Can stool test detect GI cancers?

In a prospective study from China, a novel noninvasive stool DNA methylation assay showed promise for the early detection of multiple gastrointestinal (GI) cancers.

“Stool is a promising sample for GI cancer detection because it contains the host’s exfoliated cells and circulating free DNA derived from GI cancer cells,” said the study investigators, led by Dr Li-Yue Sun from the Second Department of Oncology, Guangdong Second Provincial General Hospital, Guangzhou, China.

“Thus, we aimed to develop a sensitive and noninvasive multitarget stool DNA methylation test for early detection and localization of GI cancers,” the researchers said.

The study included 124 individuals with histologically diagnosed GI cancers who have not received treatment (median age 60 years) and 92 healthy controls who have undergone GI cancer-related examinations every 3 years (median age 57 years). Of those who had GI cancers, a majority (n=81) had stage IV disease. [ASCO Breakthrough 2023, poster 41]

In the methylation analysis, about 80 percent of GI cancer patients tested positive, while 96 percent of the healthy controls tested negative.

For each type of GI cancer, the positivity rates were 71 percent for colorectal cancer, 83 percent for gastric cancer, 75 percent for oesophageal cancer, 81 percent for pancreatic cancer, and 91 percent for ampullary cancer.

In the control group, four tested positive for GI cancers, three of which were advanced adenomas.

The use of multiple logistic regression models enhanced the ability of the DNA methylation analysis to accurately detect and determine the location of the GI cancers, yielding a sensitivity of 88 percent for colorectal cancer, 91 percent for gastric cancer, 88 percent for oesophageal cancer, 90 percent for pancreatic cancer, and 95 percent for ampullary cancer.

Promising use of machine learning + genomics

Although there are some liquid biopsies approved for the early detection of colorectal cancer, their applicability does not extend to other GI cancers. Moreover, some tests that may be used for the detection of multiple GI cancers have low sensitivity and no localization, the researchers noted.

“Our findings show that the multitarget stool DNA methylation assay allowed early and accurate detection and identification of tissue of origin of GI cancers,” they said.

“The results of this study demonstrate the promising utility of machine learning applied to genomics for the detection of cancer in the future. These findings will need to be confirmed in a larger, prospective, multicentre study,” commented ASCO Expert Dr Peter Paul Yu from the Palo Alto Medical Foundation, Mountain View, California, US, in a press release. [old-prod.asco.org/about-asco/press-center/news-releases/novel-non-invasive-dna-methylation-assay-shows-promise, accessed August 31, 2023]

The researchers called for further investigation to validate the role of this new assay in cancer surveillance and prognosis.