Use of non-steroidal anti-inflammatory drugs and pancreatic cancer risk in the Women's Health Initiative.

BACKGROUND: Pancreatic cancer is among the most fatal human cancers and the fourth leading cause of cancer death in the United States. Evidence suggests that chronic inflammation may play a role in pancreatic carcinogenesis, and its inhibition through non-steroidal anti-inflammatory drugs (NSAIDs) may reduce pancreatic cancer incidence. METHODS: We examined associations of total and individual NSAIDs with pancreatic cancer risk among postmenopausal women participating in the Women's Health Initiative observational study and clinical trials cohorts. Among 117,452 women, ages 55-79 years, 727 incident pancreatic cancer cases were reported over 18 years of follow-up. Cox regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations between NSAIDs and pancreatic cancer risk. RESULTS: Relative to non-use, consistent use of any NSAID was inversely associated with pancreatic cancer risk (HR 0.71, 95% CI: 0.59-0.87), primarily driven by strong associations for aspirin use (HR 0.67, 95% CI: 0.52-0.86). Use of total or individual non-aspirin NSAIDs were not associated with pancreatic cancer. Upon stratified analysis, we observed stronger associations for NSAIDs among participants with prevalent diabetes (HR 0.28, 95% CI: 0.10-0.75) relative to those without (HR 0.75, 95% CI: 0.61-0.92; P-interaction=0.03). CONCLUSIONS: Additional large prospective studies with careful measurement of NSAID type, dose, and frequency are needed to further investigate the possibility of added benefit among individuals diagnosed with diabetes. IMPACT: This study adds to existing evidence from prospective studies and clinical trials suggesting that use of aspirin may provide moderate benefit for pancreatic cancer prevention.

The utility of liquid biopsy-based methylation biomarkers for colorectal cancer detection.

Colorectal cancer (CRC) is one of the most prevalent cancers and the second leading cause of cancer-related deaths in the United States. It is also one of the few cancers with established screening guidelines, however these methods have significant patient burden (e.g., time, invasive). In recent years, the development of liquid biopsy-based screening methods for biomarker detection have emerged as alternatives to traditional screening. Methylation biomarkers are of particular interest, and these markers can be identified and measured on circulating tumor and cell-free DNA. This perspective summarizes the current state of CRC screening and the potential integration of DNA methylation markers into liquid biopsy-based techniques. Finally, I discuss limitations to these methods and strategies for improvement. The continued development and implementation of liquid biopsy-based cancer screening approaches may provide an acceptable alternative to individuals unwilling to be screened by traditional methods.

Association of metformin use and cancer incidence: a systematic review and meta-analysis.

BACKGROUND: Metformin is among the most widely used antidiabetics medications because of its minimal toxicity, favorable safety profile, availability, and low cost. In addition to its role in diabetes management, metformin may reduce cancer risk. METHODS: We conducted a comprehensive systematic review and meta-analysis to investigate the association between metformin use and cancer risk, with evaluation by specific cancer type when possible. Applicable studies were identified in PubMed/MEDLINE, Embase, Cochrane Library, Web of Science, and Scopus from inception through March 7, 2023, with metformin use categorized as "ever" or "yes" and a cancer diagnosis as the outcome. Article quality was evaluated using National Heart, Lung, and Blood Institute guidelines, and publication bias was evaluated using the Egger test, Begg test, and funnel plots. Pooled relative risk (RR) estimates were calculated using random-effects models, and sensitivity analysis was completed through leave-one-out cross-validation. RESULTS: We included 166 studies with cancer incidence information in the meta-analysis. Reduced risk for overall cancer was observed in case-control studies (RR = 0.55, 95% confidence interval [CI] = 0.30 to 0.80) and prospective cohort studies (RR = 0.65, 95% CI = 0.37 to 0.93). Metformin use was associated with reduced gastrointestinal (RR = 0.79, 95% CI = 0.73 to 0.85), urologic (RR = 0.88, 95% CI = 0.78 to 0.99), and hematologic (RR = 0.87, 95% CI = 0.75 to 0.99) cancer risk. Statistically significant publication bias was observed within the studies (Egger P < .001). CONCLUSIONS: Metformin may be associated with a decreased risk of many cancer types, but high heterogeneity and risk of publication bias limit confidence in these results. Additional studies in populations without diabetes are needed to better understand the utility of metformin in cancer prevention.

Analysis of Body Mass Index in Early and Middle Adulthood and Estimated Risk of Gastrointestinal Cancer.

Importance: In a population with significantly increasing rates of individuals with overweight or obesity, understanding the association of obesity with long-term disease risk, such as cancer, is necessary to improve public health. Objective: To investigate the association between body mass index (BMI) and gastrointestinal (GI) cancer risk (colorectal cancer [CRC] and noncolorectal GI cancer) in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Design, Setting, and Participants: This retrospective cohort study was a secondary analysis of data from the PLCO Cancer Screening Trial. Participants aged 55 to 74 years were enrolled and randomized to the intervention (screening group) or control group at 10 screening centers between November 8, 1993, and July 2, 2001. The initial analysis of PLCO Cancer Screening Trial data occurred after 13 years of follow-up or December 31, 2009, whichever came first. Participants were reconsented in 2011 and either continued follow-up or refused additional follow-up. For those who reconsented, follow-up for incident cancers continued until December 31, 2014, or death, whichever occurred first. Data analysis for this secondary analysis was performed from April 2022 through November 2022. Exposures: Body mass index and aspirin use, defined as the frequency of use of aspirin or aspirin-containing substances in the last 12 months. Main Outcomes and Measures: The primary outcomes were the diagnoses of CRC and noncolorectal GI cancer. The association between BMI and cancer (CRC and noncolorectal GI cancer) was assessed using Cox proportional hazards regression modeling. The association between cancer risk and change in BMI was further analyzed at different ages, and an exploratory analysis was performed to evaluate GI cancer risk among aspirin users. Results: This analysis included 135 161 participants (median [range] age, 62 [55-78] years; 67 643 [50.0%] female). Overweight BMI in early adulthood (hazard ratio [HR], 1.23; 95% CI, 1.10-1.37) and overweight BMI in middle adulthood (HR, 1.23; 95% CI, 1.13-1.34) and later adulthood (HR, 1.21; 95% CI, 1.10-1.32) as well as obese BMI in middle adulthood (HR, 1.55; 95% CI, 1.38-1.75) and later adulthood (HR, 1.39; 95% CI, 1.25-1.54) were associated with increased risk of CRC. Similar results were observed for the association with overall GI and non-CRC GI risk and BMI in middle and later adulthood. Maintaining overweight or obese BMI or increasing BMI to overweight or obese in later adulthood was also associated with increased CRC risk. Aspirin use 3 or more times per week did not significantly modify this association. Conclusions and Relevance: In this secondary analysis of the PLCO Cancer Screening Trial, overweight and obese BMI in early and middle adulthood was associated with an elevated risk of CRC and noncolorectal GI cancers. The results of the current study prompt further exploration into the mechanistic role of obese BMI in carcinogenesis.

Association of metformin, aspirin, and cancer incidence with mortality risk in adults with diabetes.

BACKGROUND: Metformin and aspirin are commonly co-prescribed to people with diabetes. Metformin may prevent cancer, but in older people (over 70 years), aspirin has been found to increase cancer mortality. This study examined whether metformin reduces cancer mortality and incidence in older people with diabetes; it used randomization to 100 mg aspirin or placebo in the ASPirin in Reducing Events in the Elderly (ASPREE) trial to quantify aspirin's impact on metformin users. METHODS: Analysis included community-dwelling ASPREE participants (aged ≥70 years, or ≥65 years for members of US minority populations) with diabetes. Diabetes was defined as a fasting blood glucose level greater than 125 mg/dL, self-report of diabetes, or antidiabetic medication use. Cox proportional hazards regression models were used to analyze the association of metformin and a metformin-aspirin interaction with cancer incidence and mortality, with adjustment for confounders. RESULTS: Of 2045 participants with diabetes at enrollment, 965 were concurrently using metformin. Metformin was associated with a reduced cancer incidence risk (adjusted hazard ratio [HR] = 0.68, 95% confidence interval [CI] = 0.51 to 0.90), but no conclusive benefit for cancer mortality (adjusted HR = 0.72, 95% CI = 0.43 to 1.19). Metformin users randomized to aspirin had greater risk of cancer mortality compared with placebo (HR = 2.53, 95% CI = 1.18 to 5.43), but no effect was seen for cancer incidence (HR = 1.11, 95% CI = 0.75 to 1.64). The possible effect modification of aspirin on cancer mortality, however, was not statistically significant (interaction P = .11). CONCLUSIONS: In community-dwelling older adults with diabetes, metformin use was associated with reduced cancer incidence. Increased cancer mortality risk in metformin users randomized to aspirin warrants further investigation. ASPREE TRIAL REGISTRATION: ClinicalTrials.gov ID NCT01038583.

Supplemental B-Vitamins and Risk of Upper Gastrointestinal Cancers in the Women's Health Initiative.

B-vitamins contribute to DNA synthesis, maintenance, and regulation. Few studies have examined associations of supplemental sources of B-vitamins with the incidence of upper gastrointestinal (GI) cancers [including gastric (GCA) and esophageal (ECA) cancers]; the only prior study to comprehensively examine such intakes reported potential elevated risks of ECA. We examined 159,401 postmenopausal women, ages 50-79 years at baseline, including 302 incident GCA and 183 incident ECA cases, over 19 years of follow-up within the Women's Health Initiative observational study and clinic trials. Adjusted Cox regression models estimated hazard ratios (HR) and 95% confidence intervals (CI) for associations of supplemental B-vitamins [riboflavin (B2), pyridoxine (B6), folic acid (B9), or cobalamin (B12)] with GCA and ECA risk, respectively. Although HRs were generally below 1.0, we observed no statistically significant associations between supplemental intakes of any of the evaluated B-vitamins with the risk of GCA or ECA. As the first prospective study to comprehensively assess these associations, our findings do not corroborate prior research indicating potential harm from supplemental B-vitamin intake for upper GI cancer risk. This study adds evidence that supplemental intakes of B-vitamins may be used by postmenopausal women without regard to their relationship with upper GI cancer risk.

Methylated Septin9 (mSEPT9): A promising blood-based biomarker for the detection and screening of early-onset colorectal cancer.

Early-onset colorectal cancer (EOCRC), defined as a diagnosis under age 50, is an emerging public health burden. As many of these individuals fall outside of screening guidelines, the development of a minimally invasive, accurate screening modality for this population is warranted. We evaluated the FDA-approved blood-based biomarker methylated Septin9 (mSEPT9) test as screening tool for EOCRC. EOCRC plasma, healthy plasma, and serum-free conditioned media from cancer cell lines was collected. Cell-free DNA (cfDNA) was isolated and bisulfite converted for use in the assay. mSEPT9 and ACTB measured using Epi proColon® V2.0. EOCRC plasma was collected at Massachusetts General Hospital (2005-2019) and controls were collected at the National Institutes of Health and by ZenBio Inc. (prior to 2019). Twenty-seven EOCRC cases, 48 healthy controls <50 years old, and 39 healthy controls ≥50 years old were included in this study. mSEPT9 was detected more frequently in EOCRC cases (88.9%) compared to healthy controls age <50 (4.2%) and ≥50 (15.4%), respectively (p<0.001). The sensitivity, specificity, positive predictive value, and negative predictive values of the mSEPT9 assay to detect EOCRC was 90.8% (95% CI: 84.7-96.9%), 88.9% (95% CI: 77.0-100.0%), 96.3% (95% CI: 92.3-100.0%), and 75.0% (95% CI 60.0-90.0%), respectively, compared to all healthy controls. mSEPT9 cfDNA level was an independent predictor of survival (p=0.02). mSEPT9 is a sensitive and specific biomarker for EOCRC detection. These results suggest that mSEPT9 may be useful in the detection of EOCRC, providing a minimally invasive method for screening in this growing population of CRC patients.

Comparing Barriers and Facilitators to Adolescent and Young Adult Clinical Trial Enrollment Across High- and Low-Enrolling Community-Based Clinics.

BACKGROUND: Adolescent and young adult (AYA) patients with cancer are underrepresented on cancer clinical trials (CCTs), and most AYAs are treated in the community setting. Past research has focused on individual academic institutions, but factors impacting enrollment vary across institutions. Therefore, we examined the patterns of barriers and facilitators between high- and low-AYA enrolling community-based clinics to identify targets for intervention. MATERIALS AND METHODS: We conducted 34 semi-structured interviews with stakeholders employed used at National Cancer Institute Community Oncology Research Program (NCORP) affiliate sites ("clinics"). Stakeholders (eg, clinical research associates, patient advocates) were recruited from high- and low-AYA enrolling clinics. We conducted a content analysis and calculated the percentage of stakeholders from each clinic type that reported the barrier or facilitator. A 10% gap between high- and low-enrollers was considered the threshold for differences. RESULTS: Both high- and low-enrollers highlighted insufficient resources as a barrier and the presence of a patient eligibility screening process as a facilitator to AYA enrollment. High-enrolling clinics reported physician gatekeeping as a barrier and the improvement of departmental collaboration as a facilitator. Low-enrollers reported AYAs' uncertainty regarding the CCT process as a barrier and the need for increased physician endorsement of CCTs as a facilitator. CONCLUSIONS: High-enrolling clinics reported more barriers downstream in the enrollment process, such as physician gatekeeping. In contrast, low-enrolling clinics struggled with the earlier steps in the CCT enrollment process, such as identifying eligible trials. These findings highlight the need for multi-level, tailored interventions rather than a "one-size-fits-all" approach to improve AYA enrollment in the community setting.

Role of Aspirin in Gastric Cancer Prevention.

The role of aspirin in cancer prevention has been well described for multiple cancers, with strong data for gastrointestinal cancers. Studies, primarily conducted in colorectal cancer, suggest that aspirin exerts its cancer-preventive effects through the inhibition of gastrointestinal inflammation. Compared with colorectal cancer, the role of aspirin in gastric cancer prevention is less well described, however it stands to reason that aspirin and/or other nonsteroidal anti-inflammatory drugs may inhibit gastric cancer progression through the inhibition of COX-2. As discussed in this issue of Cancer Prevention Research, aspirin may prevent gastric cancer, albeit it appears to exert a disparate effect in men and women, the reason for which remain unclear. These results expand upon prior studies by prospectively examining aspirin use at a wider range of doses and durations in non-Asian participants and lend support to observations from previously conducted studies in Asian populations. See related article, p. 265.

Multi-Cancer Early Detection Tests: Current Progress and Future Perspectives.

Advances in cancer screening and early detection methodologies may lead to the detection of precancerous lesions or early-stage cancer. The development of blood-based multi-cancer early detection (MCED) tests may aid in this challenge. Furthermore, MCED tests have the potential to address early detection gaps for cancers with and without screening modalities and lessen cancer disparities, but many unknowns remain. In this issue, Clarke and colleagues describe stage- and cancer-specific incidence and survival, derived from Surveillance, Epidemiology and End Results Program Data, stratified by race/ethnicity and sex. The investigators discuss the potential to identify earlier-stage cancers (stage shift) that could improve overall patient outcomes. In a simulation model, the authors found fewer cancer-related deaths when cancers were down-staged at the time of diagnosis. In this commentary, we discuss some unanswered questions in using MCED tests for screening, as well as what stage shifting may actually mean for patient outcomes. See related article by Clarke et al., p. 521.

Barriers and Facilitators to Adolescent and Young Adult Cancer Trial Enrollment: NCORP Site Perspectives.

Background: Although it is well documented that adolescents and young adults (AYAs) with cancer have low participation in cancer clinical trials (CCTs), the underlying reasons are not well understood. We used the National Cancer Institute Community Oncology Research Program (NCORP) network to identify barriers and facilitators to AYA CCT enrollment, and strategies to improve enrollment at community-based and minority and/or underserved sites. Methods: We performed one-on-one semistructured qualitative interviews with stakeholders (NCORP site principle investigators, NCORP administrators, physicians involved in enrollment, lead clinical research associates or clinical research nurses, nurse navigators, regulatory research associates, patient advocates) in the AYA CCT enrollment process. NCORP sites that included high and low AYA-enrolling affiliate sites and were diverse in geography and department representation (eg, pediatrics, medical oncology) were invited to participate. All interviews were recorded and transcribed. Themes related to barriers and facilitators and strategies to improve enrollment were identified. Results: We conducted 43 interviews across 10 NCORP sites. Eleven barriers and 13 facilitators to AYA enrollment were identified. Main barriers included perceived limited trial availability and eligibility, physician gatekeeping, lack of provider and research staff time, and financial constraints. Main facilitators and strategies to improve AYA enrollment included having a patient screening process, physician endorsement of trials, an "AYA champion" on site, and strong communication between medical and pediatric oncology. Conclusions: Stakeholders identified several opportunities to address barriers contributing to low AYA CCT enrollment at community-based and minority and/or underserved sites. Results of this study will inform development and implementation of targeted interventions to increase AYA CCT enrollment.

Evaluation of Aspirin Use With Cancer Incidence and Survival Among Older Adults in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

Importance: Many studies have evaluated the long-term benefits of aspirin use; however, the association of aspirin use with cancer incidence and survival in older individuals remains uncertain. Additional population-based evidence of this association is necessary to better understand any possible protective effects of aspirin in older adults. Objective: To investigate the association of aspirin use with risk of developing new cancers and site-specific cancer-associated survival in bladder, breast, esophageal, gastric, pancreatic, and uterine cancers. Design, Setting, and Participants: This cohort study used data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Participants were aged 65 years or older at baseline (1993-2001) or reached age 65 during follow-up. Data analysis was conducted from January to June 2020. Main Outcomes and Measures: Incidence of and survival from the investigated cancer types. Univariable and multivariable hazard ratios (HRs) and 95% CIs were calculated using Cox proportional hazards regression modeling, adjusting for covariates. Multivariable models for incidence included time-varying covariates. Results: A total of 139 896 individuals (mean [SD] age at baseline, 66.4 [2.4] years; 71 884 [51.4%] women; 123 824 [88.5%] non-Hispanic White individuals) were included in the analysis. During the study period, 32 580 incident cancers (1751 [5.4%] bladder, 4552 [14.0%] breast, 332 [1.0%] esophageal, 397 [1.2%] gastric, 878 [2.7%] pancreatic, and 716 [2.2%] uterine cancers) were reported. Aspirin use was not associated with incidence of any of the investigated cancer types among individuals aged 65 years or older. Multivariable regression analysis demonstrated that aspirin use at least 3 times/week was associated with increased survival among patients with bladder (HR, 0.67; 95% CI, 0.51-0.88) and breast (HR, 0.75; 95% CI, 0.59-0.96) cancers but not among those with esophageal, gastric, pancreatic, or uterine cancer. A similar association of any aspirin use with bladder (HR, 0.75; 95% CI, 0.58-0.98) and breast (HR, 0.79; 95% CI, 0.63-0.99) cancer survival was observed. Conclusions and Relevance: In the current study, any aspirin use and aspirin use at least 3 times/week was associated with improved bladder and breast cancer survival. Associations between aspirin use and incidence of any of the investigated cancers or between aspirin use and esophageal, gastric, pancreatic, or uterine cancer survival were not observed.

Association of Common Use Pharmaceuticals in Reducing Risk of Esophageal Adenocarcinoma: A SEER-Medicare Analysis.

Barrett's esophagus (BE), a recognized risk factor for esophageal adenocarcinoma (EAC), is routinely managed with proton pump inhibitors (PPIs) when symptomatic. Several lines of evidence suggest that PPIs may prevent malignant transformation. Chronic use of other common drugs, namely, statins nonsteroidal anti-inflammatory drugs (NSAIDs) and metformin, may also interfere with BE carcinogenesis, but confirmatory evidence is lacking. We identified 1,943 EAC cases and 19,430 controls (matched 10:1) between 2007 and 2013 that met our specified inclusion criteria in the SEER-Medicare database. Conditional logistic regression was used to generate odds ratios (OR) and 95% confidence intervals (95% CI). Wald χ2 tests were used to assess significance of covariates. Compared with controls, EAC cases had a higher prevalence of BE (26.2%). Use of PPIs, NSAIDs, statins, or metformin reduced the odds of EAC (PPIs: 0.10; 95% CI, 0.09-0.12; NSAIDs: 0.62; 95% CI, 0.51-0.74; statins: 0.15; 95% CI, 0.13-0.17; metformin: 0.76; 95% CI, 0.62-0.93). When stratified by BE, these associations persisted, though no association was found between NSAID use and EAC risk for participants with BE. Dual use of PPIs with NSAIDs or statins, and NSAID, statin, or metformin use alone also showed significant EAC risk reduction among all participants and those without BE. Use of PPIs alone and with NSAIDs, statins, or metformin was associated with reduced risk of EAC; however, a history of BE may diminish drug efficacy. These results indicate that common pharmacologic agents alone or in combination may decrease EAC development.Prevention Relevance: The use of common drugs, such as proton pump inhibitors, statins, non-steroidal anti-inflammatory drugs, or metformin, may reduce one's risk of developing esophageal adenocarcinoma. These results suggest that repurposing agents often used for common chronic conditions may be a new strategy for cancer prevention efforts.

Immuno-Interception for Patients with High-Risk Cancer.

Cancer immune-interception for prevention of recurrence in patients with high-risk familial cancer like Muir-Torre syndrome or Lynch syndrome using immune checkpoint blockade inhibitors is a promising approach. Albeit, as described in a case report by Pollak and colleagues in the April 2020 issue of Cancer Prevention Research, it has the potential to be used as immune-interceptive with alternative dosing regimens for cancers with microsatellite instability. The combination of additional cancer preventive and immunopreventive approaches, such as vaccines and minimal dose of immune checkpoint blockade inhibitors, is another unexplored modality for cancer interception in high-risk individuals.

Systematic review of barriers and facilitators to clinical trial enrollment among adolescents and young adults with cancer: Identifying opportunities for intervention.

Adolescents and young adults (AYAs) are underrepresented in cancer clinical trials (CCTs). Limited trial enrollment slows progress in improving survival rates and prevents the collection of valuable biospecimens. A systematic literature review was conducted to assess barriers and facilitators to AYA enrollment in CCTs and to identify opportunities to improve enrollment. The PubMed MEDLINE, Web of Science, Scopus, and PsycINFO databases were searched to identify studies relevant to AYA CCT enrollment. Eligibility criteria included the qualitative and/or quantitative evaluation of barriers and facilitators to AYA enrollment. One hundred fifty-five unique publications were identified; 13 were included in the final analysis. Barriers to AYA enrollment in CCTs included a lack of existing trials applicable to the patient population, limited access to available CCTs, and a lack of physician awareness of relevant trials. Facilitators of enrollment included optimizing the research infrastructure, improving the awareness of available CCTs among providers, and enhancing communication about CCTs between providers and patients. In conclusion, the limited available research reports institution- and patient-level barriers and facilitators to AYA CCT enrollment. Because of persistent disparities in AYA enrollment, there is an urgent need to further identify the barriers and facilitators to AYA CCT enrollment to determine actionable areas for intervention.

Thyroid Incidentalomas in Association With Low-Dose Computed Tomography in the National Lung Screening Trial.

Advances in cancer screening methods have opened avenues for incidental findings and cancer overdiagnosis. We performed a secondary analysis of the National Lung Screening Trial (enrollment from 2002-2004), a randomized controlled trial comparing low-dose computed tomography (LDCT; n = 26,722) with chest radiography (CXR; n = 26,732) for lung cancer detection, to examine incidental findings related to thyroid cancer (ThCa). Three screening rounds were included, and median follow-up was 6.6 years for LDCT and 6.5 years for CXR. Radiologists reported lung and non-lung-related abnormalities. In the LDCT arm, 5.7%, 4.7%, and 4.5% of participants had abnormalities above the diaphragm (AADs) detected at baseline, year 1, and year 2, respectively, compared with 2.3%, 1.5%, and 1.3% in the CXR arm. In the LDCT arm, 205 AADs (7.0%) were thyroid-related. Overall, 60 ThCas were reported, 35 in the LDCT arm and 25 in the CXR arm (P = 0.2). In the LDCT arm, participants with a prior AAD had a 7.8-fold increased risk (95% confidence interval: 4.0, 15.1) of ThCa compared with those who did not have an AAD. Early and persistent excess of ThCas diagnosed earlier in the LDCT arm suggests overdiagnosis. The use of sensitive screening modalities for early detection of lung cancer might result in the discovery of thyroid incidentalomas.

Increasing Incidence of Colorectal Cancer in Young Adults.

BACKGROUND: Colorectal cancer (CRC) incidence and mortality has been declining in the U.S. Despite success in reducing CRC incidence, incidence of early-onset CRC has increased markedly. In this study, we identified age-related disparities in CRC incidence and mortality, and investigated differences in anatomical distribution of colon cancers between populations. METHODS: CRC trends were evaluated using Surveillance, Epidemiology, and End Results Program Data from 1980-2016 for individuals under age 50 and 50 years and older. Rates and ratios were calculated using SEER∗Stat. Regression analyses were calculated using Joinpoint. RESULTS: Increased CRC incidence among individuals under age 50 was observed. Among individuals under age 50, incidence-based mortality (IBM) stabilized, while incidence and IBM decreased for individuals aged 50 years and older. Normalized trends indicated increased rectal cancer incidence for individuals under age 50, particularly among individuals aged 30-39. Similar incidence of proximal and distal colon cancers in individuals under age 50 was observed, while colon cancers in individuals aged 50 and older were primarily distal. CONCLUSIONS: We found age-related disparities in CRC incidence and IBM between individuals under age 50 and age 50 years and older. Increasing incidence rates of rectal cancer substantially accounts for this disparity among individuals under age 50. The escalating trends of early-onset CRC warrant investigation into the factors leading to the population-level trends.