Findings from a 10-year, world-wide study involving 12,834 stage 3 colon cancer patients on adjuvant chemotherapy showed that patients with a lower risk of cancer recurrence who received three months of chemotherapy versus the standard six months of treatment did just as well.
The findings from the IDEA International Duration Evaluation of Adjuvant Chemotherapy Collaboration were presented at the 2017 American Society of Clinical Oncology annual meeting, held June 2-6 in Chicago.
Anthony Shields, M.D., Ph.D., professor of Oncology for the Wayne State University School of Medicine and associate center director of Clinical Sciences for the Barbara Ann Karmanos Cancer Institute, served as co-chair of the North American study.
The findings could change the standard of treatment for many stage 3 colon cancer patients.
"Any time scientists can lower the toxicity for cancer patients and still get the intended results from the treatment, it's exciting news," Dr. Shields said. "For some stage 3 colon cancer patients, six months of chemotherapy will still be the recommendation. However, based on study findings, we estimate that for about 60 percent of patients with low-risk colon cancer, representing approximately 20,000 patients annually in the United States and 400,000 annually worldwide, the same benefits can be achieved with three months of treatment instead of six months, decreasing the side effects and risks, such as nerve damage, that can be attributed to continued chemotherapy."
The IDEA collaboration began in 2007 and remains to date the largest colon cancer study of its kind. The study enrolled 12,834 stage 3 colon cancer patients in six phase 3 trials concurrently worldwide in North America, Europe and Asia, representing 12 countries in total.
The senior study author was Axel Grothey, M.D., an oncologist with the Mayo Clinic Cancer Center in Rochester, Minn. Co-chairing the North American study with Dr. Shields was Jeffrey Meyerhardt, M.D., M.P.H., of the Dana-Farber Cancer Institute and Harvard Medical School.
The study followed patients for a median of 39 months after surgery for stage 3 lymph node-positive colon cancer. Since 2004, the standard (adjuvant) treatment after surgery has been a combination of chemotherapies (FOLFOX or CAPOX), given over a period of six months.
In this study, the patients who were on a three-month treatment were associated with a less than 1 percent lower risk of recurrence compared with a six-month treatment course as measured by the three-year disease-free survival rate (74.6 percent versus 75.5 percent). In a subset of patients categorized as low risk of cancer recurrence (cancer spread to one to three lymph nodes and not completely through the bowel wall), there was almost no disease-free survival difference between a three-month versus six-month course of therapy (83.1 percent versus 83.3 percent).
Dr. Shields and the other scientists involved in the IDEA collaboration are in the process of writing the study results with the goal of having it peered reviewed and formally published.
"We also plan to have the results incorporated into the pathways recommended by our individual cancer centers and organizations," Dr. Shields said.
"Physicians who treat patients with stage 3 colon cancer can discuss study results with their patients now to see if decreasing the length of chemotherapy to three months, or stopping treatments early depending on the treatment schedule, would be appropriate based on the patient's profile and risk," he said. "To be able to offer thousands of stage 3 colon cancer patients less chemotherapy and still get the desired outcome will be welcome news for many patients and their loved ones."