What is the initial test to rule out colorectal cancer (CRC) in a 70-year-old patient presenting with sudden abdominal tenderness and low hemoglobin (HB) level, despite normal abdominal ultrasound (U/S) and physical examination?

From the Guidelines

The initial test to rule out colorectal cancer in a 70-year-old patient with sudden abdominal tenderness and low hemoglobin, despite normal abdominal ultrasound and physical examination, should be a colonoscopy. This procedure allows direct visualization of the entire colon and rectum, enabling detection of cancerous lesions, polyps, or other sources of bleeding that might explain the patient's symptoms and laboratory findings. According to the most recent guidelines from the U.S. Multi-Society Task Force on Colorectal Cancer 1, colonoscopy every 10 years is considered a first-tier test for screening, along with annual FIT. The patient's age (70) places them in a high-risk category for colorectal cancer, and the combination of abdominal tenderness with anemia strongly suggests a gastrointestinal source of blood loss. While fecal occult blood testing or fecal immunochemical testing might be considered as preliminary screening tools, the clinical presentation warrants a more definitive examination. Prior to colonoscopy, the patient should undergo bowel preparation according to standard protocols, and arrangements should be made for sedation during the procedure to ensure patient comfort and optimal examination conditions.

Some key points to consider:

• The American College of Physicians recommends screening for colorectal cancer in asymptomatic average-risk adults between the ages of 50 and 75 years, with the selection of the screening test based on a discussion of benefits, harms, costs, availability, frequency, and patient preferences 1.
• The U.S. Preventive Services Task Force also recommends screening for colorectal cancer in adults aged 50 to 75 years, with the decision to screen in adults aged 76 to 85 years being an individual one, considering the patient's health status, life expectancy, and prior screening history 1.
• A study published in the Annals of Internal Medicine in 2019 provides a guidance statement from the American College of Physicians on screening for colorectal cancer in asymptomatic average-risk adults, recommending colonoscopy every 10 years as one of the screening options 1.

Overall, given the patient's symptoms and age, colonoscopy is the most appropriate initial test to rule out colorectal cancer, as it provides a direct visualization of the colon and rectum, allowing for both diagnostic evaluation and potential therapeutic intervention.

From the Research

Initial Test to Rule Out Colorectal Cancer (CRC)

The initial test to rule out CRC in a 70-year-old patient presenting with sudden abdominal tenderness and low hemoglobin (HB) level, despite normal abdominal ultrasound (U/S) and physical examination, can be determined based on the available evidence.

• The patient's age and symptoms suggest the need for a reliable screening method for CRC.
• According to 2, noninvasive testing provides a safe initial test, and fecal immunochemical test (FIT) is a commonly used noninvasive modality for CRC screening.
• Studies 3, 4, 5, 6 support the use of FIT as an initial screening test for CRC, highlighting its advantages, including better sensitivity for hemoglobin and the ability to screen using only 1 stool sample per cycle.
• Given the patient's low HB level, FIT is a suitable initial test to rule out CRC, as it can detect occult blood in the stool, which may indicate the presence of CRC or other gastrointestinal disorders.

Comparison of Screening Options

• Option A: Occult stool by FIT is a noninvasive and relatively inexpensive test that can be used as an initial screening method for CRC.
• Option B: Endoscopy and colonoscopy are more invasive and are typically used as diagnostic tools after a positive screening test or in patients with high-risk symptoms.
• Option C: Abdominal CT is not a primary screening test for CRC and is usually used to evaluate the extent of disease in patients with a confirmed diagnosis of CRC.

Recommendation

Based on the available evidence, the initial test to rule out CRC in this patient would be Option A: Occult stool by FIT, as it is a noninvasive, safe, and relatively inexpensive test that can provide valuable information about the presence of occult blood in the stool. If the FIT result is positive, further diagnostic testing, such as colonoscopy, may be necessary to confirm the diagnosis of CRC.