Pernicious anemia and colorectal cancer risk - A nested case-control study

Prevalence and predictors of colonoscopic findings in patients with autoimmune gastritis

The clinical spectrum of autoimmune gastritis is silent in the early stages of the disease and no specific symptom is related to this entity. Although gastroscopic findings of this entity are well defined, data regarding colonoscopic findings are limited. The aims of this study were to determine the prevalence of colonoscopic findings and to explore factors that might affect these findings. This is a retrospective chart review of patients with autoimmune gastritis (n=240). Data regarding colonoscopic findings, serum gastrin and chromogranin A (CgA) levels and gastric histopathological results were extracted and compared with 550 patients positive for Helicobacter pylori and gastric atrophy. Control subjects had colonoscopy and gastroscopy with biopsies. Colorectal lesions were observed in 64 (26.6%) of patients with autoimmune gastritis and 36 (6.6%) patients had colorectal lesions in the control group (p<0.001). Serum gastrin (OR: 8.59, 95% CI 1.72 to 25.07, p<0.001) and CgA levels (OR: 6.79, 95% CI 0.41 to 27.26, p<0.001) were found as factors affecting the presence of colorectal carcinoma. Serum gastrin and CgA levels were also found as predictors for the presence of colorectal adenomas. There is a higher prevalence of colorectal neoplastic lesions in patients with autoimmune gastritis. Serum gastrin and CgA levels were found to be determinants of colorectal neoplastic lesions observed in patients. In the workup of these patients, serum gastrin and CgA levels may guide physicians for the demonstration of colorectal neoplastic lesions.

Insights into Effects/Risks of Chronic Hypergastrinemia and Lifelong PPI Treatment in Man Based on Studies of Patients with Zollinger-Ellison Syndrome

The use of proton pump inhibitors (PPIs) over the last 30 years has rapidly increased both in the United States and worldwide. PPIs are not only very widely used both for approved indications (peptic ulcer disease, gastroesophageal reflux disease (GERD), Helicobacter pylori eradication regimens, stress ulcer prevention), but are also one of the most frequently off-label used drugs (25–70% of total). An increasing number of patients with moderate to advanced gastroesophageal reflux disease are remaining on PPI indefinitely. Whereas numerous studies show PPIs remain effective and safe, most of these studies are <5 years of duration and little data exist for >10 years of treatment. Recently, based primarily on observational/epidemiological studies, there have been an increasing number of reports raising issues about safety and side-effects with very long-term chronic treatment. Some of these safety issues are related to the possible long-term effects of chronic hypergastrinemia, which occurs in all patients taking chronic PPIs, others are related to the hypo-/achlorhydria that frequently occurs with chronic PPI treatment, and in others the mechanisms are unclear. These issues have raised considerable controversy in large part because of lack of long-term PPI treatment data (>10–20 years). Zollinger–Ellison syndrome (ZES) is caused by ectopic secretion of gastrin from a neuroendocrine tumor resulting in severe acid hypersecretion requiring life-long antisecretory treatment with PPIs, which are the drugs of choice. Because in <30% of patients with ZES, a long-term cure is not possible, these patients have life-long hypergastrinemia and require life-long treatment with PPIs. Therefore, ZES patients have been proposed as a good model of the long-term effects of hypergastrinemia in man as well as the effects/side-effects of very long-term PPI treatment. In this article, the insights from studies on ZES into these controversial issues with pertinence to chronic PPI use in non-ZES patients is reviewed, primarily concentrating on data from the prospective long-term studies of ZES patients at NIH.

Incidence of cancer (other than gastric cancer) in pernicious anaemia: A systematic review with meta-analysis

BACKGROUND

Pernicious anaemia (PA) is associated with increased gastric cancer risk, but the evidence is conflicting regarding the associated risk of other cancers.

AIM

To systematically determine the incidence rates of gastro-intestinal cancers other than gastric cancers (GI-other-than-GC) and non-gastrointestinal cancers (non-GIC) in PA adults, globally and per tumour site, and the risk associated with PA for GI-other than GC and non-GIC.

METHODS

Studies of PA patients reporting the incidence of GI-other-than-GCs and non-GICs were identified with MEDLINE (PubMed)-EMBASE (from first date available to April 2017). A meta-analysis of annual cancer incidence rates was performed. The outcome was the cumulative incidence of GI-other-than-GCs and non-GICs (ratio between the numbers of new cancer cases identified during the follow-up period and the number of PA patients) and the incidence rate expressed as the rate of events-per-time-unit (person-years).

RESULTS

Of 82,257 PA patients, the pooled incidence rates/100 person-years for non-GCs and non-GICs of 0.27 (95% CI:0.16-0.42) and 0.23 (95% CI:0.22-0.25) were calculated by meta-analysis. Compared to the GLOBOCAN data for the general population from the countries of the included studies, the meta-analysis showed an overall relative risk (RR) of cancer in PA of 0.68 (95% CI:0.48-0.95). PA patients had a lower RR of colorectal, breast, liver, oesophageal, lung, thyroid, ovary, non-melanoma skin and kidney cancers but had a higher RR of biliary tract cancer (1.81:1.21-2.70), multiple myeloma (2.83:1.76-4.55), Hodgkin's lymphoma (3.0:1.35-6.68), non-Hodgkin's lymphoma (2.08: 1.58-2.75), and leukaemia (1.56:1.16-2.12).

CONCLUSION

An overall lower RR of cancers-other-than-gastric-cancer in PA patients but an increased RR of biliary tract cancers and haematological malignancies was observed.

Valid and efficient subgroup analyses using nested case-control data

BACKGROUND

It is not uncommon for investigators to conduct further analyses of subgroups, using data collected in a nested case-control design. Since the sampling of the participants is related to the outcome of interest, the data at hand are not a representative sample of the population, and subgroup analyses need to be carefully considered for their validity and interpretation.

METHODS

We performed simulation studies, generating cohorts within the proportional hazards model framework and with covariate coefficients chosen to mimic realistic data and more extreme situations. From the cohorts we sampled nested case-control data and analysed the effect of a binary exposure on a time-to-event outcome in subgroups defined by a covariate (an independent risk factor, a confounder or an effect modifier) and compared the estimates with the corresponding subcohort estimates. Cohort analyses were performed with Cox regression, and nested case-control samples or restricted subsamples were analysed with both conditional logistic regression and weighted Cox regression.

RESULTS

For all studied scenarios, the subgroup analyses provided unbiased estimates of the exposure coefficients, with conditional logistic regression being less efficient than the weighted Cox regression.

CONCLUSIONS

For the study of a subpopulation, analysis of the corresponding subgroup of individuals sampled in a nested case-control design provides an unbiased estimate of the effect of exposure, regardless of whether the variable used to define the subgroup is a confounder, effect modifier or independent risk factor. Weighted Cox regression provides more efficient estimates than conditional logistic regression.

Emerging hazard effects of proton pump inhibitor on the risk of colorectal cancer in low-risk populations: A Korean nationwide prospective cohort study

Purpose

Despite plausible mechanisms, the clinical significance of long-term proton pump inhibitor (PPI) use to colorectal cancer (CRC) remains unknown. The purpose of this study was to investigate the association between PPI use and CRC development.

Methods

We conducted a population-based prospective cohort study using the Korean nationwide claims database merged with national health examination data. The study cohort included a total of 451,284 participants who were tracked to identify cases of CRC since 2007. We assessed and standardized PPI use before the index date using the Defined Daily Dose system. We calculated the hazard ratios and their 95% confidence intervals to assess the association between PPI use and CRC occurrence using Cox proportional hazard regression models with adjustment for potential confounders. We performed subgroup analyses of the effect of PPI exposure on CRC development stratified by the CRC risk.

Results

There were 5,304 cases of CRC during the study period of 2,908,152 person-years. PPI use was not associated with CRC risk overall. The incidence of CRC was higher among individuals who were elderly, male, more obese, and drank alcohol more frequently and among those who had more comorbidities. Further subgroup analyses revealed that the hazard effect of PPI use increased linearly in a dose-dependent manner with the number of CRC risk factors for which the risk level was considered low.

Conclusion

Within the low-risk population, PPI use was associated with an increased risk of CRC, although the association did not weigh the effects of conventional risk factors.

Complications of Proton Pump Inhibitor Therapy

Safety issues associated with proton pump inhibitors (PPIs) have recently attracted widespread media and lay attention. Gastroenterologists are frequently asked about the appropriateness of PPI therapy for specific patients. Furthermore, some patients may have had PPI therapy discontinued abruptly or inappropriately due to safety concerns. Faced with such a wide variety of potentially serious adverse consequences, prescribers need to evaluate the evidence objectively to discern the likelihood that any reported association might actually be causal. Here, we review many of the proposed adverse consequences of PPI therapy and apply established criteria for the determination of causation. We also consider the potential contribution of residual confounding in many of the reported studies. Evidence is inadequate to establish causal relationships between PPI therapy and many of the proposed associations. Residual confounding related to study design and the overextrapolation of quantitatively small estimates of effect size have probably led to much of the current controversy about PPI safety. In turn, this has caused unnecessary concern among patients and prescribers. The benefits of PPI therapy for appropriate indications need to be considered, along with the likelihood of the proposed risks. Patients with a proven indication for a PPI should continue to receive it in the lowest effective dose. PPI dose escalation and continued chronic therapy in those unresponsive to initial empiric therapy is discouraged.