Subgroup analyses and random-effects meta-regression analyses based on the characteristics of participants or interventions were conducted to explore their associations with sedentary time changes.Fifteen RCTs with a total sample size of 3262 adults were included. Step counter use was associated with a small but significant overall effect in reducing sedentary time (d = -0.20, 95% CI -0.33 to -0.07), equating to a reduction in sedentary time of ~23 min/d compared with controls. Subgroup analyses showed that step counter use with a step goal was associated with significantly reduced sedentary time (d =- 0.32, 95% CI -0.53 to -0.11), whereas without, it had only a trend. A greater reduction in sedentary time was observed among step counter users employing objective methods than those employing subjective methods for measurement (P = 0.03). Effects of covariates on sedentary time changes were generally unclear.Step counter use is associated with reduced sedentary time among adults. Future studies are required to specify the step goal use and to employ objective as well as subjective methods for measuring both total and domain-specific sedentary time.

Risk of Colorectal Cancer by Subsite in a Swedish Prostate Cancer Cohort

BACKGROUND

The relationship between sex hormone-related treatment for prostate cancer and the risk of colorectal cancer is controversial.

METHODS

A prostate cancer cohort was initiated from the Swedish Cancer Registry of patients diagnosed between 1961 and 2008. Patients diagnosed with prostate cancer between 1961 and 1980 were generally treated with estrogen. The cohort diagnosed between 1981 and 2008 was further divided into 3 subcohorts of orchiectomy, prostatectomy, and other treatment. Standardized incidence ratios (SIRs) for developing colorectal adenocarcinoma were estimated and 95% confidence intervals (CIs) were used to compare relative risk among these patients and the general male population.

RESULTS

Of 601,542 person-years of follow-up, 1,698 cases of colorectal adenocarcinoma were identified. Compared with the general male population, no association was detected in the cohort diagnosed between 1961 and 1980, whereas an increased risk of colorectal adenocarcinoma was observed among patients diagnosed with prostate cancer who received treatments other than estrogen. Following bilateral orchiectomy, the SIR was 1.30 (95% CI: 1.14-1.47); after prostatectomy, the SIR was 1.22 (95% CI: 1.04-1.43); among those who received treatment other than estrogen, the SIR was 1.37 (95% CI: 1.29-1.45). The increased risks were more apparent in cases of adenocarcinoma of the distal colon and rectum than in the proximal colon.

CONCLUSIONS

Patients with prostate cancer undergoing bilateral orchiectomy, prostatectomy, or other treatments, including antiandrogen therapy and radiation, may be at increased risk for colorectal adenocarcinoma.

Television watching and risk of colorectal adenoma

Background:

Prolonged TV watching, a major sedentary behaviour, is associated with increased risk of obesity and diabetes and may involve in colorectal carcinogenesis.

Methods:

We conducted a cross-sectional analysis among 31 065 men with ⩾1 endoscopy in the Health Professionals Follow-up Study (1988–2008) to evaluate sitting while watching TV and its joint influence with leisure-time physical activity on risk of colorectal adenoma. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

Results:

Prolonged sitting while watching TV was significantly associated with increased risk of colorectal adenoma (n=4280), and adjusting for physical activity or a potential mediator body mass index did not change the estimates. The ORs (95% CIs) across categories of TV watching (0–6, 7–13, 14–20, and 21+ h per week) were 1.00 (referent), 1.09 (1.01–1.17), 1.16 (1.06–1.27), and 1.10 (0.97–1.25) (OR per 14-h per week increment=1.11; 95% CI: 1.04–1.18; P_trend=0.001). Compared with the least sedentary (0–6 h per week of TV) and most physically active (highest quintile) men, the most sedentary (14+ h per week) and least active (lowest quintile) men had a significant increased risk of adenoma (OR=1.25; 95% CI: 1.05–1.49), particularly for high-risk adenoma.

Conclusions:

Prolonged TV viewing is associated with modest increased risk of colorectal adenoma independent of leisure-time physical activity and minimally mediated by obesity.

Rising incidence of early-onset colorectal cancer in Australia over two decades: report and review

The average age at diagnosis for colorectal cancer (CRC) in Australia is 69, and the age-specific incidence rises rapidly after age 50 years. The incidence has stabilized or is declining in older age groups in Australia during recent decades, possibly related to the increased uptake of screening and high-risk surveillance. In the same time frame, a rising incidence of CRC in younger adults has been well-documented in the United States. This rise in incidence in the young has not been reported from other countries that share long-term exposure to westernised urban lifestyles. Using data from the Australian Institute of Health and Welfare, we examined trends in national incidence rates for CRC under age 50 years and observed that rates in people under age 40 years have been rising for the last two decades. We further performed a review of the literature regarding CRC in young adults to outline the extent of current understanding, explore potential risk factors such as obesity, alcohol, and sedentary lifestyles, and to identify the questions remaining to be addressed. Although absolute numbers might not justify a population screening approach, the dispersal of young adults with CRC across the primary health-care system decreases probability of their recognition. Patient and physician awareness, aided by stool and emerging blood-screening tests and risk profiling tools, have the potential to aid in identification of those young adults who would most benefit from a colonoscopy through early detection of CRCs or by removal of advanced polyps.

Diagnostic value of rectal bleeding in predicting colorectal cancer: a systematic review

This study aimed at summarizing published study findings on the diagnostic value of rectal bleeding (RB) and informing clinical practice, preventive interventions and future research areas. We searched Medline and Embase for studies published by September 13, 2013 examining the risk of colorectal cancer in patients with RB using highly inclusive algorithms. Data for sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and positive predictive value (PPV) of RB were extracted by two researchers and analyzed applying Meta-Disc (version 1.4) and Stata (version 11.0). Methodological quality of studies was assessed according to QUADAS. A total of 38 studies containing 5,626 colorectal cancer patients and 73,174 participants with RB were included. The pooled sensitivity and specificity were 0.47 (95% CI: 0.45-0.48) and 0.96 (95% CI: 0.96-0.96) respectively. The overall PPVs ranged from 0.01 to 0.21 with a pooled value of 0.06 (95% CI: 0.05-0.08). Being over the age of 60 years, change in bowel habit, weight loss, anaemia, colorectal cancer among first-degree relatives and feeling of incomplete evacuation of rectum appeared to increase the predictive value of RB. Although RB greatly increases the probability of diagnosing colorectal cancer, it alone may not be sufficient for proposing further sophisticated investigations. However, given the high specificity, subjects without RB may be ruled out of further investigations. Future studies should focus on strategies using RB as an "alarm" symptom and finding additional indications to justify whether there is a need for further investigations.

Reducing occupational sedentary time: a systematic review and meta-analysis of evidence on activity-permissive workstations

Excessive sedentary time is detrimentally linked to obesity, type 2 diabetes, cardiovascular disease and premature mortality. Studies have been investigating the use of activity-permissive workstations to reduce sedentary time in office workers, a highly sedentary target group. This review systematically summarizes the evidence for activity-permissive workstations on sedentary time, health-risk biomarkers, work performance and feasibility indicators in office workplaces. In July 2013, a literature search identified 38 relevant peer-reviewed publications. Key findings were independently extracted by two researchers. The average intervention effect on sedentary time was calculated via meta-analysis. In total, 984 participants across 19 field-based trials and 19 laboratory investigations were included, with sample sizes ranging from n = 2 to 66 per study. Sedentary time, health-risk biomarkers and work performance indicators were reported in 13, 23 and 23 studies, respectively. The pooled effect size from the meta-analysis was -77 min of sedentary time/8-h workday (95% confidence interval = -120, -35 min). Non-significant changes were reported for most health- and work-related outcomes. Studies with acceptability measures reported predominantly positive feedback. Findings suggest that activity-permissive workstations can be effective to reduce occupational sedentary time, without compromising work performance. Larger and longer-term randomized-controlled trials are needed to understand the sustainability of the sedentary time reductions and their longer-term impacts on health- and work-related outcomes.

Sedentary behavior is associated with colorectal adenoma recurrence in men

PURPOSE

The association between physical activity and colorectal adenoma is equivocal. This study was designed to assess the relationship between physical activity and colorectal adenoma recurrence.

METHODS

Pooled analyses from two randomized, controlled trials included 1,730 participants who completed the Arizona Activity Frequency Questionnaire at baseline, had a colorectal adenoma removed within 6 months of study registration, and had a follow-up colonoscopy during the trial. Logistic regression modeling was employed to estimate the effect of sedentary behavior, light-intensity physical activity, and moderate-vigorous physical activity on colorectal adenoma recurrence.

RESULTS

No statistically significant trends were found for any activity type and odds of colorectal adenoma recurrence in the pooled population. However, males with the highest levels of sedentary time experienced 47% higher odds of adenoma recurrence. Compared to the lowest quartile of sedentary time, the ORs (95% CIs) for the second, third, and fourth quartiles among men were 1.23 (0.88, 1.74), 1.41 (0.99, 2.01), and 1.47 (1.03, 2.11), respectively (p(trend) = 0.03). No similar association was observed for women.

CONCLUSIONS

This study suggests that sedentary behavior is associated with a higher risk of colorectal adenoma recurrence among men, providing evidence of detrimental effects of a sedentary lifestyle early in the carcinogenesis pathway.

Television viewing and time spent sedentary in relation to cancer risk: a meta-analysis

BACKGROUND

Sedentary behavior is emerging as an independent risk factor for chronic disease and mortality. However, the evidence relating television (TV) viewing and other sedentary behaviors to cancer risk has not been quantitatively summarized.

METHODS

We performed a comprehensive electronic literature search in Cochrane, EMBASE, Medline, and SciSearch databases through February 2014 for published articles investigating sedentary behavior in relation to cancer incidence. Because randomized controlled trials are difficult to perform on this topic, we focused on observational studies that met uniform inclusion criteria. Data were extracted independently by both authors and summarized using random-effects meta-analysis and meta-regression. All statistical tests were two-sided.

RESULTS

Data from 43 observational studies including a total of 68936 cancer cases were analyzed. Comparing the highest vs lowest levels of sedentary time, the relative risks (RRs) for colon cancer were 1.54 (95% confidence interval [CI] = 1.19 to 1.98) for TV viewing time, 1.24 (95% CI = 1.09 to 1.41) for occupational sitting time, and 1.24 (95% CI = 1.03 to 1.50) for total sitting time. For endometrial cancer, the relative risks were 1.66 (95% CI = 1.21 to 2.28) for TV viewing time and 1.32 (95% CI = 1.08 to 1.61) for total sitting time. A positive association with overall sedentary behavior was also noted for lung cancer (RR = 1.21; 95% CI = 1.03 to 1.43). Sedentary behavior was unrelated to cancers of the breast, rectum, ovaries, prostate, stomach, esophagus, testes, renal cell, and non-Hodgkin lymphoma.

CONCLUSIONS

Prolonged TV viewing and time spent in other sedentary pursuits is associated with increased risks of certain types of cancer.

Discovery of colorectal cancer PIK3CA mutation as potential predictive biomarker: power and promise of molecular pathological epidemiology

Regular use of aspirin reduces incidence and mortality of various cancers, including colorectal cancer. Anticancer effect of aspirin represents one of the 'Provocative Questions' in cancer research. Experimental and clinical studies support a carcinogenic role for PTGS2 (cyclooxygenase-2), which is an important enzymatic mediator of inflammation, and a target of aspirin. Recent 'molecular pathological epidemiology' (MPE) research has shown that aspirin use is associated with better prognosis and clinical outcome in PIK3CA-mutated colorectal carcinoma, suggesting somatic PIK3CA mutation as a molecular biomarker that predicts response to aspirin therapy. The PI3K (phosphatidylinositol-4,5-bisphosphonate 3-kinase) enzyme has a pivotal role in the PI3K-AKT signaling pathway. Activating PIK3CA oncogene mutations are observed in various malignancies including breast cancer, ovarian cancer, brain tumor, hepatocellular carcinoma, lung cancer and colon cancer. The prevalence of PIK3CA mutations increases continuously from rectal to cecal cancers, supporting the 'colorectal continuum' paradigm, and an important interplay of gut microbiota and host immune/inflammatory reaction. MPE represents an interdisciplinary integrative science, conceptually defined as 'epidemiology of molecular heterogeneity of disease'. As exposome and interactome vary from person to person and influence disease process, each disease process is unique (the unique disease principle). Therefore, MPE concept and paradigm can extend to non-neoplastic diseases including diabetes mellitus, cardiovascular diseases, metabolic diseases, and so on. MPE research opportunities are currently limited by paucity of tumor molecular data in the existing large-scale population-based studies. However, genomic, epigenomic and molecular pathology testings (for example, analyses for microsatellite instability, MLH1 promoter CpG island methylation, and KRAS and BRAF mutations in colorectal tumors) are becoming routine clinical practices. In order for integrative molecular and population science to be routine practice, we must first reform education curricula by integrating both population and molecular biological sciences. As consequences, next-generation hybrid molecular biological and population scientists can advance science, moving closer to personalized precision medicine and health care.

Association of sedentary behaviour with colon and rectal cancer: a meta-analysis of observational studies

BACKGROUND

Sedentary behaviour is ubiquitous in modern society. Emerging studies have focused on the health consequences of sedentary behaviour, including colorectal cancer, but whether sedentary behaviour is associated with the risks of colon and rectal cancer remains unclear. No systematic reviews have applied quantitative techniques to independently compute summary risk estimates. We aimed to conduct a meta-analysis to investigate this issue.

METHODS

We searched PubMed, Embase, and Google Scholar databases up to May 2013 to identify cohort and case-control studies that evaluated the association between sedentary behaviour and colon or rectal cancer. A random-effect model was used to pool the results of included studies. Publication bias was assessed by using Begg's funnel plot.

RESULTS

Twenty-three studies with 63 reports were included in our meta-analysis. These groups included 4,324,462 participants (27,231 colon cancer cases and 13,813 rectal cancer cases). Sedentary behaviour was significantly associated with colon cancer (relative risk (RR): 1.30, 95% confidence interval (CI): 1.22-1.39) but did not have a statistically significant association with rectal cancer (RR 1.05, 95% CI, 0.98-1.13). Subgroup analyses suggested that the odds ratio (OR) of colon cancer was 1.46 (95% CI: 1.22-1.68) in the case-control studies, and the RR was 1.27 (95% CI: 1.18-1.36) in the cohort studies, the OR of rectal cancer was 1.06 (95% CI: 0.85-1.33) in the case-control studies, and the RR was 1.06 (95% CI, 1.01-1.12) in the cohort studies.

CONCLUSION

Sedentary behaviour is associated with an increased risk of colon cancer. Subgroup analyses suggest a positive association between sedentary behaviour and risk of rectal cancer in cohort studies. Reducing sedentary behaviour is potentially important for the prevention of colorectal cancer.

Lifestyle factors associated with survival after colorectal cancer diagnosis

Background:

Aside from tumour stage and treatment, little is known about potential factors that may influence survival in colorectal cancer patients. The aim of this study was to investigate the associations between physical activity, obesity and smoking and disease-specific and overall mortality after a colorectal cancer diagnosis.

Methods:

A cohort of 879 colorectal cancer patients, diagnosed in Western Australia between 2005 and 2007, were followed up to 30 June 2012. Cox's regression models were used to estimate the hazard ratios (HR) for colorectal cancer-specific and overall mortality associated with self-reported pre-diagnosis physical activity, body mass index (BMI) and smoking.

Results:

Significantly lower overall and colorectal cancer-specific mortality was seen in females who reported any level of recent physical activity than in females reporting no activity. The colorectal cancer-specific mortality HR for increasing levels of physical activity in females were 0.34 (95% CI=0.15, 0.75), 0.37 (95% CI=0.17, 0.81) and 0.41 (95% CI=0.18, 0.90). Overweight and obese women had almost twice the risk of dying from any cause or colorectal cancer compared with women of normal weight. Females who were current smokers had worse overall and colorectal cancer-specific mortality than never smokers (overall HR=2.64, 95% CI=1.18, 5.93; colorectal cancer-specific HR=2.70, 95% CI=1.16, 6.29). No significant associations were found in males.

Conclusion:

Physical activity, BMI and smoking may influence survival after a diagnosis of colorectal cancer, with more pronounced results found for females than for males.

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.

Molecular pathological epidemiology of epigenetics: emerging integrative science to analyze environment, host, and disease

Epigenetics acts as an interface between environmental/exogenous factors, cellular responses, and pathological processes. Aberrant epigenetic signatures are a hallmark of complex multifactorial diseases (including neoplasms and malignancies such as leukemias, lymphomas, sarcomas, and breast, lung, prostate, liver, and colorectal cancers). Epigenetic signatures (DNA methylation, mRNA and microRNA expression, etc) may serve as biomarkers for risk stratification, early detection, and disease classification, as well as targets for therapy and chemoprevention. In particular, DNA methylation assays are widely applied to formalin-fixed, paraffin-embedded archival tissue specimens as clinical pathology tests. To better understand the interplay between etiological factors, cellular molecular characteristics, and disease evolution, the field of 'molecular pathological epidemiology (MPE)' has emerged as an interdisciplinary integration of 'molecular pathology' and 'epidemiology'. In contrast to traditional epidemiological research including genome-wide association studies (GWAS), MPE is founded on the unique disease principle, that is, each disease process results from unique profiles of exposomes, epigenomes, transcriptomes, proteomes, metabolomes, microbiomes, and interactomes in relation to the macroenvironment and tissue microenvironment. MPE may represent a logical evolution of GWAS, termed 'GWAS-MPE approach'. Although epigenome-wide association study attracts increasing attention, currently, it has a fundamental problem in that each cell within one individual has a unique, time-varying epigenome. Having a similar conceptual framework to systems biology, the holistic MPE approach enables us to link potential etiological factors to specific molecular pathology, and gain novel pathogenic insights on causality. The widespread application of epigenome (eg, methylome) analyses will enhance our understanding of disease heterogeneity, epigenotypes (CpG island methylator phenotype, LINE-1 (long interspersed nucleotide element-1; also called long interspersed nuclear element-1; long interspersed element-1; L1) hypomethylation, etc), and host-disease interactions. In this article, we illustrate increasing contribution of modern pathology to broader public health sciences, which attests pivotal roles of pathologists in the new integrated MPE science towards our ultimate goal of personalized medicine and prevention.

Prospective analysis of body mass index, physical activity, and colorectal cancer risk associated with β-catenin (CTNNB1) status

Dysregulation of the WNT/β-catenin (CTNNB1) signaling pathway is implicated in colorectal carcinoma and metabolic diseases. Considering these roles and cancer prevention, we hypothesized that tumor CTNNB1 status might influence cellular sensitivity to obesity and physical activity. In clinical follow-up of 109,046 women in the Nurses' Health Study and 47,684 men in the Health Professionals Follow-up Study, there were 861 incident rectal and colon cancers with tissue immunohistochemistry data on nuclear CTNNB1 expression. Using this molecular pathological epidemiology database, we conducted Cox proportional hazards regression analysis using data duplication method to assess differential associations of body mass index (BMI) or exercise activity with colorectal cancer risk according to tumor CTNNB1 status. Greater BMI was associated with a significantly higher risk of CTNNB1-negative cancer [multivariate HR = 1.34; 95% confidence interval (CI), 1.18-1.53 for 5.0 kg/m(2) increment; Ptrend = 0.0001] but not with CTNNB1-positive cancer risk (multivariate HR = 1.07; 95% CI, 0.92-1.25 for 5.0 kg/m(2) increment; Ptrend = 0.36; Pheterogeneity = 0.027, between CTNNB1-negative and CTNNB1-positive cancer risks). Physical activity level was associated with a lower risk of CTNNB1-negative cancer (multivariate HR = 0.93; 95% CI, 0.87-1.00 for 10 MET-h/wk increment; Ptrend = 0.044) but not with CTNNB1-positive cancer risk (multivariate HR = 0.98; 95% CI, 0.91-1.05 for 10 MET-h/wk increment; Ptrend = 0.60). Our findings argue that obesity and physical inactivity are associated with a higher risk of CTNNB1-negative colorectal cancer but not with CTNNB1-positive cancer risk. Furthermore, they suggest that energy balance and metabolism status exerts its effect in a specific carcinogenesis pathway that is less likely dependent on WNT/CTNNB1 activation. Cancer Res; 73(5); 1600-10. ©2012 AACR.

The role of physical activity in primary cancer prevention

Few modifiable lifestyle factors have been shown to be associated with reduced cancer risk. For physical activity, more than 200 epidemiologic studies have provided evidence that its association with cancer risk is convincing for colon and breast cancers; probable for endometrial cancer; possible for prostate, gastric, and ovarian cancers; and insufficient for all other cancer sites. Relative risk reductions are in the range of 10–30 %. On the absolute scale, about 9–19 % of the most frequent cancers can be attributed to a lack of sufficient physical activity. As modifiable health behavior, exercise thus has a strong potential for primary cancer prevention and the evidence is sufficiently established to recommend physical activity as a means for the primary prevention of cancer. Current recommendations call for at least 30–60 min of moderate to vigorous activity daily. However, further research is needed to provide a stronger evidence base specifically for these recommendations. The exact type, dose, and timing of physical activity remain unclear but ongoing and planned research will elucidate these associations. In addition, possible biologic mechanisms whereby physical activity may influence carcinogenesis, independently and/or jointly with other factors of the energy balance equation, need further attention in future research.

How many molecular subtypes? Implications of the unique tumor principle in personalized medicine

Cancers are complex multifactorial diseases. For centuries, conventional organ-based classification system (i.e., breast cancer, lung cancer, colon cancer, colorectal cancer, prostate cancer, lymphoma, leukemia, and so on) has been utilized. Recently, molecular diagnostics has become an essential component in clinical decision-making. However, tumor evolution and behavior cannot accurately be predicted, despite numerous research studies reporting promising tumor biomarkers. To advance molecular diagnostics, a better understanding of intratumor and intertumor heterogeneity is essential. Tumor cells interact with the extracellular matrix and host non-neoplastic cells in the tumor microenvironment, which is influenced by genomic variation, hormones, and dietary, lifestyle and environmental exposures, implicated by molecular pathological epidemiology. Essentially, each tumor possesses its own unique characteristics in terms of molecular make-up, tumor microenvironment and interactomes within and between neoplastic and host cells. Starting from the unique tumor concept and paradigm, we can better classify tumors by molecular methods, and move closer toward personalized cancer medicine and prevention.

Interdisciplinary education to integrate pathology and epidemiology: towards molecular and population-level health science

In recent decades, epidemiology, public health, and medical sciences have been increasingly compartmentalized into narrower disciplines. The authors recognize the value of integration of divergent scientific fields in order to create new methods, concepts, paradigms, and knowledge. Herein they describe the recent emergence of molecular pathological epidemiology (MPE), which represents an integration of population and molecular biologic science to gain insights into the etiologies, pathogenesis, evolution, and outcomes of complex multifactorial diseases. Most human diseases, including common cancers (such as breast, lung, prostate, and colorectal cancers, leukemia, and lymphoma) and other chronic diseases (such as diabetes mellitus, cardiovascular diseases, hypertension, autoimmune diseases, psychiatric diseases, and some infectious diseases), are caused by alterations in the genome, epigenome, transcriptome, proteome, metabolome, microbiome, and interactome of all of the above components. In this era of personalized medicine and personalized prevention, we need integrated science (such as MPE) which can decipher diseases at the molecular, genetic, cellular, and population levels simultaneously. The authors believe that convergence and integration of multiple disciplines should be commonplace in research and education. We need to be open-minded and flexible in designing integrated education curricula and training programs for future students, clinicians, practitioners, and investigators.

Methylation of the polycomb group target genes is a possible biomarker for favorable prognosis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the second most common cancer in the Kingdom of Saudi Arabia with ever increasing incidence rates. DNA methylation is a common event in CRC where it is now considered an important phenomenon in CRC carcinogenesis and useful for the classification and prognosis of CRC.

METHODS

To gain insight into the molecular mechanisms underpinning CRC in Saudi Arabian patients, we profiled the DNA methylation frequency of key genes (MLH1, MSH2, RASSF1A, SLIT2, HIC1, MGMT, SFRP1, MYOD1, APC, CDKN2A, as well as five CIMP markers) in 120 sporadic CRC cases. CRC tumors originating from the rectum, left, and right colons are represented in this cohort of formalin-fixed paraffin-embedded tissues.

RESULTS

The most common methylation frequency was detected in the polycomb group target genes (PCGT) including SFRP1 (70%), MYOD1 (60.8%), HIC1 (61.7%), and SLIT2 (56.7%). In addition, MGMT methylation was detected at a high frequency (68.3%). RASSF1A, APC, and CDKN2A methylation frequencies were 42.5%, 25%, and 32.8%, respectively. K-means clustering analysis of the methylation events results in the clustering of the CRC samples into three groups depending on the level of methylation detected.

CONCLUSION

Group II (PCGT methylation and CIMP-negative) methylation signature carried a favorable prognosis for male patients, whereas older patients with group I rare methylation signature have a potentially poorer clinical outcome.

IMPACT

Methylation of the PCGT genes along with RASSF1A, APC, and MGMT can be potentially used as a new biomarker for the classification and prognosis of CRC tumors and independently of where the tumor has originated.

Interdisciplinary education to integrate pathology and epidemiology: towards molecular and population-level health science

In recent decades, epidemiology, public health, and medical sciences have been increasingly compartmentalized into narrower disciplines. The authors recognize the value of integration of divergent scientific fields in order to create new methods, concepts, paradigms, and knowledge. Herein they describe the recent emergence of molecular pathological epidemiology (MPE), which represents an integration of population and molecular biologic science to gain insights into the etiologies, pathogenesis, evolution, and outcomes of complex multifactorial diseases. Most human diseases, including common cancers (such as breast, lung, prostate, and colorectal cancers, leukemia, and lymphoma) and other chronic diseases (such as diabetes mellitus, cardiovascular diseases, hypertension, autoimmune diseases, psychiatric diseases, and some infectious diseases), are caused by alterations in the genome, epigenome, transcriptome, proteome, metabolome, microbiome, and interactome of all of the above components. In this era of personalized medicine and personalized prevention, we need integrated science (such as MPE) which can decipher diseases at the molecular, genetic, cellular, and population levels simultaneously. The authors believe that convergence and integration of multiple disciplines should be commonplace in research and education. We need to be open-minded and flexible in designing integrated education curricula and training programs for future students, clinicians, practitioners, and investigators.

Physical activity and risks of proximal and distal colon cancers: a systematic review and meta-analysis

BACKGROUND

Although there is convincing epidemiological evidence that physical activity is associated with a reduced risk of colon cancer, it is unclear whether physical activity is differentially associated with the risks of proximal colon and distal colon cancers. We conducted a systematic review and meta-analysis to investigate this issue.

METHODS

MEDLINE and EMBASE were searched for English-language cohort and case-control studies that examined associations between physical activity and the risks of proximal colon and distal colon cancers. A random-effects meta-analysis was conducted to estimate the summary relative risks (RRs) for the associations between physical activity and the risks of the two cancers. All statistical tests were two-sided.

RESULTS

A total of 21 studies met the inclusion criteria. The summary relative risk of the main results from these studies indicated that the risk of proximal colon cancer was 27% lower among the most physically active people compared with the least active people (RR = 0.73, 95% confidence interval [CI] = 0.66 to 0.81). An almost identical result was found for distal colon cancer (RR = 0.74, 95% CI = 0.68 to 0.80).

CONCLUSION

The results of this systematic review and meta-analysis suggest that physical activity is associated with a reduced risk of both proximal colon and distal colon cancers, and that the magnitude of the association does not differ by subsite. Given this finding, future research on physical activity and colon cancer should focus on other aspects of the association that remain unclear, such as whether sedentary behavior and nonaerobic physical activity are associated with the risk of colon cancer.

Caffeinated and decaffeinated coffee and tea intakes and risk of colorectal cancer in a large prospective study

BACKGROUND

Coffee and tea are widely consumed globally and are rich sources of potential chemopreventive compounds. Epidemiologic data for coffee and tea intakes in relation to colorectal cancer remain unclear. Despite differences in gut physiology, few studies have conducted investigations by anatomic subsites.

OBJECTIVE

We evaluated coffee and tea intakes (caffeinated and decaffeinated) in relation to colon (proximal and distal) and rectal cancers.

DESIGN

The NIH-AARP Diet and Health Study included 489,706 men and women who completed a baseline (1995-1996) self-administered questionnaire of demographics, diet, and lifestyle. Over a median of 10.5 y of follow-up, we identified 2863 proximal colon, 1993 distal colon, and 1874 rectal cancers. Multivariable HRs and 95% CIs were estimated by using Cox regression.

RESULTS

Approximately 16% of participants drank ≥4 cups coffee/d. Compared with nondrinkers, drinkers of 4-5 cups coffee/d (HR: 0.85; 95% CI: 0.75, 0.96) and ≥6 cups coffee/d (HR: 0.74; 95% CI: 0.61, 0.89; P-trend < 0.001) had a lower risk of colon cancer, particularly of proximal tumors (HR for ≥6 cups/d: 0.62; 95% CI: 0.49, 0.81; P-trend < 0.0001). Results were similar to those overall for drinkers of predominantly caffeinated coffee. Although individual HRs were not significant, there was a significant P-trend for both colon and rectal cancers for people who drank predominantly decaffeinated coffee. No associations were observed for tea.

CONCLUSIONS

In this large US cohort, coffee was inversely associated with colon cancer, particularly proximal tumors. Additional investigations of coffee intake and its components in the prevention of colorectal cancer by subsites are warranted. The NIH-AARP Diet and Health Study was registered at clinicaltrials.gov as NCT00340015.