Increased consumption of teas rich in catechins is associated with reduced risk of stomach, colon and other gastrointestinal cancers. However, the effects of digestion on the anticancer activity of tea catechins have largely been ignored. A study by nutrition researchers at The Ohio State University and Purdue University found that the digestive process could both alter the structure of the tea catechins and their anticancer activity.

Fabiola Gutierrez Orozco, a graduate student in the laboratory of Dr. Joshua Bomser, The Ohio State University, presented study results on April 7 at Experimental Biology 2008 in San Diego. Other co-authors of the study are Dr. Marti Cenky of Ohio State; Dr. Mario G. Ferruzzi and Rodney Green, a graduate student in the Ferruzzi laboratory, of Purdue University. The presentation at Experimental Biology is part of the scientific program of the American Society for Nutrition.

Using a model simulating gastric and small-intestinal digestion, the researchers treated gastric cancer cells and colon cancer cell lines with digested and undigested (parent) extracts of green, tea, black tea, and a combination of the most active tea catechins (EGCG/EGC). In colon cells, digestion of both the green tea extracts and the catechin combination significantly reduced anticancer activity compared to undigested parent extracts. Black tea, on the other hand, showed the same anticancer activity for both parent and digested extracts.

Digestion and the type of tea made a difference in terms of anticancer activity. In addition, the anticancer activity of the tea extracts differed between gastric and colon cancer cell lines. In gastric cancer cells, the undigested extracts were 50 percent less effective than in colon cancer cells.

What does the new study show us?

First, says Dr. Bomser, it points out that better understanding the impact of digestion on tea could lead to changes in how we formulate products in order to protect and enhance their anticancer activity. It also could change how we prepare tea now. In a study from Dr. Ferruzzi’s laboratory published last November, for example, he found that adding citrus (such as lemon juice) or ascorbic acid to green tea protected the catechins from digestive degradation. Lemon juice caused 80 percent of tea’s catechins to remain available for the body to absorb.

Second, say the researchers, some of the digestive changes may impact anti-cancer activities. Work in Dr. Ferruzzi’s laboratory has shown that digestion can alter the structure of polyphenols, degrading and destroying some while forming others. His laboratory is currently identifying these new compounds and testing their own anticancer activity.

Third, the findings of digestive impact on tea catechins are likely also true for other bioactive compounds in foods. Dr. Bomser points out that the active compound in broccoli, for example, is not released until chewing and the digestive process begins. How do we formulate food to prevent degradation and perhaps enhance anti-cancer activity?

And fourth, say the researchers, the epidemiological findings of protective impact of teas rich in the unstable, easily degraded catechins may indicate that other compounds in tea are responsible, in part, for this anticancer activity. Further research is necessary to identify these compounds and to understand the impact of digestion on their anticancer activity.

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The use of combination chemotherapy following surgery did not improve survival in patients with gastric cancer, according to a randomized clinical trial published online March 11 in the Journal of the National Cancer Institute.
The only potentially curative therapy currently available for non-metastatic gastric cancer is surgery. Recent studies have suggested that a combination of cisplatin, epirubicin, 5-fluorouracil and leucovorin (PELF) improves outcome in patients with metastatic gastric cancer.

To test the PELF combination in patients with localized disease, Francesco Di Costanzo, M.D., of the University Hospital Careggi in Florence, Italy, and colleagues in the Italian Oncology Group for Cancer Research conducted a randomized controlled trial in which 258 patients were treated with surgery or surgery followed by chemotherapy.
With a median follow-up of 72.8 months, there was no significant difference in disease-free survival or overall survival between the two trial arms. Specifically, 47.7 percent of the patients treated with chemotherapy had progressive disease compared with 51.6 percent of patients in the control arm. Overall survival was similar; at the end of the follow-up period, 47 percent of the patients in the chemotherapy were still alive compared with 45.3 percent in the surgery-only arm.
“Our study confirms that a dose-intense regimen like PELF, which showed very promising results in advanced gastric cancer, is not effective in an adjuvant setting,” the authors write. Considering the negative results in this trial and other recent adjuvant chemotherapy trials in gastric cancer, the authors write, “Adjuvant chemotherapy alone remains a controversial approach in operable gastric cancer.”
In an accompanying editorial, Aiwen Wu, M.D., and Jiafu Ji, M.D., of the Beijing Cancer Hospital and Institute in China discuss the conflicting results obtained from recent trials that tested the value of chemotherapy and radiation in localized gastric cancer.
Despite the inconsistency of the overall data, the editorialists conclude that chemotherapy, radiation, or a combination of the two should be used in patients with gastric cancer. “Surgery alone is no longer the standard treatment for patients with resectable gastric cancer, independent of the patient population or the practice location,” they write.

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