BLUE-C: Next Generation Multi-Target Stool DNA Test for Colorectal Cancer and Advanced Neoplasia

Taha Qazi, MD

Colorectal cancer (CRC) remains the second most common cause of cancer-related death, despite preventative screening and detection strategies.¹ Multiple strategies exist for the screening CRC, ranging from colonoscopy to stool-based testing. Prior studies have suggested that screening for early-stage cancers was curable with reduced mortality.² Unfortunately, adherence to colon cancer screening continues to be below the rate of targeted recommendations.³

Non-invasive screening tests have been developed for the evaluation of colon cancer using stool DNA molecular markers and is currently a part of the colon cancer screening guidelines. In the initial trials, however, the despite having a higher sensitivity than a comparator stool test, the specificity was lower. Recently, a newly developed, multi-target DNA test has been developed for the goal of improving specificity. In the BLUE-C study, the authors aimed to evaluate the test characteristics, sensitivity and specificity of this next-generation stool test for CRC and advanced neoplasia (colorectal cancer or advanced precancerous lesions).⁴

The next generation test includes a new molecular panel, including the methylated DNA markers ceramide synthase 4 gene (LASS4), leucine-rich repeat containing protein 4 gene (LRRC4), serine–threonine protein phosphatase 2A 56-kDa regulatory subunit gamma isoform gene (PPP2R5C), and the reference marker zinc finger DHHC-type containing 1 gene (ZDHHC1), while retaining fecal hemoglobin.

Across 186 sites between 2019-2023, asymptomatic patients aged ≥40 years old undergoing screening colonoscopy were approached for inclusion. Patients with a prior history of CRC, advanced pre-cancerous lesions, a family history or personal history of polyposis conditions were excluded. Patients with a history of inflammatory bowel disease (IBD) or Cronkhite-Canada Syndrome were also excluded. Patient with a prior positive first generation multi-target stool DNA test, a positive fecal immunohistochemical test (FIT) or fecal occult blood test within the previous 6 months of inclusion were also excluded. Symptoms of rectal bleeding were also exclusionary as was a recent colonoscopy within nine years of inclusion.

Patients who were included had stool testing obtained for both FIT and the next-generation multi-target stool DNA test, prior to the provision of preparation. Screening colonoscopy was then performed as standard of care. The primary outcome was the sensitivity of the newer generation, multi-target stool DNA test for CRC, with sensitivity defined as proportion of patients with CRC with a positive test result.Additionally, specificity for advanced neoplasia was defined as the proportion of patients with a negative test result among patients without advanced neoplasia. Advanced precancerous lesions included adenomas and sessile serrated lesions (including large, hyperplastic polyps) that were at least 1 cm in the longest dimension, lesions with villous histologic features, and high-grade dysplasia.

A total of 20,176 participants were included in the study, of which 98 had CRC; 2144 had advanced precancerous lesions; 6973 had non-advanced adenomas; and 10,961 had non-neoplastic findings. The next-generation test had a sensitivity for CRC of 93.9% (95% CI, 87.1 - 97.7), a specificity of advanced neoplasia of 90.6% (95% CI, 90.1 - 91.0).

Sensitivity of advanced pre-cancerous lesions was 43.4% (95% CI, 41.3 - 45.6). Sensitivity for high-grade dysplasia was 74.6% (95% CI, 65.6 - 82.3). Specificity for non-neoplastic lesions or a negative colonoscopy was 92.7% (95% CI, 92.2 - 93.1). In comparison to the FIT testing, the multi-target DNA test had a better sensitivity for CRC and advanced pre-cancerous lesions; however, the specificity was lower for advanced neoplasia with the next-generation multi-target stool DNA test compared to FIT.

The reduction in false positives with the next-generation screening tool may play a pivotal role in appropriate resource and screening allocations. More importantly, this increased specificity did not result in a decreased sensitivity. When analyzing age-related cohorts, the specificity was highest in the next-generation stool testing, (97.3% among those 45 - 49 years old and 95.9% among those 50 - 54 years old). Considering this, the test may role in improving screening adherence, especially in this younger cohort of patients.

A major limitation of the study is the lack of comparison of the next generation multi-target stool DNA test to the current multi-target stool test. A direct comparison of the 2 tests may provide initial insight on the improvement of the next generation multi-target DNA test compared to the currently available multi-target stool test. Despite this fact, the next-generation multi-target stool DNA test provides another avenue for CRC screening which may improve adherence to CRC screening guidelines and improve detection of a preventable CRC and neoplastic lesions.

References

1. ^{Siegel RL, Miller KD, Wagle NS, Jemal A. Cancer statistics, 2023. CA Cancer JClin 2023; 73: 17-48.}
2. ^{Carethers JM. Screening for colorectal cancer in African Americas: Determinatns and Rationale for Earlier Age to Commence Screening. Dig Dis Sci 2015; 60:711-721}
3. ^{American Cancer Society. 80% in every community. National Colorectal Cancer Roundtable (https://nccrt .org/80-in-every-community-2/}
4. ^{Imperiale, T. F., et al. (2024). "Next-Generation Multitarget Stool DNA Test for Colorectal Cancer Screening." New England Journal of Medicine 390(11): 984-993.}