Ko, also a speaker at the 2011 Oncology Congress, said increasing evidence supports the use of neoadjuvant therapy before surgical resection when treating GI tract cancers. However, there are also some potential disadvantages including delay of a potentially curative surgical resection, treatment-related side effects may weaken the patient before surgery, and obscured surgical pathology may result in inaccurate staging.
The changing treatment paradigm for gastrointestinal tract cancers requires yet another set of new nursing skills. “I think the oncology nurse plays a very important role,” Ko said. Nurses need to be aware of the various side effects of the new agents and counsel their patients on the toxicities. Many new agents have their own unique set of side effects.
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COMBINATION RADIOTHERAPY CHEMOTHERAPY
Phase I/II trials currently underway are investigating stereotactic body radiotherapy (SBRT) and stereotactic ablative radiotherapy (SABR) combined with chemotherapy for treating locally advanced pancreatic cancer. Albert Koong, MD, an associate professor of radiation/oncology at Stanford University, Stanford, California, said preliminary findings suggest these approaches may have advantages over conventional radiation therapy. Koong said SBRT and SABR avoid some toxicities associated with conventional radiation therapy. In addition, these types of radiotherapy reduce the treatment time from 5 to 7 weeks to just 1 week. “We treated about 30 plus patients. So it is relatively early,” Koong said. However, these patients are doing better than patients who underwent conventional therapy.
Koong, who presented Novel Radiation Techniques in the Management of GI Tract Cancers at the 2011 Oncology Congress, said there is an overall general shift toward combining different therapies to manage pancreatic, as well as other GI tract, cancers. Up until just 5 years ago, surgeons removed the tumor and then postoperative treatment was managed by a multidisciplinary team. The new standard of care involves discussing different modalities and in what sequence they should be tried. “Sometimes chemotherapy and radiation are better before surgery than after surgery,” explained Koong. This is true for rectal cancer, and studies are now indicating this is true for some GI cancers, too.
EFFECTS OF GENETICS ON TREATMENT RESPONSE
Stomach cancer has two distinct disease variations based on its genetic makeup, and each responds differently to chemotherapy, according to a new study.3 This study is the first large-scale genomic analysis of gastric cancer to confirm the two discrete tumor types. In addition, these researchers found that a specific chemotherapy regimen is more effective on one tumor type, while a different drug works best on the other.3 “Our study is the first to show that a proposed molecular classification of gastric cancer can identify genomic subtypes that respond differently to therapies, which is crucial in efforts to customize treatments for patients,” explained study investigator Patrick Tan, MD, PhD, associate professor in the Cancer and Stem Cell Biology Program at Duke University, Durham, North Carolina.
The National Cancer Institute (NCI) estimates 21,520 new cases of stomach cancer will be diagnosed in the United States and 10,340 persons will die of the disease in 2011.4 Gastric cancer patients have long had markedly different responses to treatments, suggesting that tumors have underlying differences. Hinting at those differences, a microscopic pathology test developed in the 1960s broadly described how well the tumor cells clumped together, typing them as either “intestinal” or “diffuse.” However, the Lauren classification, an analysis named for the doctor who first described the distinctions, fell short as a reliable prognostic tool.5
“Most gastric cancer patients today are still being treated with a common, ‘one-size-fits-all’ regimen,” said Tan. “One reason for this is that the Lauren classification requires significant gastric cancer experience and there is considerable variation in classifying gastric cancers, even among qualified pathologists.”
But the new genetic findings add greater specificity to the microscopic classifications and, for the first time, provide some guidance with which clinicians can prescribe effective treatments. By establishing a highly accurate definition of tumor subtypes, Tan’s team was able to observe the different responses to chemotherapy. Intestinal-type tumors showed significantly better response to 5-fluorouracil (5-FU) and oxaliplatin (Eloxatin, generics) and were more resistant to cisplatin than diffuse tumors. “The exact mechanistic reasons for this difference are currently unclear, and this is an area that we are actively working on,” said Tan. He and his colleagues have launched a prospective clinical trial where gastric cancer tumors will be genomically profiled, and treatments will be allocated on the basis of the tumor type.
