Stomach cancer screening
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Parminder Dhingra, M.D. [2]
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Overview
Screening cancer
SCREENING MODALITIES
The two main modalities for gastric cancer screening are upper endoscopy and contrast radiography.
Upper endoscopy
Upper endoscopy allows for direct visualization of the gastric mucosa and for biopsies to be obtained for diagnosing precancerous lesions such as gastric atrophy, intestinal metaplasia, or gastric dysplasia in addition to gastric cancer. Although it is more invasive and has a higher cost, upper endoscopy is also more sensitive for diagnosing a variety of gastric lesions as compared with alternative diagnostic strategies.
Contrast radiography
Double-contrast barium radiographs with photofluorography or digital radiography can identify malignant gastric ulcers, infiltrating lesions, and some early gastric cancers. However, false-negative barium studies can occur in as many as 50 percent of cases [3]. In early gastric cancer, the sensitivity of a barium study may be as low as 14 percent [4]. The one scenario in which a barium study may be superior to upper endoscopy is in patients with linitis plastica. The decreased distensibility of the stiff, "leather-flask" appearing stomach is more obvious on the radiographic study, and the endoscopic appearance may be relatively normal.
COMPARISON OF SCREENING METHODS
Test performance
studies suggest that endoscopic screening may be a more sensitive test for screening for gastric cancer [17-21].
A population-based study in South Korea included 2,690,731 individuals who underwent screening for gastric cancer with either upper endoscopy or an upper gastrointestinal (GI) series [22].
Gastric cancer detection rates were 2.61 and 0.68 per 1000 screenings, respectively. The sensitivity rates for upper endoscopy versus upper GI series in detecting gastric cancer were 69 and 37 percent, respectively. Both studies had a specificity of 96 percent. The sensitivity of upper endoscopy in detecting a localized gastric cancer was also significantly higher as compared with upper GI series (68 versus 32 percent). In total, 2067 interval cancers occurred within one year of a negative upper GI series and 1083 cancers occurred after a negative upper endoscopy, but there was no difference in interval cancer rates (1.2 per 1000 screenings for both groups).
Effectiveness
Although some observational studies suggest that screening in areas of high gastric cancer incidence has contributed to the detection of cancer in early stages and an overall decline in gastric cancer mortality, there are no data from large randomized trials demonstrating lower gastric cancer-related mortality in screened populations [17,23-30]. In addition, lead time bias, length bias, and selection bias must be considered when appraising the overall effectiveness of screening demonstrated in observational studies. In a retrospective cohort study of 19,168 gastric cancer patients in Korea, endoscopy-screened patients and patients screened with upper GI series were significantly more likely to be diagnosed with localized gastric cancer as compared with never-screened patients (odds ratio 2.1, 95% CI 1.9-2.3 and 1.2, 95% CI 1.1-1.4, respectively) [30]. However, this study did not include data as to which patients were symptomatic or had undergone evaluation outside of the screening program for evaluation of symptoms.
Screening for gastric cancer may be cost-effective for high-risk subgroups, but not low-risk populations [31,32]. A cost-effectiveness analysis found that in a high-risk group of Chinese men ages 50 to 70 years (standardized incidence of gastric cancer of 25.9 per 100,000 population), screening with upper endoscopy every two years was highly cost-effective ($28,836 per quality-adjusted life-years saved [31]). By contrast, averting one gastric cancer death in men in the United States, assuming an incidence of gastric cancer of <10 per 100,000 population, would cost approximately $247,600, which does not compare favorably with other generally accepted cancer screening interventions
SCREENING STRATEGIES
Universal screening
Universal or population-based screening for gastric cancer has been implemented in some countries with a high incidence of gastric cancer (eg, Japan, Korea, Venezuela, and Chile) [17-19]. However, the recommended screening modality and intervals vary. As examples:
In Japan, population-based screening for gastric cancer is recommended for individuals older than 50 years with conventional double-contrast barium radiograph with photofluorography every year or upper endoscopy every two to three years [20,33,34].
In Korea, upper endoscopy is recommended every two years for individuals aged 40 to 75 years [34-36].
The optimal interval for screening has not been established in randomized trials. A two-year interscreen interval is supported by at least one study that evaluated the mean sojourn time (MST) for gastric cancer (ie, the asymptomatic period during which a cancer can be detected through screening tests before typical symptoms develop) in a cohort of 61,000 Korean men voluntarily attending a cancer screening program and rescreened by endoscopy [37]. A total of 91 incident cases were found during 19,598,598 person-years of follow-up, and the MST for gastric cancer was 2.4 years (95% CI 1.9-3.0). Of note, the MST was shorter in individuals 40 to 49 years of age (1.3 years, 95% CI 1.0-1.7) than the MST in those 50 to 59 years of age or 60 to 69 (3.2 and 3.7, respectively).
At least some data suggest that the screening interval may be widened to a three-year rather than a two-year interval without significantly decreasing the proportion of gastric neoplasms that can be adequately treated by endoscopic methods [38-40]. However, intervals longer than three years may be associated with a greater risk of more advanced stage cancer at diagnosis. As an example, in a retrospective cohort study of 2485 patients with gastric adenocarcinoma in Korea, as compared with individuals who underwent annual screening for gastric cancer, the risk of advanced cancer was higher in individuals who underwent screening at four- or five-year intervals (four-year interval odds ratio [OR] 2.5, 95% CI 1.4-4.5, five-year interval OR 2.2, 95% CI 1.3-3.7), but not in individuals who underwent screening at two- or three-year intervals [38]. In subgroup analysis, individuals with a family history of gastric cancer and individuals in their 60s were more likely to be diagnosed with a higher stage of gastric cancer if upper endoscopies were performed every three years as compared with annually (family history of gastric cancer OR 2.68, 95% CI 1.3-5.7, gastric cancer in 60s OR 2.09, 95% CI 1.0-4.3).
Selective screening of high-risk subgroups
In areas of low gastric cancer incidence, screening for gastric cancer with upper endoscopy should be reserved for specific high-risk subgroups [41-52]. The intensity of screening should be based upon an appraisal of the magnitude of risk in each patient, their suitability for treatment should a lesion be detected, and their willingness to accept the uncertain benefits and risks of a screening program.
Individuals at increased risk for gastric cancer include those with the following:
●Gastric adenomas
●Pernicious anemia
●Gastric intestinal metaplasia
●Familial adenomatous polyposis
●Lynch syndrome
●Peutz-Jeghers syndrome
●Juvenile polyposis syndrome