December 25, 2014 | by Tami Dennis
The ability to see inside the body will play an increasingly, perhaps surprisingly, important role in the treatment of stomach cancer, or gastric cancer, in the months ahead, with City of Hope researchers exploring the potential of two imaging methods – each with its own unique benefits.
One imaging study will assess the ability of PET scans and Herceptin, a drug best known for treating breast cancer, to guide the treatment of stomach cancer. The other study will use CT scans to determine the stage of cancer ahead of surgery.
Recent clinical trials of chemotherapy plus Herceptin (trastuzumab), which interferes with the spread of cancer cells, suggest that the combination improves survival for some patients with advanced stomach cancer.
Currently, the drug is approved only for those patients whose tumors show an abundance of the HER2 protein. The HER2 protein is associated primarily with breast cancer and ovarian cancer, but it can be found in other cancers as well, including some gastric cancers. HER2-positive cancers are more likely to spread, and spread quickly, than other types of cancers.
But the drug might help other patients as well. Joseph Kim, M.D., head of Upper GI Surgery at City of Hope and a specialist in gastric cancer, points to studies showing that trastuzumab benefits patients whose tumors are negative for HER2 by conventional tests, suggesting that the current methods used to assess HER2 may be insufficient to accurately identify patients eligible for trastuzumab therapy.
He and his colleagues have developed a novel imaging method to better assess which patients might benefit from trastuzumab, and they’re currently conducting a clinical trial to prove their imaging method’s effectiveness. Their technique relies on a specialized copper molecule that can be detected by PET (postitron emmission tomography) scan, along with trastuzumab, which specifically binds to HER2-expressing tissues in the body.
The results of the PET scan imaging will be compared with the patients’ conventional HER2 testing results in order to determine whether the imaging method improves HER2 detection. Improved detection could increase the number of gastric cancer patients eligible for trastuzumab therapy and significantly improve treatment of gastric cancer.
He and his colleagues are currently enrolling patients in their study, known as the 64Cu-DOTA-Trastuzumab study.
In the United States, doctors often use endoscopic ultrasound to determine the stage of stomach cancer tumors and their surrounding lymph nodes, relying on computed tomography (CT) scans to detect spread of the disease in other parts of the body. But a specific type of CT scan, known as CT gastrography with 3-D reconstruction, could open up new doors for gastric cancer specialists.
This specialized form of CT scan, in which patients consume effervescent granules to expand the stomach, allows multiple images from multiple angles. This helps doctors better visualize the various areas of the stomach, as well as the rest of the abdomen and pelvis.
CT gastrography is more commonly used in Asian countries, where the rates of stomach cancer are higher, but City of Hope researchers believe it has potential here as well. “Our pilot study shows that CT gastrography appears to be as good at endoscopic ultrasound in detecting T2 gastric cancers,” Kim said. A T2 cancer is a tumor that has grown into the muscle layer of the stomach.
Although CT gastrography may have limited use in detecting early stomach cancer, it was more effective than endoscopic ultrasound at diagnosing lymph node involvement and distant spread, potentially saving some patients an additional preoperative staging test.
The gastric cancer team continues to evaluate CT gastrography as a staging tool and as a method of periodically assessing patients for cancer recurrence after surgery. “As the number of patients undergoing CT gastrography at City of Hope increases, we hope to update our initial pilot study results and better understand how the use of this technology will fit into clinical practice,” Kim said.
Sayeh Hirmand contributed to this report.
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