Cancer is a disease that is defined as a abnormal and uncontrolled growth of cells. Cancer is a generic term for malignant neoplasms. The basic characteristic is the loss of control over growth and function of cells resulting in serious and life threatening adverse effects. It can be mentioned that in Europe and South America, over 90% of all cancers are lung ,colo-rectal and breast cancers attributed mainly to inappropriate lifestyle. In Africa, liver cancer stands out due to hepatitis B, cervical cancer in undeveloped countries where birth rate is high but higyne is poor resulting therefore high levels of sexually transmitted diseases (papillomavirus, herpes), that can be become cancer triggers.
Causes of cancer
Cancers can be caused by exposure to viruses, exposure to natural or chemical substances, radiations and many more as seen in the picture below. The effects are multiple mutations or inadequate expression of different genes called oncogenes involved in cell proliferation, cell differentiation and adjustment. The oncogenes normally are kept under strict control by the tumor suppressing genes but the effect can be lost or suffer mutations like described above. In some cases these suppressing genes do not exist at birth, fact that explains family predisposition to certain types of cancer.
Alcohol. Drinking is a risk factor for mouth cancer, pharynx cancer, cancer of the esophagus, and of course liver cancer (the risk varies between 2 and 15% depending on the quantity consumed and targeted organs). Smoking combined with drinking coresponds to way higher risks than the sum of risks taken for each considered alone (multiplicative effect).
Eating Habits. Many studies have analyzed the relation between eating and the appearance of different types of cancer. Foods rich in fat, foods that lack fibers and vitamins or contaminated (aflatoxin, nitrites) can be blamed. Studies have shown that the risk raises paralel with consumption of rich in fat foods.Protective feature were seen in the case of vegetables and fruits. Nitrates found in salt, used for conserving aliments, are blamed for raising the risk of stomach cancer. The aflatoxin found in foods stored in wet and warm environments is responsible for primitive liver cancers, associated with infection with hepatitis B virus.
Irradiation. In 1944, a publication revealed the fact that radiologysts died 10 times more frequent from leukemia than other medics. In the case of Hiroshima and Nagasaki bombardment survivors back in 1945, the first cases of leukemia were noticed in 1951 and culminated in 1952. Other types of cancer were observed after 15 years from exposure, and some of them can be seen even today, at survivors who recieved more than 1Gray (unit used for measuring the absorption of one joule of energy, in radiation form).
Diseases. Some rare diseases are considered high risk factors for cetain organs (retinoblastoma, 21 trisomy). They can give birth to malignant tumors like retinoblastoma, nefroblastoma or determine non malign effects but with high risk for malignant conversion (colic polyposis).
Carcinogenic Drugs. Dietilstilbestrol (estrogen), immunosuppressants, arsenic compounds, even some anti-cancer drugs can be added here.
Family Predisposition. For some types of cancer the family predisposition is present, family members of a person affected by colon cancer, ovary cancer, breast cancer, have a doubled risk of developing the same type of cancer. The explanation can be found in their genome combined with specific environmental factors.
Solar Radiation. Tanning habits of the last decades are accompanied in all countries by a high incidence in skin cancers, carcinomas and melanomas. The effects of U.V.B radiation are very well known.
Carcinogenic Substances. In 1975, a direct relation was established between bladder cancer and the dyestuff industry. From 707 substances tested 23 have been proven to be carcinogenic.
Tobacco. We all know this, nothing new here. Tobacco is responsible for 90% of the pulmonary cancers. The cancer risk is greater for heavy smokers, long term smokers, and for persons who started smoking at early ages.
Viruses. The role of retroviruses is well known now. Only H.I.V and HTLV seem to have oncogenic potential. ADN viruses: Epstein-Barr (Burkitt lymphoma), Hepatitis B or HBV ( primitive liver cancer), Papilloma Virus HPV (cervical cancer).