Primary tumour location within the colon is an important prognostic factor for both early and advanced colorectal cancer. Over the past decade, researchers have found that mCRC patients who present with a Right-Sided Primary (RSP) tumour are more difficult to treat, because they are less responsive to standard-of-care chemotherapies and have fewer treatment options available, since the tumours do not respond to some biologic agents such as EGFR inhibitors (cetuximab and panitumumab).1
1. Clinical Practice Guidelines in Oncology (NCCN® Guidelines), Colon Cancer Version 2.2017 – March 13, 2017
https://www.nccn.org/professionals/physician_gls/pdf/colon.pdf