A prospective study of esophageal cytological atypia in Linxian county

Screening for oesophageal cancer

BACKGROUND

Oesophageal cancer is a global heath problem. The prognosis for advanced oesophageal cancer is generally unfavourable, but early-stage asymptomatic oesophageal cancer is basically curable and could achieve better survival rates. The two most commonly used tests are cytologic examination and endoscopy with mucosal iodine staining. The efficacy of the screening tests is controversial, and the true benefit and efficacy of screening remains uncertain because of the potential lead-time and length-time biases. This review was conducted to examine the evidence for the efficacy of screening for oesophageal cancer (squamous cell carcinoma and adenocarcinoma).

OBJECTIVES

To determine the efficacy of early screening, using endoscopy with iodine staining or cytologic examination, in reducing mortality from oesophageal cancer in asymptomatic individuals from high-risk and general populations.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 8), The Cochrane Library (2012, Issue 8), MEDLINE (1950 to August 2012), EMBASE (1980 to August 2012), Allied and Complementary Medicine (AMED) (1985 to August 2012), Chinese Biomedical Database (CBM) (January 1975 to August 2012), VIP Database (January 1989 to August 2012), China National Knowledge Infrastructure (CNKI) (January 1979 to August 2012), and the Internet. We also searched reference lists, conference proceedings, and databases of ongoing trials. There was no restriction on language or publication status in the search for trials.

SELECTION CRITERIA

We included only randomised controlled trials (RCT) of screening versus no screening for oesophageal cancer. Randomisation of groups or clusters of individuals was acceptable.

DATA COLLECTION AND ANALYSIS

Two review authors independently scanned the titles and abstracts from the initial search for potential trials for inclusion. We did not find any trials that met the inclusion criteria.

MAIN RESULTS

The electronic search identified 3482 studies. Two authors independently reviewed the references. The reports of 18 studies were retrieved for further investigation. None met the eligibility criteria for a RCT investigation of the effects of screening versus no screening for oesophageal cancer.

AUTHORS' CONCLUSIONS

There were no RCTs that determined the efficacy of screening for oesophageal cancer. Non-RCTs showed a high incidence and the reported better survival after screening could be caused by selection bias, lead-time and length-time biases. RCTs are needed to determine the efficacy of screening for oesophageal cancer.

Association of the polymorphisms of MTHFR C677T, VDR C352T, and MPO G463A with risk for esophageal squamous cell dysplasia and carcinoma

BACKGROUND

From January 2004 to December 2006 a program of endoscopic screening for esophageal lesions was carried out in the high incidence area of esophageal cancer in Feicheng County, China. It provided the samples to evaluate the association of polymorphisms of methylenetetrahydrofolate reductase (MTHFR) C677T, vitamin D receptor (VDR) C352T, and myeloperoxidase (MPO) G463A genotypes with esophageal squamous cell dysplasia and carcinoma.

METHODS

The subjects in the study were divided into 127 dysplasia cases, 126 squamous cell carcinoma cases, and 169 normal controls. Analyses of the MTHFR C677T, VDR C352T, and MPO G463A genotypes were performed using the PCR-restriction fragment length polymorphism (RFLP) method, whereas the multinomial logistic regression model was used in the data analysis to assess the odds ratios (ORs) related to dysplasia and carcinoma.

RESULTS

Compared with the CC genotype of MTHFR C677T, the TT/TC of the genotype significantly increased the risk of the esophageal squamous cells dysplasia [OR, 2.25; 95% confidence interval (CI), 1.18-4.31]; the OR of esophageal squamous cancer was 1.58 (95% CI, 0.85-2.97) after adjustments for age, sex, and years of education. There was an interaction between the TT/TC genotype and alcohol drinking, smoking, and family history of esophageal cancer in the risk of esophageal dysplasia and carcinoma.

CONCLUSIONS

Neither the VDR C352T nor the MPO G463A genotype had manifested association with the dysplasia and carcinoma of the disease, whereas the MTHFR 677TT genotype may be a genetic risk factor for esophageal dysplasia and carcinoma.

Carcinogens and endemic squamous cancer of the oesophagus in Transkei, South Africa. Environmental initiation is the dominant factor; tobacco or other carcinogens of low potency or concentration are sufficient for carcinogenesis in the predisposed mucosa

Oesophageal cancer is common in Africa, and is a major cause of death in Transkei, South Africa. The cause of this endemic disease has been debated for many decades. A continuing focus of research has been identification of a single potent carcinogen. I argue that endemic incidence of oesophageal cancer is associated with potent initiation, not with potent carcinogenesis. Tobacco is a known oesophageal carcinogen, and there is very strong evidence that it is causally involved in a significant proportion of victims. Other potential carcinogens present in the environment include fungal mycotoxins, human papillomavirus, Solanum nigrum and nitrosamines. These are all of lower carcinogenic potential for the oesophagus, and do not have strong evidence associating them with the disease. In the presence of potent environmental initiation, any oesophageal carcinogen even if of low potency or of low concentration may cause the disease. Any or all of the substances named above may be involved, any one of them the cause of the final carcinogenic change in the individual. Tobacco exemplifies this point. It is of relatively low concentration/usage in Transkei, yet has an undeniable association with oesophageal cancer. Carcinogenesis for the oesophagus in Transkei is solely or predominantly due to agents which are already known, including tobacco, acting on a predisposed mucosa. The search for further carcinogens is of low importance, and the search for a single potent carcinogen is misguided. What is of importance is the development of methods to reduce the risks associated with predisposing factors and with known carcinogens.

Esophageal balloon cytology and subsequent risk of esophageal and gastric-cardia cancer in a high-risk Chinese population

Linxian, China has some of the highest rates of esophageal/gastric cardia cancer in the world. In 1983, esophageal balloon cytology screening was performed in 3 communes in northern Linxian. Of the participants, 10,066 with no evidence of cancer were followed prospectively for 7 1/2 years to evaluate the ability of the initial cytologic diagnoses to identify individuals at increased risk for developing cancer of the esophagus or gastric cardia. A total of 747 incident cases of esophageal or cardia cancer and 322 deaths due to these tumors were identified during the follow-up period and used in this analysis. The risks for esophageal or cardia cancer incidence and mortality increased in parallel with the presumed severity of the 1983 Chinese cytologic diagnoses. After adjusting for potential confounding factors, relative risks for esophageal or cardia cancer incidence, by initial cytologic diagnosis, were normal = 1.00 (reference), hyperplasia = 1.25, dysplasia 1 = 2.20, dysplasia 2 = 4.22 and near-cancer = 5.96. Our results suggest that esophageal balloon cytology, as performed and interpreted in Linxian in 1983, successfully identified individuals at increased risk for developing cancer of the esophagus or gastric cardia.

Cytologic screening for esophageal cancer: results from 12,877 subjects from a high-risk population in China

Linxian, China, has one of the highest esophageal-cancer mortality rates in the world. In 1983, esophageal balloon-cytology screening was performed to identify subjects eligible for 2 nutrition-intervention trials in Linxian; 12,877 subjects had cytology slides which were satisfactory for diagnosis. Of the 12,649 subjects with squamous-cell diagnoses, 31% were normal by Chinese cytologic criteria; 38% showed hyperplasia; 21% showed dysplasia 1; 6% showed dysplasia 2; 2% showed near-cancer; and 2% showed cancer. Of the 1,471 subjects with columnar-cell diagnoses, 31% were normal; 44% showed hyperplasia; 16% showed dysplasia 1; 4% showed dysplasia 2; 2% showed near-cancer; and 3% showed cancer. Squamous dysplasia and cancer were more common among females than males, while columnar dysplasia and cancer showed male predominance. The prevalence of dysplasia and cancer of both cell types increased with age. The prevalence of squamous dysplasia was significantly higher than in earlier balloon-cytology screenings in Linxian, probably reflecting changes in cytologic classification.

Retrospective cohort study of risk-factors for esophageal cancer in Linxian, People's Republic of China

A retrospective cohort study of esophageal (including gastric cardia) cancer was conducted to examine dietary and other potential risk factors in Linxian, a high-risk area in P.R. China. Study subjects were identified based on participation in a cytology examination conducted in 1974. They were interviewed in 1989 to obtain information on esophageal cancer risk-factors and identify new cases and deaths. A total of 1,162 subjects from the analytic cohort of 12,693 were determined to have developed esophageal cancer over the 15-year follow-up period. Results indicate that increased age, male gender, a positive family history, low education level, surface-water use, and pork consumption were the strongest risk factors for esophageal cancer identified in this cohort, while use of corn as a primary staple and infrequent consumption of fresh vegetables also were possible risk factors. Traditional or suspected risk factors for esophageal cancer in this and other populations--smoking and alcohol use, and pickled vegetable and moldy food consumption--were not risk factors in this study. Some variation in risk was seen based on the subject's cytology result from 1974. We conclude that dietary factors appear to play a role in the etiology of esophageal cancer in this high-risk population, but are less important than other constitutional factors such as age, gender, and family history.