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How Does Cancer Start?
Over 42% of all males and 39% of all females are presently likely to develop cancer at some time in their lives. Topping th list of cancers for men are canceres of the prostate (12%), lung (9%) and colorectal cancer (6%). For women the most common cancers are brast cancer (12.5%), colorectal (6%) and lung (5%). Recently the effects of asbestos exposure have been surfacing in numerous cases of Mesothelioma cancer.
Initiation and Proliferation
Cancer is a disease characterised by uncontrolled virulent growth of poorly differentiated cells. Neoplastic (abnormal) cells are initiated, proliferate and expire by certain mechanisms that have been partially defined. Initiation involves changes in the cellular DNA, which can be caused by viruses, chemicals, or radiation.
In the initiation stage a carcinogenic agent contacts a normal cell and alters the DNA. This stage can be reversible because the body maintains several processes that can repair damaged DNA.
Regardless of the immediate cause of cancer, it is a fact that body pH is the underlying factor of cancer proliferation. Just as bacteria, viruses, fungi and all disease-producing organisms flourish in an acidic medium and die in alkaline conditions, the same is true of Cancer cells. So once our body pH starts to drop below neutral, we are opening the door for disease, including cancer, right there.
After initiation, the precancerous cell remains indistinguishable from normal cells until a promoting agent stimulates it into neoplasia (abnormal growth).
Dietary factors and contaminants such as dioxin, PCBs and evn high caloric content, high fat content and high protein content in the diet are able to increase tumour response in carcinogen-treated animals. If the agent is not itself carcinogenic, but increases incidence or speed of tumour growth, it is termed a tumour promoter.
Invasion
Invasion is the infiltration of tumor cells into adjacent tissues. The first evidence of tumor invasion is destruction of the underlying basement membrane giving the tumor access to the underlying connective tissues. Basement membranes are composed mainly of type IV collagen.
Invasiveness of tumors depends on the tumor's ability to produce collagenase IV. Inhibitors of collagenase can inhibit tumor invasion and metastasis (spreading).
Hormones and Growth Factors
Hormones and other hormonal factors including eicosanoids and growth factors regulate cell function and are important in abnormal growth. Tumors may be responsive to or even depend upon stimulation by sex hormones. These include breast, endometrial and passive tumors.
Agents that reduce oestrogen bioavailability in females include camelia sinensis (green tea), fibre, genistein (brooms), hops, lignans, phytoestrogens, and dietary fat reduction. Agents that decrease dihydrotestosterone production in men include saw palmetto, zinc and epilobium.
Eicosanoids also play a variety of roles in the initiation, promotion and progression of cancer. Tumors synthesize through both the cyclooxegenase and lipooxegenase pathways. The lipoxygenase pathway of arachidonic acid is important for tumor production and PGE induced inflammation may relieve tumor invasion and angiogenesis. Omega-3 oils compete with arachidonic acid to cause a reduction in the inflammatory response.
Growth Factors such as fibroblast growth factor and insulin-like growth factor regulate cell maintnance, differentiation, proliferation and other functions. Growth factors mediate such functions by binding to membrane receptors containing tyrosine kinases. Natural agnts that inhibit tyrosine kinase activity include genistin and flavonoids such as quercetin.
The Immune System
The human immune systm functions along two separate but interrelated branches known as humoral immunity and cellular immunity. Cellular immunity includes the action of T lymphocytes, NK clls, and macrophages, and is the branch most associated with anticancer activity. The immune system may limit carcinognesis by destroying newly transformed cells in a process known as immune surveillance, and may also limit the growth of established tumors depending on the size of the tumors, their antigenicity and their immunogenicity.
The majority of human tumors exhibit high antigenicity but low immunogenicity, partly due to their ability to evade detection by promoting blocking factors and other mechanisms. Because of this the human immune system is generally unable to produce cancer remission without assistance.
Assitance can consist of active or passive immunotherapy. However even with immunotherapy, remission and cure rates have been rather low. New therapies and combinations of therapies may provide improved results in the future. A large number of natural agents may either stimulate or inhibit various aspects of the immune system and some agents may be capable of doing both.
For Causes and Aids READ ON.
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