How Chemotherapy Works
Chemotherapy is a general term which encompasses the hundreds of drugs that target cancer cells. Cancer cells ignore the normal rate of cell division, and continue dividing rapidly in an uncontrollable manner. Chemotherapy drugs are designed to target these cells. However, chemotherapy also affects normal cells that divide quickly such as cells in hair follicles, the mouth, digestive tract, and bone marrow. This causes side effects such as hair loss, nausea, and lowered immunity.
In chemotherapy, a singular drug or a combination of drugs may be used, depending on the tumour type and its characteristics. The cancer’s stage, hormone-receptor status, lymph node status as well as the patient’s general health will affect the chemotherapy regimen the doctor recommends.
The types of cancer cells and the different combinations of drugs that affect them are constantly being studied in internationally recognised evidence-based clinical trials. Some drugs can interfere with the way cancer cells divide, and even damage the genetic structure of these cells.
Chemotherapy has two possible goals:
Cure: The aim here is to destroy the tumour, up to the point where even microscopic traces of the disease are eradicated. In this case, chemotherapy can be used as the main treatment. It can also be given after cancer surgery to decrease the risk of the tumour coming back after being removed. This is called adjuvant therapy.
Control: In cases where the tumour has advanced to stage 3, the tumour may be too large to be operated on without intensive surgery. To reduce the burden on the patient, chemotherapy shrinks the tumour to a size that can be operated on. This is called neoadjuvant therapy; therapy before surgery.
If the tumour has advanced to stage 4 and has become inoperable, the aim here is to weaken and shrink the tumour to the point where the symptoms of cancer are manageable. In stage 4, the tumour has become invasive and spread to other areas in the body, causing blockages, pain, and breathing difficulties to the patient. Here the aim of chemotherapy is to maintain quality of life for the patient as well as to maximise their quantity of life. This is called palliative chemotherapy or palliation.
Dr. Sangeetha Poovaneswaran is a resident consultant oncologist at KPJ Damansara Specialist Hospital, and is board certified to practise as a Consultant Clinical Oncologist and Radiotherapist in the United Kingdom as well as in Malaysia.
