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Patients carrying at least one of the four key genes show a significantly increased risk for disease recurrence and mortality in gastric cancer, according to new research that potentially paves the way for precision oncology and improved targeting of therapies.

“About a third of patients with gastric cancer in our study had somatic mutations or variants of uncertain significance in [one of] four key genes,” lead author Ulysses Ribeiro, MD, PhD, a professor of digestive system surgery at the University of São Paulo School of Medicine in São Paulo, Brazil, said in a press briefing for the study, presented at Digestive Disease Week (DDW) 2025.

“These patients were more likely to have their cancer come back or to die from the disease, even after surgery and the best chemotherapy and immunotherapy regimens,” said Ribeiro. 

While treatment strategies in gastric cancer have improved in recent years, resistance to multiple drugs continues, and the 5-year overall survival rate remains low — about 36% — underscoring the critical need for targeted therapies.

In an effort to identify genetic alterations that could have prognostic value, Ribeiro and his colleagues used next-generation DNA sequencing to analyze 21 genes in the tumor samples of 87 patients with gastric cancer who had undergone curative surgery and chemotherapy at the Sao Paulo Cancer Institute, São Paulo, Brazil.

Using Cox regression analysis, they found pathogenic variants or variants of uncertain significance in the following four genes: BRCA2, CDH1, RHOA, and TP53. “We found that 33% of patients carried at least one of these four genes,” Ribeiro told Medscape Medical News.

Individually, each of the four genes with pathogenic variants or variants of uncertain significance had significantly or near-significantly higher risks in a survival analysis vs wild-type or benign variants, including BRCA2 (hazard ratio [HR], 4.33; P = .030); CDH1 (HR, 7.54; P = .004); RHOA (HR, 29.24; P < .001); and TP53 (HR, 2.82; P = .07).

A further multivariate analysis adjusting for key confounders showed that, when combined, carriers of the genes had lower disease-free survival (P = .005) and worse overall survival (P = .009) than those with none of the mutations.

“Individually, all four genes were related to prognosis in our gastric cancer patients, and when combined, the genes had even a higher difference in prognosis, varying from 2 to 28 times higher,” Ribeiro said.

Overall, factors such as having a more advanced tumor, node, metastasis stage, pathological stage, and the presence of a pathogenic mutation or a variant of uncertain significance in the four genes in the model were independently associated with worse disease-free survival.

Familiar Genes

Some of these genes are highly familiar. BRCA2 is well-known for its role in increasing the risk for breast and ovarian cancers, and CDH1 is known to be associated with hereditary diffuse gastric cancer, which is the most common hereditary cancer syndrome linked to gastric cancer.

TP53, also known as the “guardian of the genome,” is the most commonly altered gene in human cancers, while RHOA is known to be involved in encoding the GTPase protein RhoA, which is key in the regulation of cell shape, motility, and other essential cellular processes.

“This is the first time that these four genes have been shown to strongly relate to these gastric cancer outcomes,” said Ribeiro. This suggests that there’s more than one pathway by which stomach cancer forms and that some stomach cancers are much more aggressive than others.

He noted that “patients without these high-risk mutations” could be given “less aggressive treatment, in some cases sparing them from unnecessary side effects.”

Speaking during the press briefing, Loren A. Laine, MD, who is a professor of medicine and chief of the Section of Digestive Diseases at the Yale School of Medicine in New Haven, Connecticut, and council chair of DDW 2025, agreed that “certainly, if these genetic factors, along with other factors, predict risk, this also has implications in practice with respect to the level of monitoring during the follow-up and determining the need for therapy.”

In addition, “it will be interesting to see how much this adds to other known risk factors, such as pathologic stage,” said Laine.

A strength of this study, “which I think is unique, is that it looks at a Western population,” whereas data on gastric as well as esophageal cancer is heavily biased to Eastern regions like China and East Asia, where the rates are much higher than in the West, Alia Qureshi, MD, an associate professor of esophageal and gastric cancer surgery at Oregon Health & Science University in Portland, Oregon, told Medscape Medical News.

While noting the limitation of the relatively small sample size, Qureshi said the study is nevertheless “exciting and moving the direction we want to go, specifically towards precision medicine [and] precision oncology.”

The study “builds on existing understanding, especially with regard to TP53 and CDH1, and it points to the opportunity to use this data in a way to direct patient care or possibly therapeutic intervention,” she said.

Laine’s disclosures include consulting and/or relationships with Medtronic, Phathom Pharmaceuticals, Biohaven, Celgene, Intercept Pharmaceuticals, Merck, and Pfizer. Qureshi had no disclosures to report.