In a nutshell
This study investigated the impact of two genetic mutations (abnormal genes) on progression of colorectal cancer after treatment.
Some background
It is important to determine if a patients with metastatic colorectal cancer (colon or rectal cancer that has spread to distant organs) have a KRAS mutation as it can affect their response to some anti-cancer drugs. Another gene that is known to play a role in colorectal cancer is the BRAF gene. Patients with a mutated BRAF gene also respond less effectively to some cancer treatments.
The value of testing for KRAS and BRAF mutations is less clear in patients with stage II or stage III cancer (the cancer has spread to or through the outer layer of the bowel or to the lymph nodes, but not distant organs). However, it has been suggested that patients with the mutations may have worse survival and a higher risk of cancer progression.
Methods & findings
This study included 437 patients to assess the impact of KRAS and BRAF mutations on patient outcome. All patients had high-risk stage II or stage III colorectal cancer. After curative surgery patients were treated with FOLFOX chemotherapy (5-fluorouracil [Efudex], leucovorin, oxaliplatin [Eloxatin]). Patients’ disease progression was assessed for 3 years.
26.5% of patients had a mutated KRAS gene and 3.7% of patients had a mutated BRAF gene. Three years after surgery 88.2% of patients remained cancer free. Having a mutated BRAF gene did not have any impact on the risk of relapse.
Patients with a KRAS mutation had 2.3 fold higher risk of the cancer relapsing, compared to patients with a normal KRAS gene. After 3 years 21% of patients with the mutation had relapsed compared to only 8% of patients with a normal KRAS gene.
The bottom line
The authors concluded that testing for KRAS mutations in patients with stage II or stage II colorectal cancer can help predict worse patient outcome.
The fine print
The short duration of this study means the impact these mutations on overall survival could not be investigated. Future research will be required.
Published By :
Annals of Surgical Oncology
Date :
Jun 03, 2014
