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Liquid biopsy shows promise for detecting early-stage colorectal cancer

A new study has found that a test that identifies circulating tumour cells (CTCs) present in the bloodstream can detect colorectal cancer at an early stage, with accuracy ranging from 84 to 88%.

Most prior studies using CTCs have been able to detect late-stage colorectal cancer, and this study is one of the first clinical studies to show that CTCs can be useful for detecting early, more treatable stages of the cancer.

These findings will be presented at the upcoming 2018 ASCO Gastrointestinal Cancers Symposium in San Francisco, California

CTCs break away from the primary tumour and travel into the bloodstream where they can then form new tumours at distant locations.

Collection of CTCs from the blood is one form of “liquid biopsy.”

“Our study is important because there is still some reticence among patients to use stool-based tests or have an invasive exam like colonoscopy to detect colorectal cancer,” said lead study author Wen-Sy Tsai, MD, assistant professor, Linkou Chang Gung Memorial Hospital, Taipei, Taiwan. “Our results may point to a solution for people who are reluctant to get an initial screening colonoscopy or are not compliant in returning stool-based test kits that they get from their doctors.”

This study was conducted at Chang Gung Memorial Hospital, Taoyuan, Taiwan.

The researchers enrolled 620 people over the age of 20 who were coming to the hospital for routine colonoscopies or had a confirmed colorectal cancer diagnosis.

Based on the colonoscopy and biopsy, 438 people were found to have either adenomatous polyps (precancerous growths) or early to late-stage colorectal cancers.

The remaining study participants had no signs of a precancerous growth or colorectal cancer (comparison group).

All 620 enrollees had 2 milliliters (about half a teaspoon) of blood tested for CTC analysis through a routine blood draw.

The blood samples were processed using CMx, an assay that captures rare CTCs -- such as those found in early-stage cancer -- on a lipid-coated chip that mimics human tissue.

The results of these assays were then compared in a blinded analysis with the colonoscopy results.

In prior studies, this assay was found to be able to detect very small numbers of CTCs, even down to the level of one CTC per billion blood cells found in most polyps.

The researchers focused on the specificity of the liquid biopsy test, which is the proportion of healthy individuals correctly identified as not having polyps or cancer.

“We believe our high specificity results are important because a high number of false-positive results would discourage many people who are considering getting screened for colorectal cancer from doing so,” said Tsai.

The specificity values were 97.3%, indicating a very low (less than 3%) probability of a false-positive result.

The study results showed that sensitivity ranged from 77% for detection of CTCs in pre-cancerous lesions, to 87% for stage I-IV cancers.

The researchers also calculated the accuracy of the results, which takes into account both sensitivity and specificity, and found that the accuracy of the test was high and ranged from 84 to 88% between pre-cancerous and cancerous samples.

The accuracy of this test was superior to that of faecal occult blood testing (FOBT).

“Recent surveys have found that over 80% of patients who are reluctant to undergo colonoscopy screening would be receptive to a blood test over stool-based tests,” said co-author Ashish Nimgaonkar, MD, assistant professor of medicine, Johns Hopkins University, Baltimore, Maryland. “A number of studies have found that affordability was the number one reason for not being screened, however this test is highly affordable and can potentially cost less than $100.”

Dr. Nimgaonkar also noted that colonoscopy would still be the gold-standard diagnostic test and would be needed for tumour or polyp sample removal if an individual had a positive CTC test.

The authors are currently planning to validate the use of CTC testing in the general population in Taiwan and to conduct studies in the U.S.

According to the authors, the technology used in this study potentially could be used with other solid tumours, such as breast, lung, and prostate cancer.

Source: ASCO Gastrointestinal Cancers Symposium

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Sergio Stagnaro / 31.01.2018

Despite that the presence of malignant cells in blood demonstrates that cancer is now less or more developed, Liquid Biopsy for detecting early stage colorectal cancer is interesting but expensive methodology, which can not be applied as an initial test on very large scale. Based on my long clinical experience, first of all three clinical signs should be used in all subjects who present themselves for a medical examination: Terziani's Manoeuvre (1), showing elsewhere the presence of Oncological Terrain-Dependent, Inherited Real Risk; Stagnaro's Sign (2), indicating its location in the GIT; Berretti's Signs (3), allowing to localize such a Inherited Real Risk in the colorectal tract.
References.
1) Sergio Stagnaro. Terziani's Maneuvre in early recognizing cancer from its first stage, Inherited Real Risk. www.sisbq.org, http://www.sisbq.org/uploads/5/6/8/7/5687930/terzianimaneuvre.pdf
2) Sergio Stagnaro. Stagnaro’s Sign in detecting every gastrointestinal Disorder, even initial or symptomless. http://www.sisbq.org/uploads/5/6/8/7/5687930/stagnarosign.pdf
3) Sergio Stagnaro. Segno di Berretti: Diagnosi Semeiotica-Biofisica-Quantistica del Cancro Colon-Rettale, ad Iniziare Dal Reale Rischio Congenito. http://www.altrogiornale.org, 9 aprile 2010. http://www.altrogiornale.org/news.php?extend.5983

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