Chemotherapy (chemo) uses drugs to treat colon or rectal cancer. Drugs and biologic agents used in chemo may kill cancer cells directly or keep them from dividing and spreading the tumor.
Chemotherapy for colorectal cancer has expanded greatly in the past ten years. From a single available drug, there are now five chemotherapy drugs and three biologic agents approved by the FDA to treat the disease.
In the past few years, new targeted biologic agents have come into use that are aimed at blocking signals in cancer cells that lead to their growth. The goal of current biologic therapy for colorectal cancer is to prevent blood vessel development, block cell division, or trigger cell death.
Chemotherapy drugs commonly used to treat colorectal cancer
- Fluorouracil — commonly called 5-FU
- Leucovorin — also called folinic acid — which is only used in combination with 5-FU
- Capecitabine — Xeloda® — an oral prodrug of 5-FU which is converted to 5-FU in the tumor
- Oxaliplatin — marketed as Eloxatin®
- Irinotecan — available as a generic drug and as brand name Camptosar®
- Avastin® (bevacizumab)
- Erbitux® (cetuximab)
- Vectibix™ (panitumumab)
Most drug treatments or regimens now use a combination of several drugs, and in advanced colorectal cancer, may include both chemotherapy and biologics.
Treatments are becoming more personalized. Genetic researchers are finding biomarkers — abnormalities in genes that predict effectiveness and safety for a drug in a particular person. Testing of proteins will, in the future, help identify more specifically what is causing a cancer cell’s uncontrolled growth — and what drugs could be targeted to turn off the gene producing the protein.
Unfortunately, it is difficult to target only cancer cells with chemotherapy. Since cancer cells are dividing and growing rapidly, chemotherapy often aims at such fast growing cells. But cancer cells are not the only cells that divide and grow quickly. Cells in the mouth, gastrointestial tract, hair, skin and bone marrow cells also divide often, and chemotherapy can effect them, leading to side effects such as mouth sores, nausea, diarrhea, loss of hair, tender skin and low blood counts.
Balancing destroying or controlling cancer with side effects that don’t harm patients is difficult. If you have chemotherapy treatment your health team may choose and change drugs, dosages, and timing for the most effectiveness with the best safety for you.
One size does not fit all!
Chemotherapy may be given as
- Neoadjuvant therapy: before surgery to help shrink the tumor and make surgical removal easier. This is commonly used for rectal cancer or cancer that has spread to the liver.
- Adjuvant therapy: after surgery to prevent cancer from coming back or recurring.
- Palliative therapy: to lengthen and improve quality of your life, slow the spread of cancer; or to relieve pain in cancer that has spread. In palliative therapy the goal is not to cure the cancer but to manage its symptoms.
- Chemoradiation: Chemotherapy drugs given simultaneously with radiation treatments to make radiation more effective, for instance, before or after surgical removal of rectal cancer.
Where Can You Find More Information
The National Cancer Institute has a patient booklet Chemotherapy and You: Support for People with Cancer that answers many questions about chemotherapy treatment. It is available to read online or you can order it free from NCI.
Scott Hamilton, cancer survivor and ice-skating champion, has developed ChemoCare.Com, a website with patient-friendly information about chemotherapy in collaboration with the Cleveland Clinic. Information is both accurate and very practical, helping with the journey through chemotherapy and beyond it.