This article describes the results of a clinical trial—a research study with volunteer patients. The trial tested adding a third drug to a standard two-drug chemotherapy treatment for colorectal cancer. The standard treatment consists of the drugs fluorouracil and leucovorin. It is given to patients after tumor-removal surgery to keep the cancer from coming back (recurrence). In the trial, a third drug called irinotecan was added. The researchers found that stage III patients whose tumors tested positive for a genetic change called CIMP benefitted from the irinotecan addition. Stage III CIMP-negative patients did not.
“When added to the standard chemotherapy treatment — fluorouracil and leucovorin — adjuvant irinotecan therapy improved overall survival rates for patients with the CpG island methylator phenotype (CIMP). CIMP is seen in about 10 to 20 percent of colorectal cancers. Patients with CIMP-negative tumors, however, exhibited significant harm from the addition of irinotecan — overall survival was 68 percent compared with 78 percent for those receiving the standard treatment alone.
“Our results serve as an example that the molecular characterization of individual tumors may help to determine the most appropriate treatment for patients with colon cancer,” said lead study author Stacey Shiovitz, MD, from the department of medicine, University of Washington, Seattle, WA, and the clinical research division of Fred Hutchinson Cancer Research Center, also in Seattle. “Based on our findings, identification of a tumor’s CIMP status should play a greater role in the clinical setting.”