New Development in Colon Cancer Treatment

Now a tailored drug therapy may be determined in advance for some cancer patients, depending on whether or not they have a certain K-ras gene. New studies show that patients with colon cancer, who have the normal version of the K-ras gene, responded better to treatment when the drug Erbitux was combined with chemotherapy than did patients on chemo alone. However, patients with the mutated K-ras gene gained no benefits by adding the drug to treatment.

Erbitux, already approved for treating certain cancers, is a monoclonal antibody that blocks the effects of a protein called epidermal growth factor (EGFR) that fuels tumor growth. Noting that therapies like Erbitux typically cost upwards of $5,000, predetermining a patient's genetics may not only help save lives, but would spare them thousands in medical cost and side effects of unnecessary treatment. However, the side effects of Erbitux were reported manageable with the main one being an acne-like rash affecting a small percent of patients on combo therapy.

The international research, lead by Eric van Cutsem, MD, Ph.D., of the University Hospital Gasthuisberg in Leuven, Belgium, studied tumor samples from 587 patients with newly diagnosed colorectal cancer that had already spread to other parts of the body. About two-thirds of the patients showed normal versions of the K-ras gene and Van Cutsem recommended that the gene test, which is readily available, be routinely performed on patients with colon cancer as soon as they are diagnosed.

The study reported that in 59.3 percent of patients with normal K-ras gene, tumors shrank by more than half in response to combination treatment, while only 43.2 percent on chemo showed a decrease in tumor size. At the end of one year, 43 percent receiving combination therapy showed progression-free survival, compared to 25 percent receiving chemotherapy alone. Although no differences were reported in the response rates among those with the mutated K-ras genes, those with normal genes showed a 32 percent less chance of cancer progression.

The bottom line here is that prior to treating colon cancers, doctors and clinics will be able to test patients to see which method of treatment would benefit the patient the most; Erbitux drug therapy combined with chemo for normal genes or chemotherapy alone for patients with mutated K-ras genes.
The findings of this study were presented to the American Society of Clinical Oncology at its annual meeting.