Simply put, chemotherapy is used to kill tumor cells, slow tumor growth and prevent the tumor from spreading. Sometimes, chemotherapy is administered prior to surgery to shrink the tumor (called neoadjuvant therapy). In cases with extremely poor prognosis, chemotherapy may be used to relieve symptoms (called palliative care).
Chemotherapy may be administered by two different means:
- Systemic Chemotherapy. In this therapy, the drug is delivered either by mouth as a pill or by injection into a vein. The drug enters the bloodstream and circulates systemically (throughout the body). This administration of chemotherapy has the advantage of destroying the cancer cells wherever they may be. Thus, tumor cells that have metastasized or spread to other parts of the body will be exposed to the drug as well.
- Intraoperative Chemotherapy. In this therapy, the drug is delivered locally to the site of the cancer usually through a small tube straight into the body cavity where the tumor is located. Chemotherapy drugs given this way are concentrated where the tumor is located; however the drug is still absorbed into the bloodstream. This approach allows doctors to deliver a higher dose to the tumor while simultaneously limiting the side effects often experienced in systemic therapy. When delivered by this method, chemotherapy drugs are sometimes heated first which may help them work more effectively.
Chemotherapy drugs may be given as single agents, but often, two or more drugs are given simultaneously, because this has been found to increase treatment efficacy.