CHEMOTHERAPY IN BREAST CANCER
What is chemotherapy?
Chemotherapy is administration of 'cytotoxic' drugs into the body, by either an intra venous line, or by some systems, which are implanted into the major veins of body. 'Cytotoxic' implies lethal to the cells. The cells of a cancer divide very rapidly, and are out of genetic control of a body (Genetic control maintains the turnover of the cells and does not allow them to exceed beyond a certain number). Chemotherapy agents are targeted at such rapidly dividing cells, and act by various mechanisms. However, there are many normal cells which also have a rapid turnover, and such cells are affected by chemotherapy resulting in the common side effects that we usually see.
What are the types of chemotherapy for breast cancer?
The types of chemotherapy for breast cancer vary according to the stage of the disease, whether prior surgery has been done or not, and our intent of giving CT. 'Intent' means that are we giving the chemotherapy to achieve a cure and reduce chances of disease coming back (intent is curative ), or are we giving it in a very advanced stage just to achieve some prolongation of life, but cannot achive a cure (intent is palliative ). So depending on the 'timing' of chemotherapy and the 'intent' of chemotherapy, the following nomenclature is used to describe the types of chemotherapy and the same is maintained through out this site.
Adjuvant: When chemotherapy is given after a curative surgery, with an aim to decrease the chances of the disease coming back, it is called as 'adjuvant' chemotherapy.
Neo adjuvant: When the primary disease is in a 'locally' advanced stage and not operable (due to its relations with surrounding structures, blood vessels, bulky lymph nodes etc.), but has not spread to any distant organ, chemotherapy can be given to achieve a decrease in the size or stage of tumour ('down sizing' or 'down staging'), so as to make it operable. Not all tumours may respond, however. If they respond, and decrease in size, surgery may be feasible. If they don't respond, or even increase in size, then it implies that the given chemotherapy is not effective, and some other chemotherapy needs to be tried, or we may have to call it a day.
Palliative: When the disease is metastatic (spread to distant organs), or is inoperable or has recurred and is not amenable for surgery, chemotherapy is given to arrest the growth of disease temporarily, or to slow down disease progress, so as to prolong survival of the patient. In these conditions, we cannot cure the disease; all we can do is increase the survival time of the patient.
In a similar fashion, chemotherapy is also labelled as 'First' line, 'Second' line etc. If a patient of breast cancer undergoes a curative treatment and receives CT during same, that will be first line CT. Then suppose she is fine for a couple of years, and then develops a recurrence for which she now receives one more round of CT. This would be second line chemotherapy, and so on. Presently, the treatment of breast cancer has upto four (or five) lines of chemotherapy as a standard of care.