Gastric Cancer's Two Tumors

Genomic analysis of gastric cancer confirms two tumor types

(RxWiki News) For many years, people with stomach cancer have all been treated the same. Science didn't know any better. It's now understood that this disease is more complex, a finding that will improve treatment options.

A large-scale genomic study, the first of its kind, has confirmed that gastric cancer has two different types of tumors. Researchers have found that different chemotherapy regimens work better with each type. This finding lays the foundation for more effective treatment of gastric cancers, which are among the most deadly.

"Stomach cancers respond differently to chemotherapy, depending on tumor type."

In the 1960's the Lauren classification test was developed that characterizes the clumping behavior of tumor cells as either "intestinal" or "diffuse." This classification is still used today but falls short in terms of thoroughly describing and classifying gastric cancers, according to Patrick Tan, M.D., Ph.D., associate professor in the Cancer and Stem Cell Biology Program at the Duke-National University of Singapore (Duke-NUS) Graduate Medical School, and senior author of the new study.

Dr. Tan explains that patients respond very differently to gastric cancer treatments, something that has indicated differences in the tumors themselves. Yet, stomach cancer is still being treated with the same "one-size-fits-all" approach, says Tan.

To distinguish tumor differences, Tan and his team examined and analyzed 37 pure gastric cancer cell lines. Two distinct subtypes appeared. In most of the cases (64 percent) the gene profiles fit into the Lauren classifications. In the remaining 36 percent, the genomic subtypes were different.

These findings were validated after analyzing tumor samples from 521 patients with stomach cancer.

What this means, says Dr. Tan, is that scientists now appreciate that the two subtypes have different patterns of molecules and have a better grasp of how the different tumor types respond to chemotherapies.

The intestinal-type tumors respond significantly better to 5-fluorouracil and oxaliplatin chemotherapies, while they resist cisplatin more than diffuse tumors.

Researchers have started a trial to profile the genetic make-up of gastric cancer tumors. Treatments will then be prescribed based on tumor type.

A number of other institutions were involved in this study along with Duke-NUS, including facilities in Singapore, South Korea, Australia, Japan, England and MD Anderson Cancer Center, Houston, Texas.

This research is published in the journal Gastroenterology.

According to the National Cancer Institute, approximately 21,000 people will be diagnosed with stomach cancer this year in the United States, and 10,570 will die from it.

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Review Date: 
August 3, 2011