October 17, 2012

AACR: New noninvasive colorectal CA screen promising

HealthDay News -- A new noninvasive test for colorectal cancer screening has demonstrated high sensitivity, particularly for precancers that are likely to develop into colorectal cancers, according to data presented at the 11th Annual AACR International Conference on Frontiers in Cancer Prevention Research.

The multitarget stool DNA-based test (sDNA-MT) consists of exfoliated DNA markers and fecal hemoglobin, Graham P. Lidgard, PhD, from Exact Sciences Corporation in Madison, Wis., explained.

“This test measures different kinds of DNA changes, known as methylation and mutation, along with a measure of fecal blood. By combining these measures, we can look for the kinds of biological changes that are most frequently found in precancers and cancers in the colon,” Ligard said in a press release.

He and colleagues used an optimized automated analytic platform and logistic algorithm to assess the performance of sDNA-MT among 1,003 patients patients from 36 study sites, including 796 control patients with negative colonoscopies or small polyps, and 207 patients with confirmed colorectal cancer or dysplasia.

Stool specimens were collected either before colonoscopy bowel preparation in screening and surveillance patients or at least seven days post-colonoscopy from patients with colorectal cancer and large precancers.

The test detected 98% of all cancers as well as 83% of precursors with high-grade dysplasia and 57% of precursors 1 cm or larger overall (advanced adenoma or sessile serrate adenoma), at 90% nominal specificity.

"We are encouraged by the results of this study for detecting cancer and cancer precursors, especially the precursor lesions with high-grade dysplasia, an abnormality broadly recognized as being associated with a higher risk for progression to cancer itself," Lidgard said.

A larger study to assess the sDNA-MT involving stool samples from more than 10,000 patients prior to screening colonoscopy is currently ongoing, after which Exact Sciences plans to seek FDA approval for the test.