Esophageal cancer is the sixth most frequent cause of cancer death in the world, and the third most common kind of gastrointestinal cancer.
According to the American Cancer Society, more than 16,000 new cases of esophageal cancer will be diagnosed in the United States this year.
Last year, researchers from Ohio State University (OSU) reported that raspberries, strawberries, blueberries, Brazilian açaí berries, and Chinese goji berries inhibited the growth of esophageal tumors in rats, equally well (Stoner GD et al. 2010).
Now, results from a clinical trial led by OSU researchers and colleagues in China suggest that strawberries may help people at risk of esophageal cancer decrease that danger.
Lead author Dr. Tong Chen of OSU presented the findings on April 6 at the American Association for Cancer Research (AACR) 102nd meeting 2011 in Orlando, Florida.
As she said, “We concluded from this study that six months of strawberry treatment is safe and easy to consume. In addition, our preliminary data suggests that strawberries decreased histological grade of precancerous lesions and reduced cancer-related molecular events.” (OSU 2011)
Based on the 2010 results in rats, the researchers embarked on a clinical trial in China to investigate the effects of freeze-dried strawberries on patients with precancerous esophageal lesions.
(Most patients with precancerous lesions in their esophagus will develop esophageal cancer.)
“We found that daily consumption of strawberries suppressed various biomarkers involved in esophageal carcinogenesis, including cell proliferation (uncontrolled cell growth), inflammation and [pro-cancer] gene transcription,” Chen said. (OSU 2011)
Each of 36 study participants ate 60 grams (about two ounces) of freeze-dried strawberries daily for six months.
The researchers biopsied tissue samples from participants' esophaguses, before and after the strawberry consumption.
Encouragingly, 29 out of 36 participants showed a decrease in “histological grade” of the precancerous lesions during the study.
(Histological grading is a measure of the progress of a tumor, and is used to estimate a patient's prognosis and plan their treatment.)
As Dr. Chen said, “Our study is important because it shows that strawberries may slow the progression of precancerous lesion in the esophagus. Strawberries may be an alternative, or may work together with other chemopreventive drugs, for the prevention of esophageal cancer. But, we will need to test this in randomized placebo-controlled trials in the future.” (OSU 2011)
Chen and her team are studying esophageal squamous cell carcinoma, which makes up 95 percent of cases of esophageal cancer worldwide. The survival rate is very low, with only 10 percent of patients living 5 years after diagnosis.
In the United States, Canada, and Europe, the risk factors for developing esophageal cancer include tobacco and alcohol use, along with diets lacking in fruits and vegetables.
In Asia, additional risk factors include dietary intake of salty food and food contaminated with various mycotoxins; deficiencies in dietary vitamins and minerals; and throat injuries from hot beverages.
The study received funding from the California Strawberry Commission.
Ohio State University (OSU). Strawberries May Slow Precancerous Growth in Esophagus. April 6, 2011. Accessed at http://medicalcenter.osu.edu/mediaroom/Pages/release.aspx?newsID=6491
Stoner GD, Wang LS, Seguin C, Rocha C, Stoner K, Chiu S, Kinghorn AD. Multiple berry types prevent N-nitrosomethylbenzylamine-induced esophageal cancer in rats. Pharm Res. 2010 Jun;27(6):1138-45. Epub 2010 Mar 16. Erratum in: Pharm Res. 2010 Sep;27(9):2031.
Stoner GD, Chen T, Kresty LA, Aziz RM, Reinemann T, Nines R. Protection against esophageal cancer in rodents with lyophilized berries: potential mechanisms. Nutr Cancer. 2006;54(1):33-46.