Adjuvant chemotherapy
The administration of adjuvant chemotherapy to breast cancer patients goes a long way in preventing the recurrence of the disease especially any distant recurrence. The recommendation for chemotherapy may be done where the breast cancer is invasive, has prognostic factors that are unfavourable, is a particular size or its spreading has reached the nearby lymph nodes. It can also be recommended if the patient is relatively young when the cancer was diagnosed since there is a high possibility of recurrence as they advance in age. Adjuvant chemotherapy refers to the approach of treating cancer that involves combination of different kinds of healing. It aims at destroying cancer cells that remain after treatment but which are usually undetectable. The purpose of this paper is to show the benefits of adjuvant chemotherapy treating breast cancer using more than one drug1.
The combination of more than one drugs is referred to as combination chemotherapy. The basis for any combination chemotherapy is the usage of drugs that function through diverse mechanisms so that to decrease the likelihood that there will be development of resistant cancer cells. When the combination of drugs with different effects is done, each of these drugs can be useful when given as optimal dose without severe side effects that are intolerable. After surgery is done to remove breast cancer that is in the early stage, many patients especially women are treated with a combination of various drugs2. The treatment given after the surgery usually aim at lowering the recurrence of the cancer coming back especially the postmenopausal women. Studies have showed that women who are in the postmenopausal age and are diagnosed with early-stage breast cancer that is hormone-receptor-positive and whose spreading has reached the lymph nodes have better chance of survival after the administration of adjuvant chemotherapy. In fact, after they were given the combination of adjuvant chemotherapy and adjuvant hormonal-therapy, the risk of recurrence was lower and they were more likely to live longer than women who were given hormonal therapy alone. Also, giving administering hormonal therapy after doing chemotherapy was better than administering chemotherapy and hormonal therapy at the same time2.
Thus to avert the recurrence of breast cancer after surgery, it is necessary to use adjuvant chemotherapy using more than one approach in order to attain the maximum benefit of it. For any cancer, the optimal approach is to combine surgery, chemotherapy and radiation therapy. Radiation or surgery therapy is useful in treatment of locally confined cancer , while adjuvant chemotherapy kills the cancer cells that have with time spread to locations that quite distant. Combination chemotherapy is the best attempt by medicine to avert the mutation of the cells or any resistance. Through the combination of various drugs or chemotherapeutic agents, there is usually an achievement of cells’ kill that is more complete. The cancer cells are destroyed by more than one drugs by use of collaboration by creating disruption at various phases of the cycle of cell reproduction cycle. The body cells pass through five stages in the reproduction cycle4. Most drugs for chemo work at a particular stage of the cycle only, while others are not specific for a certain stage. Attacking multiple stages of the cycle in cell replication is logical, so that to avert a mutation or resistance from happening or the recurring of the cancer after radiotherapy or surgery. The treatment of breast cancer using adjuvant chemo with different drugs can be compared to other treatments. A good example is the use of chemo therapy combination in the treatment of cancer of the lung. An accepted method of treatment for lung cancer cells that are small using etoposide and cisplatin together with external radiation. These two drugs form a good combination because they have distinct action mechanism but divergent toxicities. Cisplatin creates disruption during cell replication through cross-linking of the strands for the DNA. The drug is an effective killer of cancer cells, although it’s known for high renal toxicity3.
A great strategy is applied by oncologists in the development of various combination of chemotherapy drugs or agents. The first strategy is to ensure that drugs will be effective in the treatment of cancer type. Moreover, every drug attacks the cell malignancy using a mechanism of action that is different. For instance, a drug may cause the disruption of replication process for the DNA while another drug cause interference to the synthesis of proteins. By using more than one drug which have various action mechanisms, the possibility of evolution of a mutated cell-line is reduced. The combination of these drugs consider the toxicity. To achieve effectiveness in adjuvant chemotherapy, the combination of the drugs will aim at avoiding a second insult to the affected organ. Every drug’s effect on the liver, bone marrow or renal function should be put into consideration. The toxicity of the drug can result to additive effect. Combining the therapy aims at obtaining synergy in the killing while at the same time avoiding the additive toxicity2.
The triumph in empirical combination in chemotherapy was developed in the 1960s in the treatment of lymphoma and leukaemia and sometime later for tumour type in adult that were drug resistance which resulted in the promulgation of several principles of developing therapy regimens for multiple drugs4. The criteria applied was using a combination of drugs that are normally active when used as single agents with doses and schedule where the activity of single agent had already been approved. This resulted in the incorporation of drugs having different types of toxicity in a normal tissue. The cycle of the cell and drug action biochemical consequences were also regarded as necessary and therefore the combination of drugs with distinct action mechanisms and action site in the replication cycle were considered favourably. The attention later turned to the significance of drug resistance and the mechanism involved in the resistance, and the investigation of non-cross-resistant drug function combination was done. The results recommended selection of drugs that have similar methods of action but separate resistance mechanisms4.
Therefore, surgery aims at removing all the cancer that is visible, while adjuvant chemo is aimed at killing any breast cancer cells that may have remained but are invisible even after imaging tests are done. If the growth of these cells is allowed, new tumours would form in other body parts. Combination of various drugs in adjuvant chemo can lead to reduction of the risk of any recurrence. The use of a single drug is very unlikely to lead to reasonable cure, especially taking into account that there is a possibility of the cancer cell developing resistance.
References
Ponder,A. Waring ,M.(2012). The Science of Cancer Treatment.41-42
Breast Cancer org. (2009). Research Continues to Show Benefit of Chemotherapy after Breast Cancer Surgery. Retrieved from: http://www.breastcancer.org/research-news/20091212b
Motzer RJ1, Sheinfeld J, Mazumdar M, Bajorin DF, Bosl GJ, Herr H, Lyn P, Vlamis V.(1995).Etoposide and cisplatin adjuvant therapy for patients with pathologic stage II germ cell tumours.
DeVita, V., Chu E. (2008). A History of Cancer Chemotherapy. Retrieved from: http://cancerres.aacrjournals.org/content/68/21/8643.full
