explain the development of cancer disseases?

explain the development of cancer disseases?
Answer:
Cancer develops when there is a constant irritation to a body's organ whether it be skin (irritated by sun), lungs (irritated by some pollutant), cervix (irritated by HPV), etc.This constant irritation causes rogue cells. Cells that grow too fast, that don't follow the "rules" of normal development. As they grow, they take the nutrients away from the normal cells. The normal cells die, the rogue or cancer cells proliferate. But because cancer grows so quickly, it also dies more easily than normal cells. Thus it will die first when chemotherapy is introduced.

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The Development of Cancer disseasesMultistage CarcinogenesisThe elderly are more susceptible to cancer than other groups because it is a multistage process that may take 15-45 years before clinical signs are evident. Cancerous growth forms as the result of a sequence of events over a period of time. The events are associated with the exposure of DNA to harmful molecules originating from within or outside of the body. Researchers suggest that an average of five or six chemical insults to susceptable genes will lead to cancer. Some people are genetically susceptible to cancer because enzymes which help to prevent cancer growth are not efficient or enzymes that may contribute to cancer formation are very active.There are three phases of development involved in the formation of cancerous growth.The first stage consists of a mutation of DNA which does not undergo DNA repair (by enzymes) or undergoes faulty DNA repair.The second step is promotion which involves an action promoting the uncontrolled growth and proliferation of mutated cells. In time these cells loose their normal abilities and just reproduce.The third step is metastasis. This is the invasion of cancerous cells into nearby tissues as well as the migration of cancerous cells to other tissues via circulatory or transport systems.Substances introduced to the body can cause mutation, promotion , or both. A carcinogen which causes both is called a 'complete carcinogen'. Physical damage to tissues can cause cell proliferation. Some mutagens can damage surrounding tissues, leading to cell proliferation. This may also lead to cancer.These events invariably occur naturally over time as we are exposed to man-made environmental contaminants and toxins that occur naturally in our food, in minerals, and in our bodies as oxidative by-products of metabolism.Examples of naturally occurring carcinogens include aflatoxin, a by-product of mold found in peanut butter; isocyanate, found in brown mustard; estragole from basil; nitrosamines from cooked bacon; and benzo(a)pyrenes found in charred or barbecued foods.

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There are four major phases of tumor formation. Each phase can take years to complete. The first one alone usually takes anywhere from 15 to 30 years.The first phase occurs when normal cells mutate into tumor cells and begin dividing out-of-control. This may take place over successive generations of cells. When just the right mutations occur, the cells will divide and grow to a small tumor.The second phase is called Carcinoma in situ. This phase is classified by the presence of a cancerous tumor that has not yet invaded other tissues. This phase usually lasts between 5-10 years and is limited by the nutrient flow to the tumor. If blood vessels can be induced to grow into the tumor (angiogenesis), the tumor will progress to the next phase, called the invasive stage.The invasive phase can happen rapidly, requiring only a few months. However, in some cases it may take up to five years. This phase is dependent on the ability of the tumor to invoke nearby blood vessels to grow toward it and provide it with nutrients - commonly referred to as angiogenesis.Metastasis, or dissemination to other tissues if the final phase. This phase has the same time period as the invasive phase, ranging from a few months to five years.At each phase, the cancer can either progress further or altogether diminish. If you add each phase up, the average for the cell mutating events and cancer diagnosis is 20-50 years apart. This is why cancer mostly affects older people. Actually, half of all cancers are diagnosed after the age of 65.

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A carcinogen causes damage to the oncogene. this gene is responsible for regulating cell growth. when it is damaged cells begin to grow erratically.

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