Chemotherapy is a drug or combination of drugs that travels throughout the body to eliminate cancer cells. Chemotherapy can be used either before or after surgery during treatment for rectal cancer.
Memorial Sloan-Kettering’s colorectal disease management team includes medical oncologists who specialize in chemotherapy for colorectal cancer. Our physicians understand the subtleties of chemotherapy regimens and personalize your treatment, optimizing its strength while minimizing unnecessary side effects as much as possible.
Personalized Medicine for Rectal Cancer
During your diagnosis and staging, a pathologist will analyze your biopsy samples to look for specific genetic mutations in the tumor. Knowing which mutations are present in (or absent from) your tumor can help your medical oncologist to select drugs that may lead to a better result and prevent you from needing to cope with side effects of medications that are unlikely to work.
It is now known that some standard chemotherapy drugs are not effective in rectal tumors carrying certain mutations. For example, rectal cancer patients with certain mutations in the KRAS gene, which encodes a cell-signaling protein, do not respond to the chemotherapy drugs panitumumab and cetuximab. Consequently, patients with KRAS mutations are treated with other chemotherapies.
If genetic tests indicate that your tumor has specific mutations, you may be eligible to participate in a clinical trial of a new, experimental treatment approach. Speak with your physician to find out if a clinical trial might be an option for you.
Chemotherapy before Surgery: Neoadjuvant Therapy
If you have locally advanced rectal cancer, or if the tumor is lying low in the rectum, your doctor may recommend chemotherapy before you undergo surgery. Chemotherapy can help to shrink the tumor before the operation, making it easier to remove.
Neoadjuvant chemotherapy is often combined with radiation therapy before surgery. Using these two approaches together can enhance the effectiveness of each.
Chemotherapy after Surgery: Adjuvant Therapy
Following surgery for rectal cancer, many patients will be cancer-free. However, in some patients, microscopic tumor cells that were not detectable before or during surgery remain in the body and will eventually grow into new tumors.
As a result, your oncologist may prescribe chemotherapy to target the remaining tumor cells. Patients whose cancer has spread from the rectum to the lymph nodes, for example, now routinely receive chemotherapy.