Roxanne Nelson

April 08, 2011

April 8, 2011 (Orlando, Florida) — New data suggest that eating strawberries might help prevent the onset of esophageal cancer and might be a natural alternative to chemoprevention.

The preliminary results, presented here at the American Association for Cancer Research 102nd Annual Meeting, showed that after consuming strawberries for 6 months, 29 of 36 participants with esophageal dysplastic lesions experienced a decrease in histologic grade.

"We found that 6 months of strawberry consumption can decrease histological grade of precancerous lesions," said lead author Tong Chen, MD, PhD, assistant professor, division of medical oncology, The Ohio State University, Columbus.

"We also found that freeze-dried strawberries could reduce some cancer-related molecular events, so there may be a benefit to other types of cancer as well," she told Medscape Medical News.

"The take-home message is that strawberries may be an alternative or work together with chemopreventive drugs in the prevention of esophageal cancer," she added.

Dr. Tong Chen

Although these findings are very promising, Dr. Chen cautioned that these are preliminary data and that the findings need to be replicated in large placebo-controlled randomized trials.

But strawberries are safe, readily available, inexpensive, and are a good source of a number of vitamins and minerals. "So for right now," said Dr. Chen," I would say that eating strawberries may help people at high risk for esophageal cancer protect themselves against the disease."

The important causative agents of esophageal squamous cell carcinoma are nitrosamine carcinogens, which are present in tobacco smoke, diet, and the acidic conditions of the stomach, note the authors. Among these nitrosamines is N-nitrosomethylbenzylamine (NMBA), which is present in Chinese diets.

In a preclinical study, Dr. Chen and colleagues used an NMBA-induced esophageal cancer model in rats to identify putative chemopreventive agents, including natural food products such as strawberries. They found that freeze-dried strawberries significantly inhibited tumor formation in rats by inhibiting the metabolism of NMBA and reducing the growth rate of premalignant cells.

On the basis of these earlier findings, the authors conducted a phase 1b trial in a cohort of adults with esophageal dysplastic lesions in a high-risk area for esophageal cancer. The study was conducted in China, Dr. Chen explained, because China has the highest incidence of esophageal cancer in the world.

"About 50% of esophageal cancer cases occur in China," she said.

Dysplasia Reduced and Changes at Molecular Level

A total of 36 patients completed the study; 31 patients were diagnosed with mild dysplasia (86.11%) and 5 were diagnosed with moderate dysplasia (13.89%). All participants underwent a pre- and postesophageal endoscopy and biopsy and completed the dietary strawberry diary.

For 6 months, the participants consumed 60 g of freeze-dried strawberries every day. At the end of the study period, histologic grade decreased in 26 patients with mild dysplasia (P < .0001), remained unchanged in 4 patients, and increased in 1 patient.

In patients with moderate dysplasia, histologic grade decreased in 3 patients and remained unchanged in 2 patients.

Strawberry consumption also reduced protein expression levels of inducible nitric oxide synthase (77.3% reduction; P = .03), cyclooxygenase-2 (47.3% reduction; P = .11), phospho-NFκB-p65 (63.1% reduction;= .23), and phospho-S6 (87.9% reduction; P = .02).

In addition, the authors assessed the effects of strawberries on the cell proliferation rate using Ki-67 staining. Strawberries significantly inhibited the Ki-67 labeling index by 37.9% (P = .023).

Dr. Chen pointed out that eating fresh strawberries would probably have the same effect, even though the freeze-dried powder used in the study was more concentrated (nearly 10-fold).

American Association for Cancer Research (AACR) 102nd Annual Meeting: Abstract LB-465. Presented April 6, 2011.


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