Cell division is a normal process in all living beings. Except the liver & the brain cells, which rarely divide in the mature adult, most cells undergo frequently division. Sometimes, however, cell division becomes very rapid & uncontrolled leading to cancer. The cells which undergo rapid, abnormal & uncontrolled growth in comparisons to remaining cells are called "Neoplastic cells" & the growth from such cells are called "Neoplastic growths" or "tumors". Tumors are commonly classified as:
1. Benign Tumors: They are always localized & consist of well differentiated cells. They do not spread, are generally harmless & thus can be removed by surgical operation. However, these tumors may sometimes become quite harmful if they are located in organs like brain & liver.
2. Malignant Tumors: They are infact "cancerous growths" & consist of usually undifferentiated cells. They are invasive & spread rapidly by blood stream or by lymphatic system or by direct penetration to other parts of the body.
Types of cancer:
Cancer is not a single disease but a complex of many diseases. About 200 distinct types of cancer have been recognized. They can be grouped into four main types:
1. Carcinomas: They constitute about 85% of total cancers. Examples are cervical, breast, skin, brain cancers etc.
2. Sarcomas: They constitute only about 2% of human cancers. Examples are tumors of cartilage, bone, muscle etc.
3. Lymphomas: They constitute about 5% of human cancers. Best example may be taken as "Hodgkin disease".
4. Leukemia: They constitute about 4% of human cancers. Example is blood ie, (Leucocytes- WBC) cancers.
Free radical attacks directly to the cells, penetrates them & gradually reaches to the DNA where it attacks genes & disturbs gene coding. In this way, free radical alters the whole of the characters of a cell. Disturbance of gene coding results in the formation of tumor which is the major symptom of cancer.
Professors Dorothy & James Morre of Purdue university of USA found that tumor cell gets rapidly increased with the help of two enzymes.
1. t-NOX (tumor associated nor-oxidize)
2. Urokinase
These enzymes boost up the tumors to form carcinogenic cells of cancer.
EGCG of green tea prevents cancer in two ways:
1. Anti-oxidant property of EGCG captures free radical & hence decreases the chances of formation of cancer.
2. EGCG of green tea makes both of these enzymes inactive such that carcinogenic cells can't form easily. Small numbers of these tumor cells are slowly removed by immune system of the body itself as well as by the programmed cell death (apoptosis).
World-wide research studies, including epidemiological & histological tests, undertaken in the past one decade suggests that the anti-oxidants in tea could play a role in human cancer risk reduction possibly by combating free radical damage, inhibiting uncontrolled cell growth (cell proliferation) & by promoting programmed cell death (apoptosis). Leading scientists world-wide are actively studying, these potential mechanisms & clinical trials & population studies are underway.
There are promising preliminary studies regarding the correlation of tea consumption & the risk of certain types of cancer including breast, lung, ovary, & skin cancers & cancer of the mouth.
Abundant experimental & epidemiological evidence accumulated mainly in the past decade from several centers world-wide provides a convincing support that polyphenolic anti-oxidants present in tea can reduce cancer risks & tumors.
- US FDA (Food & Drug Administration) announces that green tea may reduce the risk of certain types of cancer.
(FDA News, June 30, 2005)
- According to the research of Kyushu University of Japan, EGCG of green tea protects from different types of cancer including lung, prostate & breast cancer.
Researchers found that function of lung cancer receptor called
67LR was also slowed down by EGCG.
- US National Cancer Institute found that catechins of green tea inactivated oxidants before cell damage occurred, reduced the number & size of tumors & inhibited the growth of cancer cells.
- Study from the "oxford Life Science" found that green tea is effective in suppressing breast cancer growth & Breast cancer tumors.
- Professor Roger Thornely of John Innes Center of Norwich, England & other Researchers of the University of Murcia (Spain) separately have shown that EGCG of green tea prevents cancer from growing by binding to a specific enzyme called Dhydrofolate reductase. This enzyme is responsible for the production of tumor cells of cancer & anti-cancer drug is mainly based to inactivate this Dihydrofolate reductase enzyme.
--Reuters (March, 2005)
- Researchers in UK discovered that drinking green tea has a capacity to inhibit ultraviolet B-light-induced skin cancers.
- Researchers at the cancer chemotherapy center in Tokyo, Japan have found that Epigallo catechin gallate (EGCG) of green tea strongly & directly inhibits ateliers. ATELIERS are the enzyme that "immortalizes" cancer cells especially in Leukemia & colon cancer.
- According to the researchers at the Mayo Clinic of USA, green tea's EGCG helps to destroy leukemia cells. They found that EGCG was able to destroy 80% of the cancer cells.
Although there is currently no cure for chronic Lymphocytic Leukemia (CLL), severe cases are treated with chemotherapy. Now the doctors are quite hopeful by finding such a new & non-toxic Leukemia treatment with the help of EGCG of green tea.
--Lee YK: Bone ND.& friends
(Blood, 2004)
- Japanese researchers recently have reconfirmed that green tea is highly effective in inhibiting most of the cancers. Green tea is a regular beverage in Japanese diet. It is interesting that Japanese have both the highest smoking rate & lowest lung cancer rate in the industrialized world.
- Ultra-voilet radiation is known to cause inflammation, making the skin more Susceptible to cancer.
- In a study done by Norris Comprehensive Cancer Center, University of Southern California (USA) shows that high doses of EGCG & other catechins of green tea are particularly effective in preventing inflammation & skin cancer. Recently on Dec.27, 2006, researchers from University of California & from Oxford Life Science separately found that green tea is effective in suppressing breast cancer.
- According to Professor Takuo Okada of Japan, the polyphenols in green tea appear to reduce the risks of certain cancers. Green tea contains a powerful anti-oxidant called Epigallo catechin gallate (EGCG) which controls the activity of free radicals, the unstable compounds that can destroy cells.
