LYNDHURST, N.J. -- A study published in the journal CANCER found that InSure,® a fecal immunochemical test (FIT) from Quest Diagnostics Incorporated detected three times as many early-stage colorectal cancers and nearly twice as many significant (pre- cancerous) adenomas compared to Hemoccult II Sensa®1, the traditional guaiac fecal occult blood test.2
In the study published in CANCER, individuals sampled consecutive stools, at home, to complete both the InSure and the Hemoccult II Sensa tests. Study groups included a screening cohort (n=2,351) and a symptomatic diagnostic cohort (n=161). Patients with positive screening results were referred for colonoscopy to detect possible cancer or a significant adenoma. Following colonoscopy, the cancer and type of polyp were subsequently confirmed by histopathology. The InSure FIT demonstrated a true-positive result significantly more often in the presence of cancer (n=24, 87.5 percent vs. 54.2 percent) or significant adenoma (n=61, 42.6 percent vs. 23.0 percent) than did Hemoccult II Sensa. Of all stage I cancers (where the tumor is limited to the lining of the bowel wall), the InSure FIT was positive in 12 of 13 cases, compared to only 4 of 13 with the Hemoccult II Sensa (p=0.002). The study results also showed that the InSure test is more capable than the Hemoccult II Sensa in detecting lower gastrointestinal bleeding in early-stage lesions or significant adenomas.
The InSure test had a marginally higher false-positive rate than did Hemoccult II Sensa (3.4 percent vs. 2.5 percent, respectively). This difference was due to detection of non-neoplastic pathologies, which when excluded the difference in false-positive rates became statistically insignificant (1.2 percent vs. 1.3 percent, respectively for the InSure and Hemoccult II Sensa tests).
"Early detection of significant adenomas and their removal should lead to a decrease in the number of people who will develop colorectal cancer," said Graeme P. Young, MD, FRACP, professor of gastroenterology, department of medicine, Flinders University of South Australia, where the study was conducted. "Importantly, this technology also has distinct behavioral advantages. People are more likely to complete and return the test owing to its simpler sampling procedure and reduced number of samplings."
Colorectal cancer is the second leading cause of cancer death in the United States. According to American Cancer Society (ACS) estimates, of the approximately 55,000 people expected to die from colorectal cancer this year, appropriate screening could save more than half. Patients with colorectal cancer detected in its earliest stage have a 90 percent chance of 5-year survival. ACS's latest guidelines for annual colorectal cancer screening include an option for an annual fecal immunochemical test or fecal occult blood test for people at average risk, 50 years of age and older.
"This is an important finding in the battle against colorectal cancer where early detection is critical," said Joyce G. Schwartz, MD, vice president and chief laboratory officer, Quest Diagnostics. "Since we began offering the InSure test, we've seen more doctors recommending it to patients, most likely because of the test's patient-friendly sample collection features."
About InSure
InSure FIT is a test that uses anti-human hemoglobin antibodies that are highly specific to human globin, the primary protein in blood that is released in stool when cancer and significant pre-cancerous adenomas are present in the colon and rectum. In contrast, guaiac-based fecal occult blood tests detect peroxidase activity of heme -- the part of hemoglobin that contains iron -- in feces; dietary peroxidases and heme from red meat may cause false positives.
Quest Diagnostics is the only laboratory to offer the InSure Fecal Immunochemical Test, an FDA-cleared test for use in screening for sources of lower gastrointestinal bleeding. The InSure test has features that increase the likelihood people will use the tests and return specimens. Among those features:
-- No unpleasant fecal collection and smearing is required. The InSure test utilizes a patented long-handled brush to gently brush the surface of the stool and collect the surrounding toilet water to dab onto the collection card, whereas the standard guaiac-based fecal occult blood test requires a wooden spatula collection of the stool sample that is completely clear of toilet water to be smeared on a test card.
-- Only two specimens are required from consecutive bowel movements, compared to traditional Hemoccult II Sensa, which require six specimens from three bowel movements for analysis.
The study published in CANCER was funded by grants from the National Health and Medical Research Council of Australia and Enterix Australia Pty. Ltd. Enterix was acquired by Quest Diagnostics in September 2006. Neither company participated in the study's data analysis or influenced conclusions reached.
References
1. Hemoccult II Sensa is a trademark of Beckman Coulter, Inc.
2. Smith, A., Young, G. et al. Comparison of a brush-sampling fecal immunochemical test for hemoglobin with a sensitive guaiac-based fecal occult blood test in detection of colorectal neoplasia. Cancer 2006;107 (9) 2152-59.
Source: Quest Diagnostics Incorporated