Cancer is a worldwide problem, affecting many people across the world in different parts of the body. Cancer has many symptoms that are common to “less serious diseases” and can be caused by a combination of many carcinogens [Cancer research uk].It is the process of uncontrollable cell division, resulting in an extra mass of tissue being produced, called a tumour [book]. There are many effective treatments used to try and combat cancer such as chemotherapy, radiation therapy, surgery and specific anticancer drugs [NCI]. Combining these methods can help reduce the toxicity and side effects, resulting in a less painful treatment [BOOK]. In this essay, I will look further into one of the most common treatments; chemotherapy and will discuss if concurrently taking antioxidants can enhance the efficacy of chemotherapy or not.
Depending on factors such as “how far the cancer has spread, age of patient and the general health of patient”, [ref] the type of treatment recommended, varies from patient to patient. Chemotherapy is used in x% of cancer patients and it involves cytotoxic drugs being administered into the blood stream [ref]. It is available in many different pharmaceutical formulations and works by producing free radicals which “damage the DNA inside the nucleus of dividing cells” [ref]. As our body develops, many normal cells stop dividing and form resting cells. However, cells in our hair, skin and nails for example, continue to grow and divide. As a result, chemotherapy is effective in most cancer situations but has many side effects such as loss of hair, low blood cell count, tiredness, nausea and diarrhoea, as the treatment also acts upon normal cells. However, many of these side effects are reversible as your body will adequately replace the normal cells, after chemotherapy has been stopped [cancer org research].
In spite of this, the unstable free radicals produced by chemotherapy, not only react with the cancerous cells but can also act on other proteins found in DNA or cell membranes, causing their structure to change and mutation to occur [ref]. Antioxidants can be given to reduce the dangerous effects of free radicals. They act by chemically binding to the free radical compound, stabilizing and stopping them from reacting with other compounds, thus why they are also known as “free radical scavengers” . They are found in many natural foods, such as fruits and vegetables but can also be given as a supplement via tablets and capsules [ref]. The use of antioxidants alongside chemotherapy has been argued, that the antioxidants are selectively protecting the normal cells from the toxicity effects of chemotherapy. On the other hand, it has been argued that the antioxidants are not selective and also protect the cancerous cells, preventing chemotherapy from working.
Lissoni et al has conducted a lot research into the use of the antioxidant; melatonin and the effects it has upon chemotherapy. Performance was measured in two different groups of patients with non-small cell lung cancer; one using chemotherapy alone and the other group using chemotherapy with melatonin. The results evaluated by the World Health Organisation, found that the tumour response rate was in fact higher in the group that received melatonin with chemotherapy. On top of this, it was found that myelosuppression, neuropathy, and cachexia were lower in the group with melatonin, meaning that the toxicity levels produced by the chemotherapy where reduced. Later studies and further research by Lissoni et al with more patients (250), showed similar findings but also found that the use of melatonin resulted in a higher complete response rate, compared to the group that used chemotherapy treatment alone. After a long follow up period, patients from the group using the melatonin administered with chemotherapy, also experienced an improved quality of life. Therefore, the study is positively in favour for the use of antioxidants, as they improve survival rates and help to reduce toxicity levels (help reduce side effects too).
More support in favour for the use of antioxidants with chemotherapy, comes from the analysis of “Impact of Antioxidant Supplementation on Chemotherapeutic Efficacy: A Systematic Review of the Evidence from Randomized Controlled Trials,” [your notes]. Conclusions, drawn from this report of 845 studies with patients of many different cancer types, showed that antioxidants such as vitamin A, C, and Beta Carotene, positively help treatment responses. The trial goes against any of the views that suggest antioxidants disadvantage the use or efficiency of chemotherapy. In fact, the data produced better results for the antioxidant group compared to that of the control group. Also, the antioxidant group experienced similar or lower rates of the known side effects of chemotherapy, such as diarrhoea, than the controlled group. Sergio et al [date] carried out research on the use of B-Carotene and other Carotenoids with chemotherapy. They too, found positive effects on health and increased activity against free radicals. Further support has come from conclusions of the work led by Drisko et al. They found that when using common antioxidants; Vitamin A, C, E and Beta-Carotene, alongside cancer treatment, helpful benefits were obtained as the antioxidants acted as electron acceptors, tackling the free radicals. Thus, the conclusions from the studies so far, suggest strong support for the use of antioxidants, as treatment responses proved more successful combined with antioxidants.
However there is much evidence against the use of antioxidants, as it is argued that antioxidants affect the efficacy of chemotherapy. Bairati et al (DATE) conducted an experiment which was based on 540 cancer patients; some of which were taking antioxidants whilst undergoing chemotherapy and others which were treated with a placebo. The findings showed that the patients, who were taking the antioxidants, had reduced side effects caused by the chemotherapy. He also stated that those patients, who smoked compared to those who didn't, had reduced chemotherapy side effect improvements. On the other hand, the patients' mortality had decreased, due to the severe interaction between the antioxidants and the chemotherapy. This may be due to the fact that instead of chemotherapy destroying the cancerous cells, the use of the antioxidants was protecting the cells and therefore, stopping the cells from dying.
Research against the use of antioxidants with chemotherapy, also comes from a study carried out by Lesperance et al [date], which showed how 90 patients with early stage breast cancer using antioxidants, produced a worse survival rate than 180 matched controls, although, other confounding variables were not clearly measured and taken into consideration. However, it does raise a concern to the use of antioxidants and questions any further application of antioxidants in concurring treatment for cancer. Further to this, a study by Pathak et al found similar results, which showed that there were no significant differences in the tumour response rates, overall survival and toxicity rates. The study involved testing 136 patients with non-small cell lung cancer, some of whom received chemotherapy alone, whilst others received chemotherapy alongside multiple high dose antioxidants (Vitamins C, E and Beta Carotene). The use of the combination after 2years, showed 15.5% survival rates, with chemotherapy alone being 11.1%. Although there was a slight increase, the difference is not sufficient enough to come to a clear conclusion whether or not this combination works. It could be argued that using a larger sample of trials, the difference produced could be great enough to support the use of antioxidants with chemotherapy. However, stating the research carried out by Lawenda et al [your notes], results showed antioxidants did help reduce the effects of chemotherapy and the toxicity produced, but still they concluded that the use of high dose antioxidants should be avoided [ref]. It is clear that physicians feel that antioxidants do not protect the patients, but instead, interferes with the killing process of cancerous cells.
Overall, there have been many studies suggesting whether or not antioxidants enhance chemotherapy or not. Although there are some studies for the use of antioxidants, there are many studies suggesting that antioxidants interfere with the chemotherapy, resulting in a loss of control over the cancer growth. However, many of the studies have been small trials involving patients with different cancers at different stages, conducted under different conditions, using a wide range of antioxidants at different doses and combinations. This has lead to a wide range of opinions with insufficient data, needed to make a clear conclusion. Nevertheless, as some trials have suggested that there may be some interference with the chemotherapy treatment, I would encourage against the use of antioxidants. However, the flaws in experiment procedure and the understanding if antioxidants are selective to normal cells or not, need to be experimented further, before advising patients whether or not antioxidants will enhance chemotherapy.
http://www.cancer.gov/cancertopics/what-is-cancer - what cancer is
http://caonline.amcancersoc.org/cgi/content/full/55/5/319 There are considerable in vitro and animal data showing that vitamin C and other antioxidants can protect cells against radiation and chemotherapy. This goes against the use of antioxidants.
THIS GOES AGAINST THE3 USE OF ANTIOXIDANTS http://www.sciencedaily.com/releases/2009/06/090608071943.htm
http://www.ezhealthydiet.com/free-radical-damage.html free radicals-di9et