Biology Essay
a. Describe and evaluate the evidence suggesting a link between lifestyle and some forms of cancer. (18 marks)
Lung, Skin and Liver cancer are three of the most prevalent cancers in today’s modern society. All can be the result of our lifestyle choices; smoking, sun exposure and drinking alcohol excessively can be attributed to each of the cancer’s respectively. In this essay, I will be analysing the evidence which suggests these links.
Cancer is a very serious disease, accounting for 13% of all human deaths in 2007 (7.6 million). It is the result of abnormalities in genetic material, which is often caused by carcinogens in tobacco smoke, radiation and infectious materials such as asbestos. Other types of cancer can be caused by odd genetic abnormalities, and cancer can be passed genetically (although more work needs to be done in this field). Often, the first sign of a cancer will be a small growth, known as a tumour. Quick detection of a tumour allows it to be removed, and chemotherapy can be applied to kill the cancer. Quick detection means treatment can begin before the cancer metastasizes, so it doesn’t spread to nearby tissues; this would cause more damage to the body.
Cases of Skin Cancer are quickly increasing in the UK, with over 9,500 new cases reported each year, with 2,300 fatalities from the cancer. It is the most common cancer in the UK in the 20-39 age group. However, unlike Lung Cancer, it has a much lower mortality rate. This is due to quick diagnosis due to very visible skin growths. It is estimated that 85% of skin cancer cases in the UK are due to over exposure to sun.
There are three types of Skin Cancer: basal cell carcinoma, squamous cell carcinoma and malignant melanoma. BCC is the most common, present mostly on sun exposed areas of the skin, and especially on the face. They rarely metastasize, meaning that they rarely cause death (the cancer doesn’t spread). SCC is also very common, and again in unlikely to metastasize. Melanoma is the least common form of the cancer. However, melanomas often metastasize, and are deadly once this process begins.
BCC and SCC skin cancers often carry a ‘UV-signature’ indicating that these cancers are caused by UV-B radiation causing direct DNA damage. However malignant melanomas are predominantly caused by UV-A radiation, causing indirect DNA damage.

This graph shows the age-standardized number of deaths from Skin Cancer per 100,000 inhabitants across the world. It is clear that rates of Skin Cancer in the US and Australia, as well as in Southern African continent are some of the highest in the world; Australia has around 5.6-6.3 deaths per 100,000, compared to the UKs 2.1+. Possible reasons for this may be an increase in sun exposure in Australia. The country enjoys around 300 days of sun per year, with much a higher range of temperatures than the UK; 26-9˚C in Sydney compared to 23-5˚C in London. Australia also has a higher percentage of Caucasian residents than other warm countries in the world. As the graph below shows, Skin Cancer is much more prevalent in Caucasians than in Black or Asian races. This is reflected by the number of Chinese deaths due to skin Cancer- less than 0.7 (See World Graph above).

Table 4.1 also reflects a difference in the levels of skin cancer amongst men and women. There is a difference of 7.8 per 100,000 between women (14.0) and men (21.8). Looking at Skin cancer rates in South Africa, we see a surprisingly high number: 4.2-4.9 per 100,000. This figure is higher than other nearby countries. This is perhaps due to a greater number of White people living in the country, 9.2%, compared to surrounding African countries.
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Graph shows Skin Cancer diagnosis per year, for gender and race.
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Table Showing Average Temps in the UK and Aus. (˚C)
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We also know that skin cancer is rising: in the UK, between 1973 and 1998, Skin Cancer amongst white men rose from below 7.5 per 100,000 to below 20 per 100,000. A smaller increase was also noted amongst white women. At the same time however, cases amongst black men and women stayed relatively the same, below 2.5. (Dark skin means better resistance to UV rays). This increase could correlate to an increase in international travel and holidaying (to sunnier climates), and also an increase in the use of sunbeds.
Graph 4.2 shows that around 45% of men in 1999 used a sunbed over a 6 months period, and 55% of women. This was of men and women in the 16-24 age range; the age group where Skin Cancer is most prevalent. This could suggest a link between sunbed use and skin cancer.
Lung Cancer is another common lifestyle cancer, generally caused by smoking. It is the most common cause of cancer-related death, with over 1.3 million people dying from the disease globally each year. Primary Lung Cancer comes in two forms: Small-Cell and Non Small-Cell. Small-Cell is less common, but is more attacking to the body. It is immediately metastatic, meaning the cancer infiltrates nearby tissues, causing the cancer to spread, and generally carries a worse prognosis.
Smoking is the most common cause of Lung Cancer; smoking damages the alveoli; the small sacs at the ends of bronchioles. These fill up with Oxygen when the lungs inspire, and allow the oxygen to diffuse across the alveoli’s and into the bloodstream, to be transported around the body. They also allow CO₂ to leave the bloodstream. Smoking causes the alveoli tissue to become scarred, as carcinogens from the smoke enter the alveoli. This causes the tissue to become thicker, making diffusion much less efficient. As Fick’s Law states, Rate of Diffusion is proportional to Surface Area x Conc. Gradient/Diffusion Pathway. A shorter diffusion pathway will allow for faster and more efficient diffusion. Due to this, the heart has to work harder to process oxygen, leaving to fatigue and loss of breath. Because of this long term damage, the lungs become susceptible to cancer.
The Ciliated Epithelial cells lining the throat also become damaged by the carcinogens in the smoke. Normally, these cells clean the lining of the throat of particles trapped in mucus. However, smoking stops the mucus from functioning normally, meaning that they no longer can be cleaned from the throat. Again, the damage over a long time period can make the lungs more susceptible to cancer.


These graphs show the correlation between the number of Cigarettes smoked per person per year, and the number of Lung Cancer deaths per year, for both men and women.
Looking at the graph for males, we can see that as the number of cigarettes smoked per day increases, so do the number of deaths. There is however a lag between the numbers of cigarettes smoked per day increasing, and the number of deaths. This is due to the fact that lung cancer takes a long period of time to begin.
An interesting difference between genders appears on the graphs. The number of cigarettes smoked per year for males is much higher between 1910 and 1930, than for females, where it is close to zero. This can be explained by the context of society at the time; at the beginning of the 20th Century, smoking in public by women was not permitted. This began to change during 1930-40, as indicated by the graph. This corresponds to woman’s rights of the time; most women got the vote in 1928.
Both graphs show a fall in the number of cigarettes smoked per year, at around 1975. This may be due to more awareness of the hazards of smoking and the lung cancer it can cause, plus the introduction of warning labels on cigarette packs in 1971. The number of deaths however has not yet begun to fall; again this is because it takes a long time for lung cancer to develop, and obviously, a long time for the benefits of reduced smoking to be felt.
Liver Cancer is another lifestyle cancer caused by excessive alcohol intake, although it can also be caused by chronic hepatitis. Alcoholism leads to cirrhosis of the liver, where liver tissue is replaced by scarred tissue, fibrosis and lumps from the liver’s regeneration process. The effect of this is a progressive loss of liver function. Generally, liver disease, and liver cancer are only caused by long term, heavy drinking, over a period of a decade.
Graph 1.2 shows a distinct rise in the incidence rates of liver cancer, by sex, over a period of 31 years. Incidences are highest amongst men, going from around 2.0 per 100,000 in 1975, to 5.5 in 2006. This is an increase of 275%. Liver Cancer amongst Women has also increased, from below 1.0 to 2.5 in the same time period.
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Graph Showing Consumption against Mortality in the UK
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We also know that consumption of Alcohol has increased. This graph shows that Sales of Alcohol in the UK (According to HM Revenue and Customs Data), has increased from 1.25 per capita in 1984, to a peak of 1.75 in 2004. This graph also shows a correlation with mortality rates. Interestingly, since 2004 there has been a fall in both Consumption and Mortality. This may be due to increased education targeting Alcohol Consumption, and perhaps Drink Driving campaigns.
Graph 1.4 also shows us Liver Cancer incidence rates across the world in 2002. As we can see, Western Europe has around 7 cases per 100,000 male population, compared to a world average of 16 per 100,000 males. Rates seem particularly high in Eastern Asia and Africa. This may be due to higher rates of Hepatitis because of bad living conditions.
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Graph shows US recommended consumption against the UK, France and the Netherlands.
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North America has fewer incidences of Liver Cancer than Western Europe; 5 per 100,000 males. I believe this may be due to lower moderate drinking guidelines. This graph shows that US standardized drinking guidelines for Women are just below half the UK’s, and just above a quarter of France’s. For men, the difference between the US and UK is smaller, however all three European countries are greater. This suggests that consumption in the US is less, and as a result, incidences of liver cancer are fewer.
Overall, the evidence collected suggests a link between lifestyle factors and cancer. The data used is mainly collected from government sources, colated by cancer charities. It is importan to remember however that some data may be biased; charities use statistics to enchourage support, and this may lead to biased reporting. Also, figures on a global basis are not always entirely accurate. Some countries have inferior healthcare systems, which may lead to incorrect diagnosis, and lack of effective treatment, resulting in higher mortality statistics. Overall however, I believe there is a strong enough link between lifestyle factors and cancer. It is vital that people abstain from smoking, excessive alcohol consumption and UV sun exposure, in order to minimise the risk of contracting these cancers. Obviously however, lifestyle factors are not the sole causes of these diseases, and no lifestlye would ever provide 100% protection.
- Discuss medical developments in the treatment of cancer (6 marks)
In recent years, the treatment of cancer has become more effective and efficient. In 1971-75, around 82% of females survived breast cancer. By 2000-1, this percentage was at 96%. For Prostate cancer, the figure was 65%, and is now 91%. These increases represent the innovation in cancer treatment.
One such treatment is the use of Monoclonal Antibodies. These are types of antibodies made in the laboratory, and based on a single human antibody. Monoclonal antibodies are designed to recognise specific, abnormal proteins present on cancer cells. Each antibody recognises one particular protein, as proteins are different for each cancer.
Several different monoclonal antibodies are currently being used to treat cancer, and this is an exciting development, as unlike Chemotherapy, other body cells are not damaged. However it is a long process, as the antibodies are difficult to produce.
Monoclonal antibodies can work in three different ways to destroy the cancer. Firstly, the Antibody can trigger an immune response to attack and destroy the cancer cells. Normally, it is hard for the immune system to locate cancer cells, as cancers develop from normal, existing cells. By attaching to the proteins, the antibodies allow the immune system to quickly detect the cancer.
Some antibodies can carry cancer drugs to the cancer cells. This works by attaching radiation to the antibodies in the lab, and then injecting them into the patient intravenously.
Monoclonal antibodies can also be used to stop cancer cells from taking up proteins. These antibodies work by seeking out cells which mutate too much. The antibody then connects to the cancer cells, blocking its receptors. Herceptin, a new Breast Cancer drug works in this way.
Herceptin has been shown as a promising drug for Breast Cancer. At the site of this Cancer, there is sometimes an excess of the gene HER2, which makes a protein known as a HER2 receptor. It is this protein which Herceptin attacks; the monoclonal antibodies in the drug attach themselves to the HER2 receptors on the surface of the breast cancer cells. The result of this is that the breast cancer growth can no longer send or receive signals, and therefore the cancer is slowed down. In addition to blocking HER2 receptors, Herceptin also works to alert the immune system, which can then help to attack the cancer.
One problem with Herceptin is that it is only effective when there is an excess of HER2; in other words, the patient needs to be HER2-positive. Some Breast Cancers do not produce an excess of the gene, and so more conventional treatments must be used. Only around 20% of Breast Cancers are HER2-positive.
Another issue with Herceptin is cost and availability. Currently, Herceptin is not available on the NHS everywhere in the UK. This is because of huge cost of £22,000 per patient to be treated with Herceptin; this cost is much higher than the average cost of Chemotherapy, which can cost under £1000 for an 8-week course.

It is currently a huge debate whether Herceptin is cost effective. This graph shows the median time to progression of the Breast Cancer, in a patient treated with Herceptin and Chemo, and Chemo alone. As it clearly shows, patients treated with Herceptin will have a 60% increase in the time before their cancer progresses; up to an additional 7 months.
This second graph also demonstrates the 1-year survival figure. We can see that 79% of patients survive the one year point, when using both Herceptin and Chemo. This is compared to only 68% when using Chemo alone. The figures are similar to the use of Herceptin with Paclitaxel (another existing cancer treatment), or Paclitaxel alone.
Finally, Herceptin also provides benefit to patients, helping to stop recurrence of Breast Cancer. The graph shows that Herceptin and Chemo (Pink) almost halves the probability of the Cancer recurring, compared to Chemo alone (Grey).

The use of monoclonal antibodies in cancer treatment is a promising and exciting development. Already, the science has been used to create the life preserving drug Herceptin. While there is a cost issue, it is very clear from the evidence that Herceptin is a very promising treatment, compared to Chemotherapy alone. Herceptin helps to delay the growth of breast cancer for 60% longer on average than just Chemotherapy. It also helps to stop reoccurrence, and offers improved one year survival. Herceptin is however a vastly expensive drug, and is only useable in 20% of cases. The overall answer comes down to an ethical debate; is preserving life cost effective? I believe that Herceptin should be offered on the NHS to those who need it; while cost is an important issue, preserving life must be the sole priority in any healthcare system that is truly centred on the patient.
JK