Gastric Adenocarcinoma Is Typically Diagnosed Using Upper Endoscopy and Managed

question 488

Multiple Choice

Gastric adenocarcinoma is typically diagnosed using upper endoscopy and managed with radical gastrectomy and, in some cases, chemoradiation; nevertheless, long-term survival is poor.  Researchers in a region with a relatively high incidence of gastric adenocarcinoma are evaluating a novel screening test for early detection of the malignancy in high-risk patients.  The novel test is based on the measurement of a recently discovered serologic marker of gastric adenocarcinoma, MGAc.  Based on results of a large study sample of representative high-risk patients screened with MGAc and diagnosed with gastric adenocarcinoma, the mean survival of patients since time of diagnosis is 8.2 months.  A review of records shows that, compared to these patients, similar high-risk patients who were diagnosed using the traditional endoscopic modality had a statistically significant lower mean survival of 7.1 months, with no statistically significant differences in the rates of radical gastrectomy or in the average number or intensity of chemoradiation cycles.  Which of the following best explains these results?

• A)Lead-time bias
• B)Length-time bias
• C)Low sensitivity
• D)Recall bias
• E)Selection bias

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