OBJECTIVE: (1) To estimate the prevalence of cancer as an cause of abdominal pain, (2) to identify useful information of history and physical examination, (3) to assess performance of potential screening tests, and (4) to formulate an efficient algorithm for distinguishing patients with cancer.
DESIGN: Prospective observational study.
SETTING: General medical outpatient clinic in a university teaching hospital.
PARTICIPANTS: 470 outpatients (men, 216; women, 254; mean age±standard deviation, 44.6±16.5; age range, 16 to 89) complaining of abdominal pain at their first visits.
MEASUREMENTS AND MAIN RESULTS: A cancer causing abdominal pain was found in 18 patients (3.8%) . These 18 patients with cancer and the remaining 452 patients without cancer were compared regarding clinical findings. Findings significantly more common in patients with cancer were: age of 40 years or over; unexplained weight loss; insidious onset; and duration of pain longer than one preceding month without relief. Among recorded physical findings, countenance reflecting severe pain, fever, and abdominal tenderness were significantly associated with cancer. Elevation of LDH, WBC, CRP, ESR, and CEA were moderately useful discriminators for patients with and without cancer. The logistic regression analysis with complete clinical data set covering history, physical examination and laboratory tests showed that the only findings significantly associated with cancer were unexplained weight loss (odds ratio: 18.9, 95% CI 1.5-20.1), duration of pain over one month (odds ratio: 24.8, 95% CI 1.6-27.9), countenance of severe pain (odds ratio: 159.1, 95% CI 4.5-162.1), and WBC>10, 000 (odds ratio: 22.3, 95% CI 1.1-31.0) .
CONCLUSIONS: Our data support the value of the combined use of history, physical and selected laboratory findings in detecting cancer among patients with abdominal pain. Application of such selected criteria holds the promise of more efficient care with judicious and effective use of endoscopy or sonography without lowering the quality of care.