Tea consumption is not associated with risk of prostate cancer
Slattery, M L. and West, D. W. Cancer Causes & Control Vol. 4 559-563 1993.

Data from a population-based study of newly diagnosed cases of prostate cancer (n=362) and age-matched controls (n=685) conducted in Utah (United States) between 1983 and 1986 were used to determine if cigarette smoking, alcohol, coffee, tea, caffeine, and theobromine were associated with prostate cancer risk.

These factors were examined since their use differs in the Utah population, which is comprised predominantly of members of the Church of Jesus Christ of Latter-day Saints (LDS or Mormon), from most other populations. Pack-years of cigarettes smoked, alcohol intake, and consumption of alcohol, coffee, tea and caffeine were not associated with prostate cancer risk. Compared with men with very low levels of theobromine intake, older men consuming 11 to 20 and over 20mg of theobromine per day were at increased risk of prostate cancer (odds ratio [OR] for all tumour = 2.06, 9 percent confidence interval [CI] = 1.33-. 20 and OR for aggressive tumours = 1.90, CI = 0.90-3.97, and OR = 1.74, CI 0.91-3.32, respectively).

We present biological mechanisms for a possible association between prostate cancer and theobromine. This finding needs further exploration in studies with a wider range of theobromine exposures and moree men with aggressive tumours.

How Tea may reduce the Risk of Prostate Cancer
Jain M G, Hislop G T, Howe G R, Burch J D, Ghadirian P, Int. J Cancer 1998 Dec 9, VOL: 78 (6), P: 707-11, ISSN: 0020-7136.

There are very few large-scale studies that have examined the association of prostate cancer with alcohol and other beverages. This relationship was examined in a case-control study conducted in 3 geographical areas of Canada (Metropolitan Toronto (Ontario), Montreal (Quebec), and Vancouver (British Columbia)) with 617 incident cases and 637 population controls. Complete history of beverage intake was assessed by a personal interview with reference to a 1-year period prior to diagnosis or interview. In age- and energy-adjusted models for all centers combined, the odds ratio (OR) for the highest quintile of total alcohol intake was 0.89. For alcoholic beverages separately, it was 0.68 for the highest tertile of beer, 1.12 for wine and 0.86 for liquor. The decreasing trend was significant for beer intake. The results were only significant for British Columbia out of all the 3 centers studied. Whereas coffee and cola intake was not associated with prostate cancer, a decrease in risk was observed with tea intake of more than 500 g per day (OR 0.70). Our results do not support a positive association between total alcohol, coffee and prostate cancer.

Tea and other beverage consumption and prostate cancer risk: a Canadian Study
Ellison-L-F, European journal of cancer prevention \{Eur-J-Cancer-Prev} 2000 Apr

Using participants in the 1970-1972 Nutrition Canada Survey (NCS), a retrospective cohort study was conducted to assess the relationship between tea, as well as coffee, cola and alcohol, and the risk of developing prostate cancer. The mortality and cancer experience of male NCS participants aged 50-84 years was determined up to 31 December 1993. Among the 3400 survey participants included in the study, 145 developed prostate cancer. No association was observed between tea (predominantly black tea) intake and prostate cancer. Subjects who drank more than 500 ml of tea per day experienced virtually the same risk as those who reported no tea consumption (rate ratio (RR) 1.02, 95% confidence interval (CI) 0.62-1.65). Compared to those who reported no coffee drinking, men who averaged more than 250-ml per day experienced a 40% increase in risk (95% CI 0.84-2.32). Cola consumption was not associated with an increased risk of prostate cancer. Total alcohol consumption was not related to subsequent development of prostate cancer, although very moderate consumption of wine (< 10 g per day), relative to no consumption, showed an RR of 1.48 (95% CI 1.05-2.09). These data do not support an association between consumption of tea and prostate cancer risk.

Tea and Oral Cancer

The Protective effects of tea on oral cancer
Li-N, Sun-Z, Han-C, Chen-J. Proceedings of the Society for Experimental Biology and Medicine

A double-blind intervention trial was conducted in patients with oralmucosa leukoplakia using a mixed tea product developed by the authors. Fifty nine oral mucosa leukoplakia patients, diagnosed by establishedclinical and pathological criteria, were randomly divided into a treatedgroup (3 g mixed tea oral administration and topical treatment) and a control group (placebo and glycerin treatment). After the 6-month trial, the size of oral lesion was decreased in 37.9% of the 29 treated patients and increased in 3.4%; whereas the oral lesion was decreased in10.0% of the 30 control patients and increased in 6.7%. At the sametime, the incidence of micronucleated exfoliated oral mucosa cells in the treated group (5.4 per 1000 cells) was lower than that in the control group (11.3 per 1000 cells)(P < 0.01); whereas it was 1.4 per1000 cells in 20 healthy subjects. The micronuclei and chromosomeaberration rate in the peripheral blood lymphocytes showed the same results. In pathological examination, there were significant differences (P < 0.05) in the number and total volume of the silver-stained Nuclear Organiser Regions (angora) and the proliferating index of Proliferation Cell Nuclear Antigen (PCNA) in oral mucosa cell nuclei between the treated group and the control group which indicates that cell proliferation was decreased in the treated patients. The overall results provide some direct evidence on the protective effects

Tea consumption influences risk of tongue and mouth cancer
Franceschi S, Barra S, La Vecchia C, Bidoli E, Negri E and Talamini R., Cancer Vol. 70 2227-2233 1992.

Background: The role of tobacco and alcohol consumption and the frequency of intake of a selected number of indicator foods as causes of cancer were investigated in a case-control study conducted in northern Italy.

Methods: 102 men with cancer of the tongue, 104 patients with cancer of the mouth, and 726 control subjects (the latter admitted to the hospital for acute non-neoplastic disease without respiratory illness) were interviewed Results. Similarly strong associations were observed with cigarette smoking (odds ration [OR], 10.5 and 11.8 for current smokers versus never smokers in cancer of the tongue and mouth, respectively) and alcohol (OR, 3.4 and 3.0 for > or = 60 versus < or = 19 drinks/week). The risk conferred by pipe or cigar smoking, although based on only 12 smokers who did not smoke cigarettes, seemed, however, to be lower for cancer of the tongue (OR, 3.4) than cancer of the mouth (OR, 21.9). Selected indicator foods and beverages, including green vegetables, carrots, fresh fruits, whole-grain bread and pasta, coffee and tea also affected the cancer risk similarly in the two sites. The beneficial influence of such foods and beverages seemed, however, to be more marked for cancer of the mouth than for cancer of the tongue.

Conclusions: This study suggested that, although none of the differences in the effects between cancer sites was statistically significant, tobacco from pipes and cigars and the cleansing effect of some foods of plant origin and non-alcoholic beverages may influence the risk of cancer of the tongue less strongly than the risk of cancer of the mouth.