The main polyphenol in green tea is epigallocatechin gallate (EGCG). Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anticancer properties that may help prevent the onset and growth of skin tumors.

ScienceDaily (Dec. 1, 2006) — Tea extracts work as an effective treatment for patients who suffer from damaged skin following radiation treatment for cancer. Researchers show that this might partly be due to the anti-inflammatory properties of tea. In a study published in the open access journal BMC Medicine, researchers show that tea acts at the cellular level, by inhibiting inflammatory pathways, to reduce inflammation. They also show that tea extracts reduce the duration of radiation-induced skin damage by up to 10 days in patients who received radiation treatment. Frank Pajonk, from the University of California in Los Angeles, USA, and colleagues from the University of Freiburg, Germany, studied the effects of green tea and black tea extracts on patients who had been treated with radiotherapy, which can damage the skin. The authors then analysed the effects of the same tea extracts on human and mouse white blood cells in culture. Pajonk et al. find that tea extracts reduce the duration of skin toxicity following radiotherapy by 5 to 10 days. Green tea extracts are more effective than black tea extracts in some patients. Pajonk et al. also show that tea extracts reduce the release of pro-inflammatory cytokines, such as IL-1beta, IL-6, IL-8, TNFalpha and PGE2, in human white blood cells in culture, with green tea having higher anti-inflammatory properties than black tea. Both black tea and green tea inhibit one major inflammatory pathway in mouse white blood cells. Pajonk et al. add that tea's high content of polyphenols is likely to be responsible for its high anti-inflammatory activity, but that other pathways are probably involved in its clinical effectiveness.

Skin cancer, and the protective effects of catechins on the skin, have been studied extensively. Ultraviolet radiation is known to cause inflammation and immune, making the skin more susceptible to cancer. High doses of epigallocatechin gallate and other catechins are particularly effective in preventing inflammation and skin cancer, especially if delivered in the topical form. Topical epigallocatechin gallate was found to reduce the release of inflammatory prostaglandin's (the E2 series), which play a crucial role in generating free radicals and promoting tumor growth. Due to its antimutagenic and antitumor activities, green tea is a promising candidate for use in topical formulations for skin cancer prevention. Epigallocatechin gallate (EGCG) is a potent polyphenolic antioxidant extracted from green tea. Cima Labs did a study to determine the influence of several factors on the stability of EGCG in solution to obtain information that would facilitate the subsequent development of topical formulations. A second objective was to determine the stability of EGCG in various solvents in the presence and absence of different antioxidants. It was concluded that glycerin-based vehicles are suitable for stabilizing EGCG as a topical formula.

In a study done by USC/Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 10 separate experiments, mice with established chemically induced or UV light-induced skin papillomas were treated continuously with green tea in the drinking water or with i.p. injections of a green tea polyphenol fraction or (-)-epigallocatechin gallate three times a week for 4-10 weeks. Partial tumor regression or > 90% inhibition of tumor growth, as measured by changes in tumor volume per mouse, was observed in 5 experiments, and marked inhibition of tumor growth (46-89%) was observed in 5 additional experiments. Treatment of the mice with green tea or green tea constituents had an inhibitory effect on body weight increases in several but not all of the studies. Examination of the data from all ten experiments revealed that complete tumor regression occurred in 14 of 346 papilloma-bearing mice (4%) that were treated with green tea in the drinking water or with i.p. injections of green tea constituents, whereas none of the 220 papilloma-bearing control mice treated with only vehicle exhibited complete tumor regression. These observations indicate that oral administration of green tea, i.p. administration of a green tea polyphenol fraction, or i.p. administration of (-)-epigallocatechin gallate inhibited the growth and/or caused the regression of established experimentally induced skin papillomas. The main polyphenol in green tea is epigallocatechin gallate (EGCG). Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anti-cancer properties that may help prevent the onset and growth of skin tumors.