Cancer intro

ONCOLOGY

1. cancer Ratheesh R L

2. DEFINITION A term for diseases in which abnormal cells divide without control and can invade nearby tissues.

3. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.

4. Leukemia is a cancer that starts in blood-forming tissue, such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood . Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system.

5. Normal cell structure

6. - Cancer cells are self sufficient on growth factors: This means that they can continue to proliferate and divide independently, as opposed to normal cells that need external growth factors . - They can resist inhibitory signals that normally come from neighboring cells . - Resisting apoptosis is also a crucial attribute of a cancer cell. - Stimulation of angiogenesis is very important since the rapidly growing cancer needs a high amount of oxygen and nutrients. The stimulation of angiogenesis also serves as a way of metastasis

7. - Can multiply forever : Normal cells go through senescence through e.g. shortening of telomeres with every cell division. Cancer cells however have telomerase that will sustain the telomere length of the chromosomes rendering the cell virtually immortal . - Invade local tissues and metastasize : This means that the cancer cells spread throughout the body by sending out pioneer cells that can form new metastases.

8. Difference between normal cells and cancer cells

9. Difference between normal cells and cancer cells morphology Normal cells have uniform  shapes and sizes Cancer cells have a large variety of sizes and shapes The nucleuses have irregular structure and have relatively small cytoplasm.

10. Reproduction and Cell Death Cells stop dividing when too much of its kind are present. These cells grow and divide in a controlled manner and follow a predictable life cycle. Normal cells undergo the process of apoptosis – self destruction if they detect abnormalities and damage in their organelles. Cancer cells don’t stop growing resulting to appearance of a tumor ( a cluster of mutant cells)

11. Communication Normal cells communicate with each other for proper functioning. Cancer cells do not communicate with each other.

12. Adhesion and Invasion These cells have external membranes that allow them to bond with other cells These cells have the ability to invade or spread to other parts of the body by travelling through the blood stream or the lymphatic system – metastasis

13. Specialization Normal cells start out as immature cells and mature with certain specialized functions. Cancer cells do not mature, and undergo apoptosis. Instead these cells become immature overtime. Cancer cells are primitive and they don’t have specialized functions

14. Signal Recognition Normal cells recognize signals. They know when there are enough new cells and stops dividing. Cancer cells don’t recognize signals. Hence these cells erratically reproduce mutated cells.

15. WARNING SIGNS OF CANCER To remember the seven early warning signs of cancer, think of the word CAUTION C hange in bowel or bladder habits. A  sore that does not heal. U nusual bleeding or discharge. T hickening or lump in the breast, testicles, or elsewhere. I ndigestion or difficulty swallowing. O bvious change in the size, colour , shape, or thickness of a wart, mole, or  mouth sore . N agging cough or hoarseness.

16. The following symptoms may also indicate the presence of some form of cancer: Coughing-up blood Persistent headaches Unexplained loss of weight or appetite Chronic pain in bones Persistent fatigue, nausea, or vomiting Persistent low-grade fever, either constant or intermittent Repeated instances of infection

17. EARLY DETECTION AND SCREENING OF CANCER Early detection of cancer greatly increases the chances for successful treatment. There are two major components of early detection of cancer: education to promote early diagnosis and screening . Recognizing possible warning signs of cancer and taking prompt action leads to early diagnosis. Increased awareness of possible warning signs of cancer, among physicians, nurses and other health care providers as well as among the general public, can have a great impact on the disease. 

18. Some early signs of cancer include lumps, sores that fail to heal, abnormal bleeding, persistent indigestion, and chronic hoarseness. Early diagnosis is particularly relevant for cancers of the breast, cervix, mouth, larynx, colon and rectum, and skin .

19. SCREENING OF CANCER Screening refers to the use of simple tests across a healthy population in order to identify individuals who have disease, but do not yet have symptoms. Examples include breast cancer screening using mammography and cervical cancer screening using cytology screening methods, including Pap smears.

20. Screening programmes should be undertaken only when their effectiveness has been demonstrated, when resources (personnel, equipment, etc.) are sufficient to cover nearly all of the target group, when facilities exist for confirming diagnoses and for treatment and follow-up of those with abnormal results, and when prevalence of the disease is high enough to justify the effort and costs of screening.

21. Based on the existing evidence, mass population screening can be advocated only for breast and cervical cancer, using mammography screening and cytology screening, in countries where resources are available for wide coverage of the population. 

22. Several ongoing studies are currently evaluating low cost approaches to screening that can be implemented and sustained in low-resource settings. For example visual inspection with acetic acid may prove to be an effective screening method for cervical cancer in the near future. More studies that evaluate low cost alternative methods to mammography screening, such as clinical breast examination, are needed.

23. PREVENTION OF CANCER Tobacco Tobacco smoking causes many types of cancer, including cancers of the lung, oesophagus , larynx (voice box), mouth, throat, kidney, bladder, pancreas, stomach and cervix. About 70% of the lung cancer burden can be attributed to smoking alone. Second-hand smoke (SHS), also known as environmental tobacco smoke, has been proven to cause lung cancer in nonsmoking adults.

24. Physical inactivity, dietary factors, obesity and being overweight Dietary modification is another important approach to cancer control. There is a link between overweight and obesity to many types of cancer such as oesophagus , colorectum , breast, endometrium and kidney. Diets high in fruits and vegetables may have a protective effect against many cancers. Conversely, excess consumption of red and preserved meat may be associated with an increased risk of colorectal cancer. In addition, healthy eating habits that prevent the development of diet-associated cancers will also lower the risk of cardiovascular disease.

25. Regular physical activity and the maintenance of a healthy body weight, along with a healthy diet, will considerably reduce cancer risk. National policies and programmes should be implemented to raise awareness and reduce exposure to cancer risk factors, and to ensure that people are provided with the information and support they need to adopt healthy lifestyles.

26. Alcohol use Alcohol use is a risk factor for many cancer types including cancer of the oral cavity, pharynx, larynx, oesophagus , liver, colorectum and breast. Risk of cancer increases with the amount of alcohol consumed. The risk from heavy drinking for several cancer types (e.g. oral cavity, pharynx, larynx and oesophagus ) substantially increases if the person is also a heavy smoker.

27. Infections Infectious agents are responsible for almost 22% of cancer deaths in the developing world and 6% in industrialized countries. Viral hepatitis B and C cause cancer of the liver; human papilloma virus infection causes cervical cancer; the bacterium Helicobacter pylori increases the risk of stomach cancer. In some countries the parasitic infection schistosomiasis increases the risk of bladder cancer and in other countries the liver fluke increases the risk of cholangiocarcinoma of the bile ducts. Preventive measures include vaccination and prevention of infection and infestation.

28. Environmental pollution Environmental pollution of air, water and soil with carcinogenic chemicals accounts for 1–4% of all cancers (IARC/WHO, 2003). Exposure to carcinogenic chemicals in the environment can occur through drinking water or pollution of indoor and ambient air.

29. Occupational cancinogens : Occupational cancers are concentrated among specific groups of the working population, for whom the risk of developing a particular form of cancer may be much higher than for the general population. About 20–30% of the male and 5–20% of the female working-age population (people aged 15–64 years) may have been exposed to lung carcinogens during their working lives, accounting for about 10% of lung cancers worldwide. About 2% of leukaemia cases worldwide are attributable to occupational exposures.

30. Radiation: Residential exposure to radon gas from soil and building materials is estimated to cause between 3% and 14% of all lung cancers, making it the second cause of lung cancer after tobacco smoke . Ultraviolet (UV) radiation, and in particular solar radiation, is carcinogenic to humans, causing all major types of skin cancer, such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma.