Cancer

Cancer is an uncontrolled proliferation of cells inside the body. These cells have an abnormal mitotic cycle causing them to grow uncontrollably, leading to tumours, and thus a disease state. Hanahan and Weinberg's Hallmarks of Cancer is a much-cited paper that is useful for defining cancer and understanding the six traits that many different cancer types have in common^[1]. The study and treatment of cancer is known as oncology.

Contents 1 Causal factors 2 Treatment of Cancer 3 Hallmarks of a cancer cell 4 References

Causal factors

There are many different forms of cancer associated with every organ in the body from the extremely rare (heart cancer) to the four most common cancers (prostate, lung, breast (women) and colon). The causal factors in cancer vary wildly from genetic predisposition to environmental carcinogens with the exact makeup of these carcinogens is highly disputed, but some are widely accepted as cancer-causing. Radiation, environmental toxins, UV, obesity, viruses and chemical carcinogens such as benzene. Equally, cancers can be very age-specific such as retinoblastoma, which tends to affect the very young. Testicular cancer which tends to affect the 16-25-year-old categories and prostate cancer which is a very common in the 60-80-year-old category (fig 1 and 2)^[2][3]. Genetically predisposed individuals will often develop cancer more severely and often earlier in life. Whereas people from different ethnic backgrounds can have very different cancer incidence curves. This is due to differential genetics between populations and the lifestyles changes that can be seen between countries (fig 3)^[4]. The Japanese populous have higher rates of colon and lung cancer compared to England in the ~ 30 – 70 age category but by 80 England has nearly caught the rate up. So as you can see there are many factors and differentials related to cancer and its incidence. Old age cancers can strike in the prime of life and childhood cancers can develop late. It is a worldwide issue of great importance and will continue to be far into the future^[5]. A cancerous cell is generated by multiple independent mutations that have all been missed by intrinsic cell control mechanisms. Cancers can be induced by mutagens or instead by oncogenic viruses^[6].

Treatment of Cancer

The treatment of cancer had developed greatly over the last few years. Firstly, there are some screening techniques used to catch cancer before it has time to properly develop. These include mammography to screen for breast cancer as well as smear tests to screen for cervical cancer^[7]. In the UK at this time, these techniques are given as standard to women over a certain age, smear tests are given out to women once they reach the age of 25. In the majority of cancer cases however the patient detects the symptoms and will then relay these to a doctor who can make a diagnosis^[8]. The three main areas of cancer are surgery, chemotherapy and radiotheraphy. Depending on the type and severity of cancer depend on which of these are used and often a combination of all of them are required^[9].

Surgery is one of the main treatments for cancer. It might be the only treatment you need. It is a local treatment – it only treats the part of the body operated on. So it may cure cancer that is completely contained in one area and hasn't spread. Usually, the earlier a cancer is found the easier it is to remove it^[10].

When cancer has progressed and surgery cannot be completed, chemotherapy and radiotherapy are the main opportunities for treating cancer. However, treatment with chemotherapy and radiotherapy is damaging for healthy cells too. Thus, the targeted anti-cancer drugs are promising in cancer treatment, these drugs target only cancer cells^[11]. For instance, cancer cells distinguish by an active action of protein kinases. Thus, targeting kinases is advantageous^[12].

Many treatments, however, can come with side effects. For example, Chemotherapy can result in the patient feeling fatigue, nausea and hair loss (although there is a cold cap which can be used to prevent hair loss, this can only be used with certain cancers)^[13]. Radiotherapy can result in sore skin, tiredness and loss of appetite and surgery can come with its own problems and complications, including infection.

Hallmarks of a cancer cell

From research, there have been 6 characteristics that have been identified in all cancer cells^[14][15].

1. They create their own growth signals, so are self-sufficient. This means that they can proliferate indefinitely.
2. Tumour suppressor genes are mutated, causing the tumour suppressor proteins to not function correctly.
3. Evading apoptosis, cancer cells have the ability to evade cell death.
4. Sustained angiogenesis, the ability to create new blood vessels meaning the cells will obtain sufficient nutrients and oxygen for growth.
5. Limitless replicative potential, the cancer cells obtain this trait via the synthesis of telomerase, an enzyme that replenishes the telomeres at the end of chromosomes.
6. Metastasis, where cancer cells break off from the main site and travel to other areas of the body. This is usually associated with late stage cancer.

References

1. ↑ Hanahan D, Weinberg RA, 'Hallmarks of Cancer: The Next Generation' Cell 144 p646-674, Cell. Available at http://www.cell.com/cell/abstract/S0092-8674(11)00127-9 Last accessed on 24 October 2014.
2. ↑ Dynamics of Cancer: Incidence, Inheritance, and Evolution.Frank SA.Princeton (NJ): Princeton University Press; 2007. chapter 2, fig 2.2
3. ↑ Dynamics of Cancer: Incidence, Inheritance, and Evolution.Frank SA.Princeton (NJ): Princeton University Press; 2007. chapter 2, fig 2.4
4. ↑ Dynamics of Cancer: Incidence, Inheritance, and Evolution. Frank SA.Princeton (NJ): Princeton University Press; 2007. chapter 2, fig 2.21
5. ↑ Parham, P. The immune system. 4th Ed, New York: Garland Science. 2015
6. ↑ Parham, P. The immune system. 4th Ed, New York: Garland Science. 2015
7. ↑ Roger J. King, Mike W. Robins (2006). Cancer Biology. 3rd ed. Essex: Pearson. p230-62.
8. ↑ Roger J. King, Mike W. Robins (2006). Cancer Biology. 3rd ed. Essex: Pearson. p230-62.
9. ↑ Roger J. King, Mike W. Robins (2006). Cancer Biology. 3rd ed. Essex: Pearson. p230-62.
10. ↑ 8 Cancer Research UK, Last updated 4, April 2016, available at http://www.cancerresearchuk.org/about-cancer/cancers-in-general/treatment/surgery/surgery-to-treat-cancer#ZHp2XowRyqpib6lm.99References
11. ↑ Uwe Marc Martens. Small Molecules in Oncology. 2nd Ed., Berlin: Springer. 2014
12. ↑ Claudio Raimondi, Veronique Calleja, Riccardo Ferro, Alessandro Fantin, Andrew M.Riley, Barry V.L. Potter, Caroline H. Brennan, Tania Maffuci, Banafshe Larijani, Marco Falasca. A Small Molecule Inhibitor of PDK/PLCγ1 Interaction Blocks Breast and Melanoma Cancer Cell Invasion. Scientific Reports 2016; 6, 1:1-14
13. ↑ http://www.nhs.uk/Conditions/Chemotherapy/Pages/Side-effects.aspx
14. ↑ Mukherjee, S. (2012). Emperor of all maladies. Thorndike Press.
15. ↑ Hanahan, D. and Weinberg, R. (2000). The Hallmarks of Cancer. Cell, 100(1), pp.57-70.