Cancer is the uncontrolled division of abnormal cells, these cells are abnormal because of mutations in their DNA sequences, base pairs could be subtitled, deleted, replicated and reversed, the errors result in the coding for different amino acids which ultimately means a different protein being synthesised, in cancer cells the protein that acts as a 'on and off 'switch for a hormone signal that tells the cells to replicate is either damaged or missing. This means cancer cells don't 'know when to stop replicating and surpass the hay flick number (the max number of times a cell can divide) which is around 50/60. Cells divide by mitosis; this process is has four stages interphase, prophase, metaphase, anaphase and telophase. The actual replication of the mutated sequence occurs in the interphase were the cells gets ready to divide.
Figure 1Cancer cells also have another property which make them abnormal, they don't specialise. In fact the cancer cells become less mature over time making them divide even quicker and that's the reason why the chances of survival are higher in the earlier stages of the cancer. Figure 3 shows a negative correction between the survival rate and the months the cancer cells have been active in the body http://imaging.ubmmedica.com/cancernetwork/journals/oncology/images/unwinding/200311supp2-19-1.gif
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Cancer cells lastly have another property which is that they have fewer molecules on the surface of the cell; this makes the hard to stay in one place, figure 1 shows cancer cells breaking the basement membrane detaching form the tumour due to the reduced number of molecules on the surface of the cell.
Figure 1Cancer cells form lumps or tumours which stop and reduce the function of other cells by pressing the normal local cells around it and forcing itself through normal tissue, in figure 2 you can see the cancer cells forcing its way through the middle layer of cells this creates the pressure.
Figure 2Diagram showing a tumour forcing its way through normal tissue
Figure 1The problem
As cancer grows it damages and ruptures small blood vessels, the affected area is starved of oxygenated blood, and the cells can't respire and start to die. Cells make up tissues; different types of tissues make up organs which lastly are placed in systems like the respiratory system. If large areas of cells are effected organ failure can occur and this is fatal. Different stages of cancer further complicate the problem, there are 4 stages of cancer, first stage is when the cancer is relatively small and can be treated easily and the fourth stage or the metastatic stage where the cancer has spread too many different parts of the body and the cells are very immature, survival is little to none.
What is lung cancer?
Cancer which first started replicating in cells of the organs found in the respiratory system. Nose, mouth, trachea, the right and left bronchus and the lungs are all organs part of the respiratory system. There are two types of lung cancer, non small cell lung which is cancer that has spread to other parts of the body and for small cell lung cancer which hasn't spread.
The link between smoking and lung cancer
Figure 4 http://scottthong.files.wordpress.com/2007/01/smokinglungcancercorrelation.png
There is a direct causal link between cigarette consumption and lung cancer, smoking causes 9 out of 10 cases of lung cancer (1). The graph shows both cigarettes smoked and lung cancer deaths increasing and decreasing at around the same time intervals, considering the time lag for the data analysis.
Chemotherapy- the main method
Chemotherapy means using anti cancer (cytotoxic) drugs to 'destroy' cancer cells (5). Cytotoxic drugs not only 'destroy' cancer cells but any fast growing and replicating cell like the cells in hair follicles, hair loss is common in patients. There are many different types of chemotherapy drugs more than 90 in fact, all chemotherapy drugs ultimately target the cell during division and either stops it from occurring in the first place or interrupting a critical part so the procedure fails and the nucleus orders the cell to destroy itself.
The cell division stage is the 'M' stage, it is relatively short compared to the other stages, and the 'M' stage is when the chemotherapy attack, they circulate the blood until they find a cell at this stage(6).
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Different types of chemo drugs have different chemicals that go about doing this. One type of chemotherapy drug has alkylating antineoplastic agents that blinds an alkyl group to DNA, changing the structure slightly, the group is attached to the guanine base pair on the number 7 nitrogen atom of the purine ring(7). This minor change in molecular structure disrupts cell division by preventing the chromosomes from uncoiling, if chromosomes don't uncoil they can't be replicated and synthesised for cell division (phase 'S' is this stage).
Another type of chemotherapy is antimetabolics which pretend to be purine chemicals like mercaptopurine, these chemicals become the building blocks of DNA (6). Development and division of the cell cannot occur because the actual purine substances aren't incorporated in the s phase of the cell cycle (6) (figure 5).
Is chemotherapy a solution to lung cancer?
To answer this question I have found two trials.
Small cell lung cancer-A trial conducted by Dr Robin Rudd and supported by the London lung cancer group, recruited 241 people with small cell lung cancer they were give different combinations of the different types of chemotherapy drugs. The average length of time that people lived without any signs of the cancer growing was 5.9 months for one combination and 6.3 months for another combination of chemotherapy and one third of the of people lived for more than a year (33%)(8).
Non small cell lung cancer- A trial conducted again by Dr Robin Rudd and again supported by the London cancer group, recruited 422 which had four cycles of chemotherapy, research found four out of 10 people lived more than one year (30%)(9).
Chemotherapy increases the chances of suffers from lung cancer living longer, it is not a 'cure' because a person having chemotherapy might not experience a prolonged life and in fact die sooner than predicted. Only 30% (or so) of suffers surviving more than a year in is not great number , but comparing it to 5% the percentage of people without treatment surviving non small cell lung cancer, it's a massive difference.
Are the trials valid/ reliable?
To sign up to a clinical trial, the person wanting to sign up has to meet the requirements. The requirements are the cancer must be in a particular stage e.g. advanced lung cancer where the cancer has spread and be a particular age the London lung cancer group doesn't reveal the ages of the people so I can't access the info. Exposure to other risk factors, in the trial report it does not say that the people in the trial are smoking or not, smoking is a factor that makes the trials less valid. People smoking will increase the chance of the tumour growing and affect the overall percentage of people that live more than a year. The design of the trial also plays a big part in the accuracy of the results e.g. a poorly designed trial might just take size readings of the tumour every year. There are only 2 trials involving small cell lung cancer on the cancer research system, trials are not repeated with the same aim and could mean that the trials are not reliable. The sample size could affect the amount of symmetric error which can occur, but sample sizes are small.
Why chemotherapy is an appropriate method?
Chemotherapy might have allot of side but it is still the main treatment for cancer, this is because it actually kills/destroys the cells that are replicating and stops the growth of the tumour, unlike surgery and radiotherapy where particular parts on the spread cancer are concentrated on. There is a very high chance of the tumour returning after surgery/ radiotherapy this is because these too methods only destroy the cell but doesn't stop it from replicating.
Implications of chemotherapy
Economical- The cost of treatment for the patient itself is free* on the NHS, but the cost on the NHS is massive. It's averaged that a patient with lung cancer to be treated it costs about £35,000(10) pounds per cycle. Most of the money goes to actually buying the drugs and the rest to patient doctor consulting, this means that the time the doctor spends consulting the patient has a cost and lastly the cost of labour, nurses have to monitor the patient when the drugs are being injected.
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Ethical- Will the chemotherapy do more good do than harm, chemotherapy has many side effects for a drug that is commonly given to cancer patients. Side effects include hair loss, breathing difficulties, chest pain and vomiting. Quality of life is poor for people that are basically living their last days, is it right for these people to have such low Quality of life and a prolonged life just makes them suffer even more.
The economical implication has many disadvantages, the cost of the NHS in 2009 was 98.7 billion (10). This money is obtained through taxation. If the economic implication of chemotherapy wasn't go great less money would be spent on the NHS and so more money could be spent on other parts of the budget like education. A risk that can occur is that the budget for the NHS runs out and so trials like the one from London lung cancer group might not receive funding and so important information that might be vital in curing cancer might not be found.
The ethical implications also have many disadvantages for the patient and family, the family looking after the person that's having chemotherapy might not be able to care for the person properly because of all the side effects e.g. in a scenario where there's a four person family, the mother, father and two children, if the father has chemotherapy the family would need to care for him because he would be too fatigued to do anything for himself. This would be really hard considering the children need to go to school and the mother has to work to provide an income for the family.
Alternative method- radiotherapy
Is the use of electromagnetic radiation to destroy the cancer cells, radiotherapy doesn't target the cancer cells, it targets a particular area and normal cells are also destroyed. The way it works is by damaging the DNA of the cells, photons (packet of energy) are absorbed by the Atoms or molecules ionising them, the radiation ionises bonds in the cells water molecules releasing hydroxyl free radicals (unpaired electrons of the oxygen), the free radicals attack the DNA molecule causing damage and mutations that can break the polynucleotide strands. There are two types of radiotherapy external and internal. External is when beam of Electromagnetic radiation are fired using a machine or internal where a substance is eaten, drank or injected into the body emits radiation most likely in the form of gamma rays from an radioactive source.
Alternative method -Surgery
Surgery is only an option when the cancer is localised, it hasn't spread to different parts of the body yet. This is only because it treats the part of the body operated on. A surgeon or group of surgeons would remove the tumour and some unaffected tissue from around the cancer; this is referred to as a clear margin (11). The surgeon or group of surgeons can perform a biopsy to diagnose the type of tumour it is, so if it's a malignant tumour or a benign tumour and depending on that see how quickly the tumour would spend or if it's fatal. Lastly might be used to reduce the risk of cancer for example a woman might choose to remove her breast, if she is at a high risk of developing breast cancer (11).