Not finished as I got bored - might be helpful however? xxx

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Cancer describes

a disease characterised by uncontrolled

growth of cells typically resulting in a tumour (except in the case of leukaemia).

Such a disease arises once genes suffer a sufficient number of changes and

mutations so as to disrupt cell growth. Age

is the single biggest factor for cancer – two

thirds of all cases of cancer are in the over 65s because the longer an

individual is alive, not only are they exposed

to more factors that lead to genetic mutations, but individual’s become less able to correct any mistakes made.

Normal cells have their growth

regulated by contact inhibition of

movement, density dependent inhibition of growth, adhesiveness, anchorage

dependence and growth factors.

Cancerous tumours grow in spite of these “regulations” and their growth is

dependent upon tumour growth rate

(how quickly old cells are replaced by new cells), having an adequate blood supply and in the case of hormone-linked

tumours, having an adequate level of

hormones.

However, an abnormal cell and a tumour is not indicative of cancer.

A neoplasm or “new growth” is an

abnormal growth that is no longer subject to normal homeostatic controls. A

neoplasm may be benign or malignant; a benign tumour occurs when

a neoplasm develops in a restricted

space, where they metabolise and

mature normally and are rarely fatal.

Schwannoma are benign growths

that form from the Schwann cells of nerves. The tumours themselves are not

fatal, however if they grow to a sufficient size they may result in nerve compression

or damage, ischemia or necrosis. A malignancy is unable to perform specific

tasks, an infinitive proliferative lifespan, uncontrolled metabolism and a high

nutrient demand.

There are 5 main differences between benign and malignant

tumours: Benign tumours are usually encapsulated,

malignant ones are not; benign tumours have a low mitotic rate, malignant tumours have a high one; benign tumours are

well differentiated, malignant ones

are not; benign tumours are unable to be invasive

or metastasise unlike malignant tumours.

The metastasis of a malignant tumour is the development of

secondary tumours originating from the original malignancy in a new location. This

may occur from part of the tumour breaking off into the local area where it may

be transported to another part of the body in the lymph or blood; where in the

latter case the malignant cell(s) move in and out of the blood vessel by intravasation

and extravasations.

Malignant tumours or cancer are the result of an

accumulation of genetic mistakes for which there are several risk factors

asides age including diet, hormones, UV exposure, family history and smoking. Salt is

thought to irritate the lining of the stomach, leading to inflammation and

creating conditions where mutations may arise; red meat contains nutrasamines, which are carcinogenic. On the

other hand, caretenoids, antioxidants,

flavanoids, phytochemicals and fibre are considered beneficial

constituents of diet. Natural hormone levels change over time and lead to an

increase in certain cancers at certain ages; encochrone-disrupting chemicals

are found in pesticides and mimic the effects of hormones increasing the incidence

of hormone-related tumours. Excessive UV exposure can

cause genetic mutations to DNA that can lead to skin cancer. Some tumours have

a very strong genetic link, for example BRCA and breast cancer and S100 and

benign scwannoma. Finally smoking has a strong association with cancers. As

well as the pathological effects smoking has not associated with cancer

(cecreaseing haemogloban availablility to oxygen) the smoke paralyses the cilia

in the respiratory tract and eventually (reversible) squamous metaplasia takes place replacing the

epithelial cells. This may lead to further changes to the cell including size

and number, known as dysplasia (or

precancer). Further damage can lead to cancer.

If this cancer

occurs on the epithelium, the result is a carcenoma

Not finished as I got bored - might be helpful however? xxx

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