MedicalResearch.com Interview with:
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Dr. Weinstein[/caption]
Stephanie J. Weinstein, M.S., Ph.D.
Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics
National Cancer Institute, NIH
MedicalResearch.com: What is the background for this study?
Response: Vitamin D, known for its role in maintaining bone health, is hypothesized to lower colorectal cancer risk via several pathways related to cell growth and regulation. Previous prospective studies have reported inconsistent results for whether higher concentrations of circulating 25-hydroxyvitamin D, the accepted measure of vitamin D status, are linked to lower risk of colorectal cancer. The few randomized clinical trials of vitamin D supplementation and colorectal cancer completed thus far have not shown an effect; but study size, relatively short supplementation duration, and only moderate compliance may have contributed to their null findings.
To address inconsistencies in prior studies on vitamin D, and to investigate associations in population subgroups, we harmonized and analyzed participant-level data from over 5,700 colorectal cancer cases who had blood collected before colorectal cancer diagnosis, and 7,100 matched cancer-free controls. Study participants were drawn from 17 prospective cohorts from the United States, Europe, and Asia and were followed for an average of 5.5 years (range: 1 – 25 years). We used a single, widely accepted assay and laboratory for new vitamin D measurements and calibrated existing vitamin D measurements. In the past, substantial differences between assays made it difficult to integrate
vitamin D data from different studies. Our novel calibration approach enabled us to explore risk systematically over the broad range of vitamin D levels seen internationally.
Dr. Lang[/caption]
Dr. Kathryn Lang
VP, Outcomes and Evidence
Guardant Health
MedicalResearch.com: What is the background for this study?
Response: Despite a wide variety of screening methods available and increasing public awareness of the value of early detection, colorectal cancer (CRC) remains a leading cause of cancer-related deaths. However nearly 1 in 3 adults in the United States is not compliant with screening recommendations, with most citing that current screening methods are time consuming, unpleasant (stool-based testing), and in the case of colonoscopy, invasive. A blood-based CRC screening test could improve compliance rates by providing physicians with an opportunistic, in-office screening modality. However, demonstrating the clinical utility of blood-based cell-free circulating tumor DNA (ctDNA) fractions for the detection of cancer in asymptomatic individuals has thus far been challenged by the failure to achieve clinically meaningful sensitivity and specificity thresholds due to significantly lower tumor cell-free free DNA fractions and the increasing relevance of biological confounders.
The multi-modal approach of Guardant Health’s LUNAR-2 assay (genomics, methylation and fragmentomics) coupled with advanced bioinformatic analysis and a focused approach of honing in on the unique signals of CRC has been shown in previously reported cohorts to perform with sensitivity and specificity which satisfies the needs of clinicians in screening for CRC. 
