Colon cancer is one of the most common cancers in Thailand. We do not currently know the exact cause of the disease; getting older or having a family history of colon cancer are regarded as major risk factors for the cancer. Any methods of current colon cancer screening make it possible to detect early stages colon cancer expeditiously, especially if found in the early stages, the chances of being cured are greater.
In general, surgical treatment is still the main treatment modality for colon cancer, particularly in patients with stage 1-3 cancer where there is no distant spread of cancer. But in the case of stage 4 patients that the cancer has spread to other organs, such as the liver and lungs, systemic treatment is the main stay of treatment. In most cases, both the surgeon and the internist who specialize in cancer treatment a--medical oncologist--will formulate a treatment strategy together.
Systemic treatment modalities for colon cancer can be classified into chemotherapy, targeted therapy and immunotherapy. Not all colon cancer patients will receive the same exact treatment. At present, test for mutated genes from a cancer biopsy specimen or from the blood of the patient are conducted to assist in making decisions and selecting the most appropriate drugs for each patient.
The goal is that the treatment must be effective with few side effects including not affecting the quality of life of the patient. The aforementioned groups of drugs can be administered together to enhance efficiency and reduce side effects from any one drug.
Systemic Treatment
- Chemotherapy drugs exert their effects on rapidly dividing and multiplying cells. In general, cancer cells multiply and grow at higher rate; hence, they are more susceptible to the action of chemotherapy drugs. However, normal cells in tissue such as the lining of digestive tract, hair and nail, also multiply at high rate, so they can be affected by chemotherapy as well. There are many forms of chemotherapy drugs including oral and intravenous forms. The type of chemotherapy selected for a patient depends on factors such as patients’ condition, medical history and stage of cancer.
- Targeted therapy drugs act more specifically on cancer cells and tend to spare normal cells from damage. However, targeted therapy is not suitable for everyone. Sometimes, certain test must be performed before starting the medication, for example, detection of RAS mutation genes before initiating anti-EGFR antibody drugs. The advantages of this group of drugs are their high efficiency and few side effects. Targeted therapy can be in the form of oral pills or intravenous injection. The type of targeted therapy employed will be at the discretion of the physician. Nowadays, doctors may prescribe targeted drugs in combination with chemotherapy to enhance the treatment outcome.
- Immunotherapy is a cancer treatment that strengthens the body's immune system, such as white blood cells, to be more capable and effective to fight foreign invaders in the body including cancer cells. It is worth noting that immunotherapy does not directly kill cancer cells. In general, human white blood cells can detect and destroy cancer cells. But sometimes there is dysfunction of the immune cells, allowing cancer to grow. Immunotherapy enhances the functional performance of white blood cells such as T-cell lymphocyte and NK cell to fight and kill cancer cells. Immunotherapy has fewer side effects, and most patients can tolerate it well.
There are many different types of drugs currently used to treat colon cancer. Each has its own mechanism of action and different side effects. There is no one best drug or drug class. However, we can now choose the most suitable drugs which are those that are effective in destroying cancer cells, have few side effects and do not affect patient quality of life.
