For the analysis, patients were separated out, depending on whether they had the KRAS codon 12 mutation or the KRAS codon 13 mutation.
Patients with the KRAS codon 13 mutation who were treated with cetuximab lived an average of 7.6 months, versus 5.7 months in those with the other mutation. Also, an average of four months transpired before disease progression, versus about two months in the control group, the investigators found.
Those with the KRAS codon 13 mutation didn't respond as well to the drug as people with a normal version of the gene, but they still responded.
While some experts may quibble with the study's methodology -- pooling data from several already-completed trials -- this may be the only way that enough patients with this relatively rare (codon 13) mutation could be collected for a legitimate analysis, Cohen noted.
Maybe 5 percent of patients with metastatic colorectal cancer, which is cancer that has spread, have this particular KRAS mutation, Cohen said.
Not only will more research need to be done before giving cetuximab to people with the codon 13 mutation becomes common practice, but doctors, the cancer network and insurance companies will have to get on board, Cohen noted.
The cost of cetuximab can be $3,000 a week or higher (the treatment is delivered weekly).
"It's a major cost issue," Cohen said.
The U.S. National Cancer Institute has more on treatments for colorectal cancer.
SOURCES: Durado Brooks, M.D., director, colorectal cancer, American Cancer Society, Atlanta; Steven Cohen, M.D., medical oncologist, Fox Chase Cancer Center, Philadelphia; Oct. 27, 2010, Journal of the American Medical Association
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