Dennis J. Ahnen

Colorectal cancer statistics, 2017: Colorectal Cancer Statistics, 2017

Colorectal cancer (CRC) is one of the most common malignancies in the United States. Every 3 years, the American Cancer Society provides an update of CRC incidence, survival, and mortality rates and trends. Incidence data through 2013 were provided by the Surveillance, Epidemiology, and End Results program, the National Program of Cancer Registries, and the North American Association of Central Cancer Registries. Mortality data through 2014 were provided by the National Center for Health Statistics. CRC incidence rates are highest in Alaska Natives and blacks and lowest in Asian/Pacific Islanders, and they are 30% to 40% higher in men than in women. Recent temporal patterns are generally similar by race and sex, but differ by age. Between 2000 and 2013, incidence rates in adults aged ≥50 years declined by 32%, with the drop largest for distal tumors in people aged ≥65 years (incidence rate ratio [IRR], 0.50; 95% confidence interval [95% CI], 0.48‐0.52) and smallest for rectal tumors in ages 50 to 64 years (male IRR, 0.91; 95% CI, 0.85‐0.96; female IRR, 1.00; 95% CI, 0.93‐1.08). Overall CRC incidence in individuals ages ≥50 years declined from 2009 to 2013 in every state except Arkansas, with the decrease exceeding 5% annually in 7 states; however, rectal tumor incidence in those ages 50 to 64 years was stable in most states. Among adults aged <50 years, CRC incidence rates increased by 22% from 2000 to 2013, driven solely by tumors in the distal colon (IRR, 1.24; 95% CI, 1.13‐1.35) and rectum (IRR, 1.22; 95% CI, 1.13‐1.31). Similar to incidence patterns, CRC death rates decreased by 34% among individuals aged ≥50 years during 2000 through 2014, but increased by 13% in those aged <50 years. Progress against CRC can be accelerated by increasing initiation of screening at age 50 years (average risk) or earlier (eg, family history of CRC/advanced adenomas) and eliminating disparities in high‐quality treatment. In addition, research is needed to elucidate causes for increasing CRC in young adults. CA Cancer J Clin 2017.

Characterization of ischemia-induced loss of epithelial polarity

SummaryTotal renal ischemia for various time intervals (0–50) min) resulted in the rapid and duration-dependent redistribution of polarized membrane lipids and proteins in renal proximal tubule cells. Following only 15 min of ischemia, apical membrane enrichment of NaK-ATPase, normally a basolateral membrane (BLM) enzyme, had increased (1.6±0.6vs. 2.9±1.2,P<0.01). In vivo histochemical localization of NaK-ATPase showed reaction product throughout the apical microvillar region. PTH-stimulatable adenylate cyclase, another BLM protein, was also found in ischemic but not control apical membrane fractions. One dimensional SDS-PAGE showed four bands, present in control BLM and ischemic apical membranes, which could not be found in control apical membrane fractions. Immunohistochemical localization of leucine aminopeptidase (LAP) showed the enzyme was limited to the apical domain in control cells. Following ischemic injury (50 min), LAP staining could be seen within the cell and along the BLM. Following 24 hr of reperfusion, the BLM distribution of LAP was further enhanced. With cellular recovery from ischemic injury (5 days), LAP was again only visualized in the apical membrane. Duration-dependent alterations in apical and BLM lipids were also observed. Apical sphingomyelin and phosphatidylserine and the cholesterol-tophospholipid ratio decreased rapidly while apical phosphatidylcholine and phosphatidylinositol increased. Taken together, these results indicate renal ischemia causes rapid duration-dependent reversible loss of surface membrane polarity in proximal tubule cells.

Polymorphisms in Base Excision Repair Genes as Colorectal Cancer Risk Factors and Modifiers of the Effect of Diets High in Red Meat

Background: A diet high in red meat is an established colorectal cancer (CRC) risk factor. Carcinogens generated during meat cooking have been implicated as causal agents and can induce oxidative DNA damage, which elicits repair by the base excision repair (BER) pathway. Methods: Using a family-based study, we investigated the role of polymorphisms in 4 BER genes (APEX1 Gln51His, Asp148Glu; OGG1 Ser236Cys; PARP Val742Ala; and XRCC1 Arg194Trp, Arg280His, Arg399Gln) as potential CRC risk factors and modifiers of the association between diets high in red meat or poultry and CRC risk. We tested for gene–environment interactions using case-only analyses (n = 577) and compared statistically significant results with those obtained using case-unaffected sibling comparisons (n = 307 sibships). Results: Carriers of the APEX1 codon 51 Gln/His genotype had a reduced CRC risk compared with carriers of the Gln/Gln genotype (odds ratio (OR) = 0.15, 95% CI = 0.03–0.69, P = 0.015). The association between higher red meat intake (>3 servings per week) and CRC was modified by the PARP Val762Ala single-nucleotide polymorphisms (SNP; case-only interaction P = 0.026). This SNP also modified the association between higher intake of high-temperature cooked red meat (case-only interaction P = 0.0009). Conclusions: We report evidence that the BER pathway PARP gene modifies the association of diets high in red meat cooked at high temperatures with risk of CRC. Impact: Our findings suggest a contribution to colorectal carcinogenesis of free radical damage as one of the possible harmful effects of a diet high in red meat. Cancer Epidemiol Biomarkers Prev; 19(12); 3167–73. ©2010 AACR.

ASSESSMENT OF MUTATIONS IN KI-RAS AND P53 IN COLON CANCERS FROM AZOXYMETHANE- AND DIMETHYLHYDRAZINE-TREATED RATS

Mutations in the Ki‐ras oncogene and the p53 tumor suppressor gene are known to occur at high frequencies in human colon cancers. We measured the frequency of mutations in these two genes in colon adenocarcinomas obtained from a widely used experimental model of human colon carcinogenesis: F344 rats treated with the carcinogens azoxymethane (AOM) or dimethylhydrazine (DMH). We detected codon 12 mutations in Ki‐ras in approximately 60% of colon adenocarcinomas induced by either carcinogen. We characterized the rat p53 intron‐exon junctions to construct primers for polymerase chain reaction amplification of this gene. We discovered that the rat p53 gene was structurally different from the human p53 gene, as the rat gene was missing one intron between exons 6 and 7. Both single‐stranded DNA conformational polymorphism analysis and direct DNA sequencing of the highly conserved regions of rat exons 5–7 were conducted because the corresponding human regions (exons 5–8) have been reported as being mutated most frequently in human colon cancers. Using these methods, we were unable to identify any p53 mutations in the highly conserved regions of exons 5–7 in either AOM‐ or DMH‐induced colon adenocarcinomas. These data confirm that Ki‐ras was mutated in most colon cancers in AOM‐ or DMH‐treated rats but indicate that molecular alterations in the p53 gene, if they occur in this animal model, are different from most p53 mutations in human colon cancers. Mol. Carcinog. 19:137–144, 1997.

Genetic Variants in CYP2R1, CYP24A1, and VDR Modify the Efficacy of Vitamin D3 Supplementation for Increasing Serum 25-Hydroxyvitamin D Levels in a Randomized Controlled Trial

CONTEXT Adequate serum 25-hydroxyvitamin D concentrations, [25(OH)D], are required for optimal bone health, and low levels are associated with chronic diseases. OBJECTIVE We investigated whether 41 candidate single nucleotide polymorphisms (SNPs) in vitamin D and calcium pathway genes (GC, DHCR7, CYP2R1, CYP27B1, CYP24A1, VDR, and CASR) are associated with [25(OH)D] or modify the increase in [25(OH)D] from vitamin D3 supplementation. DESIGN AND SETTING Baseline and year 1 [25(OH)D] measurements from a randomized controlled trial conducted at 11 clinical centers in the United States. PARTICIPANTS A total of 1787 healthy non-Hispanic white participants aged 45-75 years. INTERVENTIONS Vitamin D3 (1000 IU/d), calcium carbonate (1200 mg/d elemental), both, or placebo. MAIN OUTCOME MEASURES Genotype main effects and interactions with vitamin D3 treatment estimated using multiple linear regression. RESULTS The baseline serum [25(OH)D] was 25.4 ± 8.7 ng/mL (mean ± SD). Associations with baseline levels were discovered for SNPs in CYP24A1 (rs2209314, rs2762939) and confirmed for SNPs in GC and CYP2R1. After 1 year, [25(OH)D] increased on average by 6.1 ± 8.9 ng/mL on vitamin D3 treatment and decreased by 1.1 ± 8.4 ng/mL on placebo. The increase in [25(OH)D] due to vitamin D3 supplementation was modified by genotypes at rs10766197 near CYP2R1, rs6013897 near CYP24A1, and rs7968585 near VDR. CONCLUSIONS The increase in [25(OH)D] attributable to vitamin D3 supplementation may vary according to common genetic differences in vitamin D 25-hydroxylase (CYP2R1), 24-hydroxylase (CYP24A1), and the vitamin D receptor (VDR) genes. These findings have implications for achieving optimal vitamin D status and potentially for vitamin D-related health outcomes.

Sialosyl-Tn antigen: initial report of a new marker of malignant progression in long-standing ulcerative colitis.

BACKGROUND & AIMS Expression of the mucin-associated carbohydrate antigen sialosyl-Tn (STn) correlates with malignant transformation in sporadic colonic neoplasms. The aim of this study was to analyze STn antigen expression in patients with long-standing ulcerative colitis (UC). METHODS STn antigen was assessed by immunohistochemistry in archival tissues. Study A was a retrospective chronological case-control study. Serial surveillance colonoscopic biopsy specimens without inflammation or dysplasia were analyzed in 7 patients who developed colon cancer and in 8 controls who did not develop colon cancer. Study B analyzed the anatomic distribution of STn expression in 17 cancer-bearing (case) and 6 cancer-free (control) colectomy specimens from patients with UC. In some colectomy specimens, STn was compared with aneuploidy, which was determined by flow cytometry. RESULTS In study A, among the 7 patients with UC who developed cancer, 6 patients (86%) expressed STn in at least one prior nondysplastic surveillance biopsy specimen from the same site. Only 3 of 8 control patients (38%) expressed STn. In study B, STn was expressed in 40 of 82 specimens (49%) from cancer-bearing colons but only 8 of 62 specimens (13%) from cancer-free colons. STn was expressed in most aneuploid areas but was also found in diploid, nondysplastic mucosa. CONCLUSIONS STn antigen seems to be a promising marker of cancer risk in patients with UC.

Understanding the contribution of family history to colorectal cancer risk and its clinical implications: A state‐of‐the‐science review

Persons with a family history (FH) of colorectal cancer (CRC) or adenomas that are not due to known hereditary syndromes have an increased risk for CRC. An understanding of these risks, screening recommendations, and screening behaviors can inform strategies for reducing the CRC burden in these families. A comprehensive review of the literature published within the past 10 years has been performed to assess what is known about cancer risk, screening guidelines, adherence and barriers to screening, and effective interventions in persons with an FH of CRC and to identify FH tools used to identify these individuals and inform care. Existing data show that having 1 affected first‐degree relative (FDR) increases the CRC risk 2‐fold, and the risk increases with multiple affected FDRs and a younger age at diagnosis. There is variability in screening recommendations across consensus guidelines. Screening adherence is <50% and is lower in persons under the age of 50 years. A providers recommendation, multiple affected relatives, and family encouragement facilitate screening; insufficient collection of FH, low knowledge of guidelines, and poor family communication are important barriers. Effective interventions incorporate strategies for overcoming barriers, but these have not been broadly tested in clinical settings. Four strategies for reducing CRC in persons with familial risk are suggested: 1) improving the collection and utilization of the FH of cancer, 2) establishing a consensus for screening guidelines by FH, 3) enhancing provider‐patient knowledge of guidelines and communication about CRC risk, and 4) encouraging survivors to promote screening within their families and partnering with existing screening programs to expand their reach to high‐risk groups. Cancer 2016.

The Family Health Promotion Project (FHPP): Design and baseline data from a randomized trial to increase colonoscopy screening in high risk families ☆

Colorectal cancer (CRC) is a significant cause of mortality and morbidity in the United States, much of which could be prevented through adequate screening. Consensus guidelines recommend that high-risk groups initiate screening earlier with colonoscopy and more frequently than average risk persons. However, a large proportion of high risk individuals do not receive regular colonoscopic screening. The Family Health Promotion Project (FHPP) is a randomized-controlled trial to test the effectiveness of a telephone-based counseling intervention to increase adherence to risk-appropriate colonoscopy screening in high risk individuals. Unaffected members of CRC families from two national cancer family registries were enrolled (n=632) and randomized to receive either a single session telephone counseling intervention using Motivational Interviewing techniques or a minimal mail-out intervention. The primary endpoint, rate of colonoscopy screening, was assessed at 6, 12 and 24 months post-enrollment. In this paper, we describe the research design and telephone counseling intervention of the FHPP trial, and report baseline data obtained from the two high risk cohorts recruited into this trial. Results obtained at baseline confirm the need for interventions to promote colonoscopy screening among these high risk individuals, as well as highlighting several key opportunities for intervention, including increasing knowledge about risk-appropriate screening guidelines, and providing both tailored risk information and barriers counseling.

NCCN guidelines® insights: Genetic/Familial High-Risk Assessment: Colorectal, version 3.2017 featured updates to the NCCN Guidelines

The NCCN Guidelines for Genetic/Familial High-Risk Assessment: Colorectal provide recommendations for the management of patients with high-risk syndromes associated with an increased risk of colorectal cancer (CRC). The NCCN Panel for Genetic/Familial High-Risk Assessment: Colorectal meets at least annually to assess comments from reviewers within their institutions, examine relevant data, and reevaluate and update their recommendations. These NCCN Guidelines Insights focus on genes newly associated with CRC risk on multigene panels, the associated evidence, and currently recommended management strategies.

The impact of the rising colorectal cancer incidence in young adults on the optimal age to start screening: Microsimulation analysis I to inform the American Cancer Society colorectal cancer screening guideline: Young-Onset CRC: Screening Implications

In 2016, the Microsimulation Screening Analysis‐Colon (MISCAN‐Colon) model was used to inform the US Preventive Services Task Force colorectal cancer (CRC) screening guidelines. In this study, 1 of 2 microsimulation analyses to inform the update of the American Cancer Society CRC screening guideline, the authors re‐evaluated the optimal screening strategies in light of the increase in CRC diagnosed in young adults.