A later introduction of anti-EGFR drug is as effective as the standard therapy for advanced colorectal cancer

This study compared the effectiveness of chemotherapy combined with bevacizumab (Avastin) or anti-EGFR drugs for treating advanced colorectal cancer (CRC). Researchers suggested that anti-EGFR later introduced in the treatment of these patients did not impact the outcomes of patients. 

CRC is the third most common cancer worldwide. A significant number of patients present advanced disease at diagnosis. The standard treatment used to be chemotherapy and radiation therapy. In advanced cases, this treatment is only of limited effectiveness. Therefore, the addition of other agents such as bevacizumab is another option. Bevacizumab is a targeted therapy that stops the growth of new blood vessels in the tumor. This stops tumor growth. 

More than half of patients with advanced CRC have a RAS mutation (permanent change). This mutation is associated with more aggressive tumors. These patients can benefit from the addition of anti-EGFR agents such as cetuximab (Erbitux) or panitumumab (Vectibix). These agents bind to the epidermal growth factor receptor (EGFR; a protein necessary for tumor growth) and block the growth of the tumor. Prior studies showed that the effectiveness of cetuximab is limited in patients that are RAS positive. Therefore, suggesting that these patients should be tested for RAS before starting the treatment. However, RAS testing might take up to 20 days. 

It is not clear if these patients should start treatment immediately with bevacizumab or wait for RAS status and then receive anti-EGFR agents (if RAS negative). 

This study included information about 262 patients with metastatic (spread to other parts of the body) CRC. These patients were assigned to different groups. Group 1 (129) was treated immediately with chemotherapy and bevacizumab. Group 2 (133) included patients who received chemotherapy first followed by delayed cetuximab treatment. Overall survival (OS; time from treatment to death by any cause), progression-free survival (PFS; time from treatment to disease progression) and tumor response were measured. 

The average time to receive RAS status was 19 days. The average OS was similar for both treatments. Group 2 had a 26% improvement in the odds of a better PFS. Tumor response to the treatment was significantly higher in group 2 (66.7%) when compared to group 1 (45.6%).

This study concluded that while waiting for RAS status patients should start chemotherapy and then receive anti-EGFR agents if RAS negative. 

This study was based on information from medical records. Therefore, some data might be missing. More studies are needed.