Dietary Factors and Early-Onset Colorectal Cancer in the United States-an Ecologic Analysis

Risk factors for early-onset colorectal cancer: A Canadian prospective cohort study

PURPOSE

The incidence of early-onset (<50 years of age) colorectal cancer (eoCRC) has been steadily increasing in high-income countries including Canada. Despite this increase in incidence, the etiology of eoCRC remains unclear and prospective cohort studies of potential risk factors are limited.

METHODS

We examined two prospective cohorts of healthy individuals (<50 years of age) who completed baseline questionnaires in the Ontario Health Study and Alberta's Tomorrow Project. We examined the associations between demographic characteristics, chronic health conditions, and lifestyle behaviours with the development of eoCRC using Cox proportional hazard models. Cohorts were analyzed separately and hazard ratios for each risk factor were pooled with random effects meta-analyses.

RESULTS

During an average follow-up of 6.63 years, 98 eoCRC cases occurred among study participants (n=127,852). A family history of CRC alone or with a history of other cancer types was associated with an increased risk of developing eoCRC (HR: 2.76, 95% CI: 1.43-5.32), but a family history of a non-CRC cancer only was not (HR: 1.18, 95% CI: 0.61-2.30). Heavy smokers (≥ 10 pack-years) at baseline had a higher risk of eoCRC compared to non-smokers (HR: 1.87, 95% CI: 1.00-3.52). Sex, socioeconomic factors, diabetes, alcohol consumption, among other factors were not significantly associated with the risk of eoCRC.

CONCLUSION

Our findings indicate that specific CRC risk factors are also associated with developing eoCRC. The data in the study offers valuable insights that could be integrated in future meta-analyses. Additional prospective cohort studies are required to understand the etiology of eoCRC.

Comparing cohort and period trends of early-onset colorectal cancer: a global analysis

BACKGROUND

Incidence of early-onset colorectal cancer (CRC) has increased globally in recent decades. We examined early-onset CRC incidence trends worldwide for potential cohort effects, defined as changes associated with time of birth (eg, early-life exposure to carcinogens), and period effects, defined as changes associated with calendar periods (eg, screening programs).

METHODS

We obtained long-term incidence data for early-onset CRC diagnosed in patients aged 20 to 49 years through the year 2012 for 35 countries in the Cancer Incidence in Five Continents database. We used a smoothing method to help compare cohort and period trends of early-onset CRC and used an age-period-cohort model to estimate cohort and period effects.

RESULTS

Cohort effects had a more dominant role than period effects in the early-onset CRC incidence in Shanghai (China), the United Kingdom, Australia, New Zealand, Canada, the United States, and Osaka (Japan). The smoothed trends show the specific birth cohorts when early-onset CRC began to increase: the 1940s-1950s birth cohorts in the United States; the 1950s-1960s birth cohorts in other Western countries; the 1960s birth cohorts in Osaka; and the 1970s-1980s birth cohorts in Shanghai. Such increases occurred earlier for early-onset cancers of the rectum than of the colon. For the other countries, the results were less clear.

CONCLUSIONS

Recent birth cohorts may have been exposed to risk factors different from earlier cohorts, contributing to increased early-onset CRC incidence in several developed countries or regions in the West and Asia. Such increases began in earlier birth cohorts in Western countries than in developed regions of Asia.

Environmental drivers of the rising incidence of early-onset colorectal cancer in the United States

Incidence of early-onset (diagnosed before age 50) colorectal cancer (EOCRC) has increased alarmingly since the 1990s in the United States. This study investigated what environmental exposures may have driven this increase. We obtained EOCRC incidence data from the Surveillance, Epidemiology, and End Results Program, and data for 11 exposures, for example, body mass index (BMI), from long-term national surveys. We aggregated these data for 30 to 49-year-olds during 1992 to 2016 by population subgroups defined by calendar period, age, race and sex, and used negative binomial regression models to identify and estimate associations of EOCRC with multiple exposures. Furthermore, we used counterfactual modeling to quantify contributions of identified risk factors to EOCRC incidence. The top models (with lowest Bayesian Information Criteria) consistently identified excess body weight, represented by overweight and obesity (BMI ≥25) or obesity alone (BMI ≥30), as the strongest risk factor. The best-performing model estimated increased EOCRC incidence due to overweight and obesity, with an incidence rate ratio (95% confidence interval) of 1.20 (1.17-1.22) for white men, 1.04 (1.00-1.08) for black men, 1.17 (1.15-1.21) for white women and 1.03 (0.97-1.08) for black women. Increases in overweight and obesity prevalence contributed to an estimated 30% (standard error: 1%) for men and 28% (standard error: 2%) for women of ECORC incidence during 1992 to 2016. These findings suggest excess body weight substantially contributed to and is likely a primary driver of the rising incidence of EOCRC in the United States. Prevention of excess weight gain may help lower colorectal cancer risk early in life.

Cancer incidence trends in New York State and associations with common population-level exposures 2010-2018: an ecological study

The impact of common environmental exposures in combinations with socioeconomic and lifestyle factors on cancer development, particularly for young adults, remains understudied. Here, we leveraged environmental and cancer incidence data collected in New York State at the county level to examine the association between 31 exposures and 10 common cancers (i.e., lung and bronchus, thyroid, colorectal, kidney and renal pelvis, melanoma, non-Hodgkin lymphoma, and leukemia for both sexes; corpus uteri and female breast cancer; prostate cancer), for three age groups (25-49, 50-69, and 70-84 year-olds). For each cancer, we stratified by age group and sex, and applied regression models to examine the associations with multiple exposures simultaneously. The models included 642,013 incident cancer cases during 2010-2018 and found risk factors consistent with previous reports (e.g., smoking and physical inactivity). Models also found positive associations between ambient air pollutants (ozone and PM2.5) and prostate cancer, female breast cancer, and melanoma of the skin across multiple population strata. Additionally, the models were able to better explain the variation in cancer incidence data among 25-49 year-olds than the two older age groups. These findings support the impact of common environmental exposures on cancer development, particularly for younger age groups.

Early-onset gastrointestinal cancer: An epidemiological reality with great significance and implications

During the last few years, epidemiological data from many countries suggest that the incidence and prevalence of many cancers of the digestive system are shifting from the older to the younger ages, the so-called "early-onset cancer". This is particularly evident in colorectal cancer and secondarily in other malignant digestive neoplasms, mainly stomach and in a lesser degree pancreas, and biliary tract. It should be emphasized that data concerning digestive neoplasms, except for those referring to the colon and stomach, could be characterized as rather insufficient. The exact magnitude of the shift in younger ages is expected to become clearer shortly, as long as relevant epidemiological data from many parts of the world would be available. The most important question concerns the etiology of this phenomenon, since its magnitude cannot be explained solely by the better diagnostic methodology and the preventive programs applied in many countries. The existing data support the assumption that a number of environmental factors may play a primary role in influencing carcinogenesis, sometimes from childhood. Changes that have appeared in the last decades related mainly to eating habits, consistency of gut microbiome and an increase of obese people interacting with genetic factors, ultimately favor the process of carcinogenesis. Even these factors however, are not entirely sufficient to explain the age-related changes in the frequency of digestive neoplasms. Studies of the individual effect of each of the already known factors or factors likely to be involved in the etiology of this phenomenon and studies using state-of-the-art technologies to accurately determine the degree of the population exposure to these factors are required. In this article, we attempt to describe the epidemiological data supporting the age-shifting of digestive malignancies and their possible pathogenesis. Finally, we propose some measures regarding the attitude of the scientific community to this alarming phenomenon.

Pharmaceutical Agents as Potential Drivers in the Development of Early-Onset Colorectal Cancer: Case-Control Study

BACKGROUND

The incidence of early-onset colorectal cancer (EOCRC) rose abruptly in the mid 1990s, is continuing to increase, and has now been noted in many countries. By 2030, 25% of American patients diagnosed with rectal cancer will be 49 years or younger. The large majority of EOCRC cases are not found in patients with germline cancer susceptibility mutations (eg, Lynch syndrome) or inflammatory bowel disease. Thus, environmental or lifestyle factors are suspected drivers. Obesity, sedentary lifestyle, diabetes mellitus, smoking, alcohol, or antibiotics affecting the gut microbiome have been proposed. However, these factors, which have been present since the 1950s, have not yet been conclusively linked to the abrupt increase in EOCRC. The sharp increase suggests the introduction of a new risk factor for young people. We hypothesized that the driver may be an off-target effect of a pharmaceutical agent (ie, one requiring regulatory approval before its use in the general population or an off-label use of a previously approved agent) in a genetically susceptible subgroup of young adults. If a pharmaceutical agent is an EOCRC driving factor, regulatory risk mitigation strategies could be used.

OBJECTIVE

We aimed to evaluate the possibility that pharmaceutical agents serve as risk factors for EOCRC.

METHODS

We conducted a case-control study. Data including demographics, comorbidities, and complete medication dispensing history were obtained from the electronic medical records database of Maccabi Healthcare Services, a state-mandated health provider covering 26% of the Israeli population. The participants included 941 patients with EOCRC (≤50 years of age) diagnosed during 2001-2019 who were density matched at a ratio of 1:10 with 9410 control patients. Patients with inflammatory bowel disease and those with a known inherited cancer susceptibility syndrome were excluded. An advanced machine learning algorithm based on gradient boosted decision trees coupled with Bayesian model optimization and repeated data sampling was used to sort through the very high-dimensional drug dispensing data to identify specific medication groups that were consistently linked with EOCRC while allowing for synergistic or antagonistic interactions between medications. Odds ratios for the identified medication classes were obtained from a conditional logistic regression model.

RESULTS

Out of more than 800 medication classes, we identified several classes that were consistently associated with EOCRC risk across independently trained models. Interactions between medication groups did not seem to substantially affect the risk. In our analysis, drug groups that were consistently positively associated with EOCRC included beta blockers and valerian (Valeriana officinalis). Antibiotics were not consistently associated with EOCRC risk.

CONCLUSIONS

Our analysis suggests that the development of EOCRC may be correlated with prior use of specific medications. Additional analyses should be used to validate the results. The mechanism of action inducing EOCRC by candidate pharmaceutical agents will then need to be determined.

Elucidating the Drivers for the Rising Incidence of Early-Onset Colorectal Cancer: How Ecologic Studies Could Help and What Is Next

The incidence of colorectal cancer diagnosed before age 50, often referred to as early-onset colorectal cancer, has been increasing, whereas the overall colorectal cancer incidence has declined. Elucidating the drivers for the rising burden of early-onset colorectal cancer is a priority in cancer epidemiology and prevention. In this issue of Cancer Epidemiology, Biomarkers & Prevention, Chen and colleagues demonstrated that ecologic studies are a helpful method to reveal emerging risk factors at the population level and concluded that alcohol use might be a potential contributor to the rising incidence of early-onset colorectal cancer. Moving forward, because of the observed birth cohort effect in early-onset colorectal cancer, where younger generations have a steeper increase, hypothesis-driven investigations on emerging risk factors in recent generations, especially during early life, are warranted. Ultimately, the identified risk factors could be integrated with well-established microsimulation models of colorectal cancer, powerful tools that can simultaneously capture population-level secular changes in risk factors, relative risk estimates for each risk factor, and the natural history of colorectal cancer. This would allow us to quantitatively estimate the explained and unexplained portion of the rising incidence of early-onset colorectal cancer by calendar period and birth cohorts, and to help identify priorities in etiologic research, prevention, and early detection. See related article by Chen et al., p. 217.