Non-invasive blood test shows 83% sensitivity in detecting colon cancer, offering hope for early diagnosis

Non-invasive blood test shows 83% sensitivity in detecting colon cancer, offering hope for early diagnosis

In a recent study published inThe New England Journal of MedicineA team of scientists from the United States (US) and Canada evaluated the performance of a blood-based testing method that uses cell-free deoxyribonucleic acid (DNA) to screen for colorectal cancer.

background

Colorectal cancer is one of the most common cancers in the adult population of the United States, with the second highest mortality rate and third highest incidence rate.

Although the lifetime risk of the disease is 4%, overall survival depends on early detection of the cancer.

Individuals in whom the cancer is detected early at the localized stage have a 5-year survival rate of 91%, while those in whom the cancer has progressed to the metastatic stage have a 5-year survival rate of 14%.

Leading cancer experts, as well as bodies such as the US Preventive Services Task Force, recommend asymptomatic screening to reduce the incidence and mortality associated with colorectal cancer.

However, despite the various stool-based and direct visualization tests available for colorectal cancer screening, the adherence rate to regular asymptomatic screening is 59%.

In addition, a significant percentage of colorectal cancer-related mortality occurs in people who do not have regular screening procedures. These statistics highlight the need for an easy-to-use method of colorectal cancer screening to improve screening adherence.

About the study

In the present study, scientists evaluated the performance of a blood-based test that screens for colorectal cancer using cell-free DNA.

Their goal was to address the major factors responsible for low adherence rates to colorectal cancer screening, including pain and invasiveness of testing methods, the time required to perform the test, the embarrassment and inconvenience associated with endoscopy, and the lack of proximity to testing providers, among others.

A multicenter, observational, prospective study enrolled eligible individuals at over 200 sites, including endoscopy and primary care centers.

People between the ages of 45 and 84 were eligible for the study if they underwent routine colonoscopy-based screening and were at average risk of colorectal cancer.

Individuals with inflammatory bowel disease, a genetic predisposition to colorectal cancer, or a family history of colorectal cancer or a history of cancer were excluded from the study.

All participants provided a blood sample before colonoscopy. A colonoscopy that included visualization and photographic documentation of the ileocecal valve or appendix opening was considered complete unless visualization was prevented by a large mass or lesion.

The location and size of lesions identified by colonoscopy were noted and the resected lesions were further processed for histopathological analysis.

The blood samples were subjected to cell-free DNA testing to detect genomic alterations, genetic fragmentation and aberrant methylation patterns in the cell-free DNA that are indicative of colorectal cancer.

The two primary outcomes of the study were sensitivity and specificity for colorectal cancer and advanced neoplasia, respectively. The secondary outcome was the sensitivity of the test in detecting advanced precancerous lesions.

Results

The results showed that the blood-based cell-free DNA test had a sensitivity of 83% in detecting colorectal cancer, a specificity of 90% in detecting advanced neoplasms, and only a sensitivity of 13% in detecting advanced precancerous lesions. The test also had a 10% false positive rate in detecting neoplasms.

Despite the high diversity of the study population in terms of race and ethnicity, the test's performance showed no significant differences, suggesting that it performed equally across all subgroups. However, age was a factor that inversely affected the specificity of the assay, possibly due to age-specific cell-free DNA methylation signals.

The sensitivity for detecting colorectal cancer of this blood-based cell-free DNA test was higher than that of the fecal immunohistochemical test (67.3%) but lower than that of the multitarget stool DNA test (93.9%).

However, the sensitivity of the blood-based test was lowest in detecting advanced precancerous lesions compared to tests such as the methylated Septin9 test, the fecal immunohistochemistry test, and the multitarget stool DNA test.

In addition, the sensitivity of the test also differed depending on the clinical stage of the colorectal cancer, with a sensitivity of 55% for stage I cancer and a sensitivity of 81% for colorectal cancer in stages I to III.

Conclusions

In summary, the study found that a blood-based test for the detection of colorectal cancer using cell-free DNA had a sensitivity of 83% in detecting colorectal cancer, which was higher than that of stool-based immunohistochemical tests but lower than that of stool-based DNA tests.

However, the test's sensitivity in detecting advanced precancerous lesions was lower than any other method.

Although the blood-based test represents a rapid, relatively painless, and noninvasive method of screening for colorectal cancer, these results suggest that further research in larger study populations is needed to improve the test's sensitivity and specificity.

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