Colorectal Cancer (Bowel Cancer) Treatments
Targeted therapies target specific molecules in the cancer cells. The aim of targeted treatments is to block specifically the growth and spread of cancer cells, while causing a limited damage to healthy cells. For colorectal cancer, they are often used either along with chemotherapy or alone, if chemotherapy is no longer working.
KRAS, NRAS and BRAF gene mutations
Scientists today understand a lot more about certain changes in genes (small functional units in your genetic material, also known as DNA) that drive the way a cancer behaves and grows. Scientists have identified several mutations (changes in genes) present in three genes that are involved in colorectal cancer: the KRAS, NRAS and BRAF genes.
KRAS mutations are the most common in colorectal cancers with a frequency of 30–50%; BRAF are 10–20% and NRAS are found in about 3–5% of colorectal cancers.
You may be tested to see if mutations in any of these three genes are present in your cancer. This will help your clinician to decide the best treatment approach. Your tumour cells will be examined with different techniques that can reveal mutations in specific genes. This will allow to obtain your molecular profile.
For the medical team it is important to identify your molecular profile, as this may affect your prognosis and the presence or absence of these mutations can help decide the best treatment, and whether specific drugs might be effective or not.
Treatments that target EGFR (anti-EGFR treatments)
Epidermal growth factor receptor (EGFR) is a molecule that helps cancer cells grow. Treatments that target EGFR are known as EGFR-inhibitors and can stop cancer cells growing. EGFR-inhibitors approved in Europe for use in colorectal cancer include the drugs cetuximab and panitumumab. These are generally used in the advanced stages of colorectal cancer.
EGFR-inhibitors generally do not work in colorectal cancers that have mutations in the KRAS, NRAS or BRAF genes.
Before you receive any anti-EGFR treatment, your tumour cells will be tested to establish your molecular profileince these treatments work only in people who do not have any KRAS, NRAS or BRAF mutations.
Treatments that target VEGF (anti-VEGF treatments)
Vascular endothelial growth factor (VEGF) is a molecule that helps tumours form new blood vessels to get nutrients they need to grow. Anti-VEGF treatments aim to starve the tumour of the nutrients it needs to grow and spread. Anti-VEGF treatments approved in Europe for use in colorectal cancer include bevacizumab, ramucirumab and ziv-aflibercept. These are generally used in the advanced stages of colorectal cancer.
Treatments that target BRAF
BRAF is a molecule that helps control cell growth. In some colorectal cancers, an abnormal (mutated) BRAF molecule helps cancer cells to grow. Some drugs, known as BRAF-inhibitors, target this abnormal BRAF and stop it from helping the growth of cancer cells. BRAF-inhibitors approved in Europe for use in colorectal cancer include encorafenib, which is used in combination with the EGFR-inhibitor cetuximab.