The use of targeted therapy for colorectal cancers—which are cancers of the large intestine, including colon cancer and rectal cancer—has increased significantly over the past five to 10 years.
“We’ve seen significant improvements in outcomes in patients who receive targeted therapy for metastatic disease,” says Elliot Newman, MD, chief of surgical oncology at Lenox Hill Hospital, Northwell Health System. “We know that in those patients, adding different types of targeted therapies can improve survival significantly—compared to patients who are not receiving targeted therapies and just receiving chemotherapy alone.”
How Targeted Therapy Treats Colon Cancer
Colorectal cancers develop because of abnormal gene and protein changes in cells. “Some of these abnormalities can be targeted,” says Dr. Newman.
Targeted therapies work differently than traditional chemotherapy. “Chemotherapy generally is given because it works on cells that divide rapidly, like cancer cells. But chemotherapy will also affect other cells that divide rapidly in the body and they may be normal cells,” says Dr. Newman. “Targeted therapy is aimed more specifically at changes that relate just to the cancer cells.”
These abnormal changes in cells are specific proteins that help cancer cells grow and/or survive. “By blocking the receptors that help tumor cells grow, or sometimes help blood vessels grow, we have the ability to shut off this stimulant to grow and multiply the cancer cells,” says Dr. Newman.
Some of the targeted therapies that are used to treat colorectal cancers include:
Drugs that target vascular endothelial growth factor (VEGF): VEGF is a protein that helps tumors form new blood vessels (a process known as angiogenesis). This allows them to get nutrients so that they can grow. These drugs inhibit VEGF which can slow or stop cancer growth in come colon or rectal cancers.
Drugs that target epidermal growth factor receptor (EGFR): EGFR is also a protein that helps cancer cells grow. Drugs that target EGFR can be used to treat some advanced colon or rectal cancers.
A doctor may also offer a different type of targeted therapy called a kinase inhibitor. Kinases are proteins that carry important signals to the cell’s control center. These drugs block several kinase proteins which help stop the growth of cancer cells.
“There are very specific situations where the targeted therapies work—they don’t work all the time,” says Dr. Newman. “It’s important for patients to discuss that with their doctors as to whether or not they're a good candidate for targeted therapies, and what the best type of therapy would be, based on their specific situation."