Trends in the Incidence of Early-Onset Colorectal Adenocarcinoma Among Black and White US Residents Aged 40 to 49 Years, 2000-2017

IMPORTANCE

Early-onset colorectal cancer incidence rates are rising faster in White individuals than Black individuals. However, prior National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) racial stratification analyses used smaller SEER 13 databases, combined patients under age 50 years, did not stratify by sex, and did not focus on adenocarcinoma histologic subtypes (screening target).

OBJECTIVE

To perform a race- and sex-stratified adenocarcinoma incidence rate analysis in individuals aged 40 to 49 years using larger SEER 18 databases with expanded race data to better understand the colorectal cancer burden in those at or approaching screening age.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used 2000 to 2017 SEER 18 annual age-adjusted colorectal cancer incidence rates stratified by anatomic subsite (colon or rectum), adenocarcinoma histology, race (non-Hispanic Black or non-Hispanic White), and sex for individuals aged 40 to 49 years, and yearly annual percent change (APC) incidence rates were calculated. Annual rate ratios (ARRs) between subgroups were determined. Statistical analysis was performed from January to March 2021.

MAIN OUTCOMES AND MEASUREMENTS

Early-onset colorectal cancer incidence rates, APCs, and ARRs.

RESULTS

In this study, a total of 46 728 colorectal cancer cases were identified in 45 429 patients aged 40 to 49 years from 2000 to 2017. Among the 45 429 patients included in this study, 6480 (14.2%) were Black and 27 426 (60.4%) were White; the mean (SD) age was 45.5 (2.8) years. Among White individuals aged 40 to 49 years, colorectal adenocarcinoma incidence rates increased from 19.6 per 100 000 person-years in 2000 to 25.2 per 100 000 person-years in 2017 (APC, 1.6; 95% CI, 1.3 to 1.9). Among Black individuals aged 40 to 49 years, colorectal adenocarcinoma incidence rates were not significantly changed (26.4 per 100 000 person-years in 2000 and 25.8 per 100 000 person-years in 2017 [APC, -0.03; 95% CI, -0.5 to 0.5]). There were no significant differences in ARRs of absolute colorectal incidence rates between White and Black individuals from 2014 to 2017. Rectal-only absolute adenocarcinoma incidence rates in Black and White individuals remained similar from 2000 to 2008 but significantly diverged in 2009. As of 2017, rectal absolute incidence rates were 39% higher among White individuals than among Black individuals with increasing APC (APC, 2.2; 95% CI, 1.6 to 2.8) whereas rectal adenocarcinoma incidence rates among Black individuals were decreasing, although the APC was not statistically significant (APC, -1.4; 95% CI, -2.6 to 0.1). Absolute colonic adenocarcinoma incidence rates remained higher in Black individuals. The study subgroups with the largest divergence in APCs were rectal adenocarcinoma in White vs Black women (APC of 2.2 [95% CI, 1.6 to 2.8] vs APC of -1.7 [95% CI, -3.6 to 0.3], respectively).

CONCLUSIONS AND RELEVANCE

This study found that colorectal adenocarcinoma incidence rates in people aged 40 to 49 years were increasing among White individuals but stabilized among Black individuals with absolute incidence rates becoming equivalent. Absolute rectal adenocarcinoma incidence rates were 39% lower in Black individuals with a widening disparity in rectal cancer between White and Black women. Possible contributors include introduction of a screening threshold of age 45 years in Black individuals in 2008. Although the average-risk screening age has now shifted to age 45 years in all racial groups, these data can help motivate real-world implementation of guidelines to maximize screening rates that have historically been suboptimal in younger individuals.

Inflammation as a Regulator of the Renin-Angiotensin System and Blood Pressure

PURPOSE OF REVIEW

Mechanisms facilitating progression of hypertension via cross stimulation of the renin-angiotensin system (RAS) and inflammation have been proposed. Accordingly, we review and update evidence for regulation of RAS components by pro-inflammatory factors.

RECENT FINDINGS

Angiotensin II (Ang II), which is produced by RAS, induces vasoconstriction and consequent blood pressure elevation. In addition to this direct action, chronically elevated Ang II stimulates several pathophysiological mechanisms including generation of oxidative stress, stimulation of the nervous system, alterations in renal hemodynamics, and activation of the immune system. In particular, an activated immune system has been shown to contribute to the development of hypertension. Recent studies have demonstrated that immune cell-derived pro-inflammatory cytokines regulate RAS components, further accelerating systemic and local Ang II formation. Specifically, regulation of angiotensinogen (AGT) production by pro-inflammatory cytokines in the liver and kidney is proposed as a key mechanism underlying the progression of Ang II-dependent hypertension.

Intestinal inflammation requires FOXO3 and prostaglandin E2-dependent lipogenesis and elevated lipid droplets

Intestinal inflammation has been recently characterized by the dysregulation of lipids as metabolic and energy sources, revealing a novel feature of its pathophysiology. Because intracellular lipids, stored in dynamic lipid droplets (LDs), provide energy for cellular needs, we investigated whether they play a role in intestinal inflammation. In the inflamed intestine of mice, elevated LDs were found in colonic and infiltrating immune cells as shown by staining for the LD coat protein PLIN2 and for lipids with BODIPY. In colonic cells, TNF stimulated LD increases by receptor signaling rely on phosphatidylinositol 3-kinase activation. Downstream, TNF triggered a negative regulatory loop between LDs and the transcription factor FOXO3. This was shown in the colon of Foxo3-deficient mice, where elevation in PLIN2 and lipids were further facilitated by inflammation and were more prominent relative to wild-type, whereas, in colonic cells, inhibition of lipogenesis blocked the TNF-mediated loss of FOXO3. Furthermore, blockade of PGE2 synthesis abrogated TNF-stimulated increases in LDs and FOXO3 inactivation. We found in colonic tissue of Foxo3-deficient mice higher levels of cyclooxygenase-2, a mediator of prostaglandin E2 (PGE2) synthesis, supporting involvement of PGE2 in the LD-FOXO3 regulatory loop. Ultimately, TNF-stimulated lipogenesis leading to elevated LDs facilitated NF-κB-mediated increases in IL-8 protein, which is associated with the surface of LDs found in the lumina of the endoplasmic reticulum and Golgi apparatus. This novel immunometabolic mechanism of colonic inflammation involving elevated LDs could provide opportunities for new treatment options.

Macrophage-derived IL-6 contributes to ANG II-mediated angiotensinogen stimulation in renal proximal tubular cells

The development of ANG II-dependent hypertension involves increased infiltration of macrophages (MΦ) and T cells into the kidney and the consequent elevation of intrarenal cytokines including IL-6, which facilitates the progression of hypertension and associated kidney injury. Intrarenal renin-angiotensin system (RAS) activation, including proximal tubular angiotensinogen (AGT) stimulation, has also been regarded as a cardinal mechanism contributing to these diseases. However, the interaction between immune cells and intrarenal RAS activation has not been fully delineated. Therefore, the present study investigated whether ANG II-treated MΦ induce AGT upregulation in renal proximal tubular cells (PTCs). MΦ were treated with 0-10(-6) M ANG II for up to 48 h. PTCs were incubated with the collected medium from MΦ. In ANG II-treated MΦ, IL-6 mRNA and protein levels were increased (1.86 ± 0.14, protein level, ratio to control); moreover, IL-6 levels were higher than TNF-α and IL-1β in culture medium isolated from ANG II-treated MΦ. Elevated AGT expression (1.69 ± 0.04, ratio to control) accompanied by phosphorylated STAT3 were observed in PTCs that received culture medium from ANG II-treated MΦ. The addition of a neutralizing IL-6 antibody to the collected medium attenuated phosphorylation of STAT3 and AGT augmentation in PTCs. Furthermore, a JAK2 inhibitor also suppressed STAT3 phosphorylation and AGT augmentation in PTCs. These results demonstrate that ANG II-induced IL-6 elevation in MΦ enhances activation of the JAK-STAT pathway and consequent AGT upregulation in PTCs, suggesting involvement of an immune response in driving intrarenal RAS activity.

Epidermal growth factor receptor mediated proliferation depends on increased lipid droplet density regulated via a negative regulatory loop with FOXO3/Sirtuin6

The proliferation of colon cancer cells is mediated in part by epidermal growth factor receptor (EGFR) signaling and requires sustained levels of cellular energy to meet its high metabolic needs. Intracellular lipid droplets (LDs) are a source of energy used for various cellular functions and they are elevated in density in human cancer, yet their regulation and function are not well understood. Here, in human colon cancer cells, EGF stimulates increases in LD density, which depends on EGFR expression and activation as well as the individual cellular capacity for lipid synthesis. Increases in LDs are blockaded by inhibition of PI3K/mTOR and PGE2 synthesis, supporting their dependency on select upstream pathways. In colon cancer cells, silencing of the FOXO3 transcription factor leads to down regulation of SIRT6, a negative regulator of lipid synthesis, and consequent increases in the LD coat protein PLIN2, revealing that increases in LDs depend on loss of FOXO3/SIRT6. Moreover, EGF stimulates loss of FOXO3/SIRT6, which is blockaded by the inhibition of upstream pathways as well as lipid synthesis, revealing existence of a negative regulatory loop between LDs and FOXO3/SIRT6. Elevated LDs are utilized by EGF treatment and their depletion through the inhibition of lipid synthesis or silencing of PLIN2 significantly attenuates proliferation. This novel mechanism of proliferative EGFR signaling leading to elevated LD density in colon cancer cells could potentially be therapeutically targeted for the treatment of tumor progression.

A comparison of linaclotide and lubiprostone dosing regimens on ion transport responses in human colonic mucosa

Linaclotide, a synthetic guanylyl cyclase C (GC-C) agonist, and the prostone analog, Lubiprostone, are approved to manage chronic idiopathic constipation and constipation-predominant irritable bowel syndrome. Lubiprostone also protects intestinal mucosal barrier function in ischemia. GC-C signaling regulates local fluid balance and other components of intestinal mucosal homeostasis including epithelial barrier function. The aim of this study was to compare if select dosing regimens differentially affect linaclotide and lubiprostone modulation of ion transport and barrier properties of normal human colonic mucosa. Normal sigmoid colon biopsies from healthy subjects were mounted in Ussing chambers. Tissues were treated with linaclotide, lubiprostone, or vehicle to determine effects on short-circuit current (I_sc). Subsequent I_sc responses to the cAMP agonist, forskolin, and the calcium agonist, carbachol, were also measured to assess if either drug caused desensitization. Barrier properties were assessed by measuring transepithelial electrical resistance. I_sc responses to linaclotide and lubiprostone were significantly higher than vehicle control when administered bilaterally or to the mucosal side only. Single versus cumulative concentrations of linaclotide showed differences in efficacy while cumulative but not single dosing caused desensitization to forskolin. Lubiprostone reduced forskolin responses under all conditions. Linaclotide and lubiprostone exerted a positive effect on TER that was dependent on the dosing regimen. Linaclotide and lubiprostone increase ion transport responses across normal human colon but linaclotide displays increased sensitivity to the dosing regimen used. These findings may have implications for dosing protocols of these agents in patients with constipation.