Results of a Population-Based Gastric Cancer Screening Program Conducted in Chile 1996-2008

Abstract

Background Chile presents the second highest stomach cancer (SC) incidence and mortality in the Americas. Since 1980 the SC mortality rate has stabilized at around 20 per 100,000, reaching a level of 18.6 per 100,000 in 2008 (males 24.4, females 12.9). Beginning in 2006 the public and the private health insurance systems cover a secondary prevention program consisting of upper gastrointestinal endoscopy (UGE) for all symptomatic cases (epigastric pain with or without symptoms of poor prognosis) aged 40 and above; it also covers medical and surgical treatments of SC detected. This prevention program has been piloted since 1996 in La Florida County (66,412 beneficiaries 40 years and older). This is the largest SC detection program conducted in Chile so far. Its goals are to decrease SC mortality through early detection and treatment. Our aim is to evaluate the 12 years of experience using this strategy. Methods Patients consulting in the primary care clinics of the study area who satisfied the above mentioned criteria were referred to the secondary level for UGE. Any suspicious lesions at UGE were biopsied and detected SC cases were referred to the base hospital for treatment. We entered all SC patients detected in the screening program from 1996 to 2008. We describe SC cases by sex, age, and staging -TNM classification system-, calculate their 5 year survival rate using the Kaplan Maier method and identify prognostic factors using the Log rank test and Cox model. Results In the study period, 11,978 individuals were referred for UGE 29.7% males (mean age 53.3: 14-93 years) and 70.3% females (mean age 52.2: 14-95 years). We identified 234 SC cases (67.1% males; 32.9% females); mean age of SC patients was 65.7 years (males 65.2 yrs, females 66.9 yrs). Detection rate of SC was 4.4% and 0.9% for males and females respectively (p<0.00001). SC staging for all patients and for males and females were: stage I 39% (35%, 45%), stage II 5% (2%, 12%), stage III 15.8% (15%, 17%), and stage IV 40% (48%, 26%). At the 5-year follow-up, 64 (27.3%) patients remained alive, 132 (56.41%) had died from SC, 12 (5.1%) died from other causes and 26 (11.1%) were censored; the 5-year survival was 41.5% (35.9% and 52.8% for males and females, p=0.002). The only prognostic factors in multivariate analysis were stage (p<0.0001) and age (p=0.001). Discussion The 5-year survival rate for SC in the program (42%) was higher than previously reported in Chile in population-based studies (11%), although the survival range of hospital-based reports has been between12-49%. We needed 212 endoscopies to detect one early cancer. It is necessary to review the current strategy to focus the UGE on populations at higher risk of early cancers -people under 50 years of age-and to include biomarkers to triage the population.