The importance of exposure rate on odds ratios by cigarette smoking and alcohol consumption for esophageal adenocarcinoma and squamous cell carcinoma in the Barrett's Esophagus and Esophageal Adenocarcinoma Consortium

Advancing the application of omics-based biomarkers in environmental epidemiology

The use of omics represents a shift in approach for environmental epidemiology and exposure science. In this article, the aspects of the use of omics that will require further development in the near future are discussed, including (a) the underlying causal interpretation and models; (b) the "meet-in-the-middle" concept, with examples; (c) the role of "calibration" of measurements; and (d) the role of life-course epidemiology and the related development of adequate biostatistical models.

Quantitative association of tobacco smoking with the risk of nasopharyngeal carcinoma: a comprehensive meta-analysis of studies conducted between 1979 and 2011

Over the years, many studies have attempted to establish a link between tobacco smoking and an increased risk of nasopharyngeal carcinoma (NPC), but their results have been inconsistent. To clarify this link, we first conducted a comprehensive meta-analysis to integrate the findings of epidemiologic studies from the last half-century. The methodology used for this study followed the checklist proposed by the Meta-analysis of Observational Studies in Epidemiology (MOOSE) Group. Pooled risk estimates were generated using a random-effects model. Twenty-eight case-control studies and 4 cohort studies involving a total of 10,274 NPC cases and 415,266 comparison subjects were included. A substantial effect of smoking on the risk of NPC was identified in this study. The results showed that ever smokers had a 60% greater risk of developing the disease than never smokers (95% confidence interval: 1.38, 1.87); this was a robust dose-dependent association. More importantly, stronger associations were observed in low-risk populations and among persons with the predominant histological type of differentiated NPC than in high-risk populations and persons with an undifferentiated type; the odds ratios were 1.76 and 2.20, respectively, versus 1.29 and 1.27. In this comprehensive meta-analysis, well-established statistical evidence was provided about the role of tobacco smoking in the etiology of NPC.

Oesophageal hyperkeratosis: clinicopathological associations

AIMS

Oesophageal hyperkeratosis is rarely described. In contrast to hyperkeratosis of orolaryngeal mucosa, where its risk factors and association with squamous neoplasia are well-studied, the prevalence and clinicopathological features of oesophageal hyperkeratosis are unknown.

METHODS AND RESULTS

We reviewed prospectively 1845 oesophageal biopsies and found hyperkeratosis in 37 (2.0%). Among 98 patients studied, hyperkeratosis occurred in two distinct settings: group 1 [within Barrett's oesophagus (BO)/adenocarcinoma, n = 61, 62%] and group 2 (outside BO/adenocarcinoma, n = 37, 38%). In contrast to group 1, hyperkeratosis in group 2 was more often multifocal (>3 foci in 51% versus 16%, P = 0.0001), involved mid-oesophagus (51% versus 2%, P < 0.0001), showed endoscopic leucoplakia (24% versus 3%, P = 0.003) and involved current/former alcohol users (51% versus 19%, P = 0.0012). Importantly, invasive squamous carcinoma and squamous dysplasia were seen only in group 2 (47% and 19% versus 0%, P < 0.0001). Further, 42% of group 2, but none of group 1, had benign or malignant squamous lesions of the oral cavity/larynx (P < 0.0001).

CONCLUSION

Hyperkeratosis involves ~2% of oesophageal biopsies and can be divided into cases occurring within BO/adenocarcinoma and those occurring outside BO/adenocarcinoma. The former lack clinical significance, whereas the latter are associated frequently with oesophageal squamous neoplasia and squamous pathology of the head and neck region.

Case-control analysis on metformin and cancer of the esophagus

PURPOSE

Metformin use has been associated with decreased cancer risks, though data on esophageal cancer are scarce. We explored the relation between use of metformin or other anti-diabetic drugs and the risk of esophageal cancer.

METHODS

We conducted a case-control analysis in the UK-based general practice research database (GPRD, now clinical practice research datalink, CPRD). Cases were individuals with an incident diagnosis of esophageal cancer between 1994 and 2010 at age 40-89 years. Ten controls per case were matched on age, sex, calendar time, general practice, and number of years of active history in the GPRD prior to the index date. Various potential confounders including diabetes mellitus, gastro-esophageal reflux, and use of proton-pump inhibitors were evaluated in univariate models, and the final results were adjusted for BMI and smoking. Results are presented as odds ratios (ORs) with 95 % confidence intervals (CI).

RESULTS

Long-term use (≥30 prescriptions) of metformin was not associated with a materially altered risk of esophageal cancer (adj. OR 1.23, 95 % CI 0.92-1.65), nor was long-term use of sulfonylureas (adj. OR 0.93, 95 % CI 0.70-1.23), insulin (adj. OR 0.87, 95 % CI 0.60-1.25), or of thiazolidinediones (adj. OR 0.71, 95 % CI 0.37-1.36).

CONCLUSION

In our population-based study, use of metformin was not associated with an altered risk of esophageal cancer.

Recent developments in esophageal adenocarcinoma

Answer questions and earn CME/CNE Esophageal adenocarcinoma (EAC) is characterized by 6 striking features: increasing incidence, male predominance, lack of preventive measures, opportunities for early detection, demanding surgical therapy and care, and poor prognosis. Reasons for its rapidly increasing incidence include the rising prevalence of gastroesophageal reflux and obesity, combined with the decreasing prevalence of Helicobacter pylori infection. The strong male predominance remains unexplained, but hormonal influence might play an important role. Future prevention might include the treatment of reflux or obesity or chemoprevention with nonsteroidal antiinflammatory drugs or statins, but no evidence-based preventive measures are currently available. Likely future developments include endoscopic screening of better defined high-risk groups for EAC. Individuals with Barrett esophagus might benefit from surveillance, at least those with dysplasia, but screening and surveillance strategies need careful evaluation to be feasible and cost-effective. The surgery for EAC is more extensive than virtually any other standard procedure, and postoperative survival, health-related quality of life, and nutrition need to be improved (eg, by improved treatment, better decision-making, and more individually tailored follow-up). Promising clinical developments include increased survival after preoperative chemoradiotherapy, the potentially reduced impact on health-related quality of life after minimally invasive surgery, and the new endoscopic therapies for dysplastic Barrett esophagus or early EAC. The overall survival rates are improving slightly, but poor prognosis remains a challenge.

A meta-analysis of body mass index and esophageal and gastric cardia adenocarcinoma

BACKGROUND

The incidence rates of esophageal and gastric cardia adenocarcinoma (EGCA) have increased over recent years in several countries, and overweight/obesity has been suggested to play a major role in these trends. In fact, higher body mass index (BMI) has been positively associated with EGCA in several studies.

MATERIAL AND METHODS

We conducted a meta-analysis of case-control and cohort studies on the BMI and EGCA updated to March 2011. We estimated overall relative risks (RRs) and 95% confidence intervals (CI) for BMI between 25 and 30 and BMI ≥ 30 kg/m(2), when compared with normo-weight subjects, using random-effects models.

RESULTS

We identified 22 studies, including almost 8000 EGCA cases. The overall RR was 1.71 (95% CI 1.50-1.96) for BMI between 25 and 30, and was 2.34 (95% CI 1.95-2.81) for BMI ≥ 30 kg/m(2). The continuous RR for an increment of 5 kg/m(2) of BMI was 1.11 (95% CI 1.09-1.14). The association was stronger for esophageal adenocarcinoma (RR for BMI ≥ 30 kg/m(2) = 2.73, 95% CI 2.16-3.46) than for gastric cardia adenocarcinoma (RR for BMI ≥ 30 kg/m(2) = 1.93, 95% CI 1.52-2.45). No substantial differences emerged across strata of sex and geographic areas.

CONCLUSION

Overweight and obesity are strongly related to EGCA, particularly to espophageal adenocarcinoma.