Dr. Grothey on Left- Versus Right-Sided Tumors in CRC

Axel Grothey, MD, a medical oncologist and director of Gastrointestinal Cancer Research at West Cancer Center and Research Institute, discusses left- versus right-sided tumors in colorectal cancer (CRC). 

In CRC, the location of the primary tumor plays a major role in tumor biology and treatment selection, says Grothey; however, the definition ​of sidedness is still unclear. 

Moreover, ​although Europe and the United States have different viewpoints regarding sidedness, it ​is widely understood that CRC, whether sigmoid or descending, is left-sided. 

​Studies have shown that right-sided tumors tend to be more aggressive, and patients have a shorter overall survival upon metastasis, explains Grothey.

Additionally, these studies demonstrated that right-sided tumors do not benefit from EGFR inhibitors, such as cetuximab ​(Erbitux) or panitumumab (Vectibix) in the first-line setting. ​Conversely, bevacizumab (Avastin) has shown benefit in right-sided tumors, Grothey concludes.