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Scientific studies related to EGCG(3)
Reports from several ongoing clinical studies on the cancer chemopreventive potential of EGCG and green tea products have begun to emerge. Spurred by previous results that indicated EGCG could inhibit cervical cancer cell growth in vitro through the regulation of gene expression, cell cycle progression, and apoptosis (Ahn et al., 2003a), Ahn and coworkers (2003b) investigated the clinical efficacy of various EGCG and green tea preparations on human cervical lesions. A total of ninety women with human papilloma virus (HPV) infected cervical lesions were divided into four treatment groups and one control group. Patients in the treatment groups each received one of the following regimens: 1) a local application two times per week of an ointment formulated from the great tea extract preparation polyphenon E for 12 weeks; 2) a 200 mg daily oral dose of polyphenon E for 8-12 weeks; 3) both local and oral polyphenon E for 12 weeks; and 4) a 200 mg daily oral dose of EGCG for 8-12 weeks.
The cervical lesions were evaluated before, during and after treatment by Pap smear cytology and other procedures that included a DNA-RNA hybrid capture method for HPV DNA detection. Positive responses included an overall decrease in the severity of lesions, loss of HPV DNA in the cervical lesions that were previously tested positive, and a complete loss of cervical lesions confirmed by tissue biopsy. Overall, 35 out of the 51 patients treated with either EGCG or green tea extract preparations showed a clinically significant positive response. The greatest number of patients responded positively to the topical polyphenon E, with or without supplemental oral polyphenon E (75% response). Over half of the patients that received either oral polyphenol E alone or purified EGCG also showed a significant response. Few side effects were observed in the patients treated with either EGCG or other green tea products. In contrast, only 4 out of the 39 untreated control group showed a positive clinical response. While a small number of the patients in the untreated group had some degree of improvement, a significantly larger portion of these patients showed no improvement or progressed to more advanced stage disease.