Study in male smokers continues to provide clues into the causes and prevention of multiple cancers
SEATTLE – The Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study was initiated to test the effect of vitamin supplementation on the prevention of lung and other cancers. The trial ended in 1993, but ongoing follow-up of the participants continues, offering new insights into the causes and prevention of multiple diseases, including cancer.
Results from two separate sub-studies in ATBC, presented today at the American Association for Cancer Research Third Annual International Conference on Frontiers in Cancer Prevention Research, may provide new information into the causes of prostate cancer and the prevention of stomach cancer. In the first study, a team of researchers found a link between men's height and their risk level for advanced prostate cancer. In the second study, researchers present critical evidence of the impact of fruit, vegetables, and antioxidant nutrient consumption on the risk of stomach cancer.
A Prospective Investigation of Height and Prostate Cancer Risk in Male Smokers (Abstract 223) Tall men may be at an increased risk for prostate cancer and clinically advanced forms of the disease, according to new research from U.S. and Finnish investigators.
The results showed that the tallest men experienced a 20 percent increased risk for prostate cancer, which is considered a modest increase in risk. Of the 29,000 participants in this group, some 1,346 prostate cancer cases were identified during 17.4 years of follow-up studies.
However, when this relationship was analyzed according to how far the cancer had spread, the team found a strong association between height and clinically advanced disease. In fact, the tallest men were twice as likely to get prostate cancer as the shortest men in the study group. "Our results help to clarify previous inconsistencies in the literature, and offer some insights into the etiology of prostate cancer. However, the biological mechanisms underlying this association need to be further elucidated," said Margaret Wright, Ph.D., of the Division of Cancer Epidemiology and Genetics at the National Cancer Institute, and one of the lead investigators of the study. "The possibility that height may be associated with prostate cancer risk should be studied further to evaluate whether taller men are particularly susceptible to advanced disease, but not early cancer."
A person's adult height is generally associated with their exposure to growth hormones, nutritional intake during childhood and adolescence, and heredity.
The American Cancer Society estimates that there will be approximately 231,000 new cases of prostate cancer in the United States in 2004, and about 30,000 men will die of the disease. Prostate cancer is the second leading cause of cancer death in men, exceeded only by lung cancer.
Fruits, Vegetables and Antioxidants and Risk of Gastric Cancer (Abstract 173) Several studies have suggested fruit and vegetable consumption may be protective against various diseases including several cancers. However, these results have not always been consistent.
In this study, researchers at the U.S. National Cancer Institute and National Public Health Institute of Finland assessed the association between fruit and vegetable consumption and the risk of stomach cancer in approximately 29,000 male smoker participants of the Alpha-Tocopherol, Beta Carotene (ATBC) cancer prevention study in Finland.
The stomach can be divided into two anatomic sections: the cardia (the top one inch of the stomach) and the non-cardia. Non-cardia cancer is the major form of stomach cancer in most parts of the world. Results of this study found that the effects of fruits, vegetables, and vitamins on these two types of cancer were different. Since the effect of fruit and vegetables on stomach cancer, if any, has been attributed to their vitamin content, the researchers also compared dietary intake and serum levels of several vitamins in those who did and did not develop stomach cancer among ATBC study participants.
Fruit and vitamin C consumption, but not vegetable consumption, was associated with approximately 45 percent risk reduction in non-cardia cancer. The results also suggested that lycopene, an antioxidant found in tomatoes, was associated with 34 percent reduction in risk of non-cardia cancer. With regard to cardia cancer, consumption of retinol (a form of vitamin A) was associated with a reduced risk, but alpha-tocopherol and gamma-tocopherol, two forms of vitamin E, seemed to be associated with an increased risk.
"Since our findings are similar to the results found in several other studies, fruit and vitamin C intake are likely to be useful for the prevention of stomach cancer. The effect of lycopene on gastric cancer, however, needs further studies," said Farin Kamangar, M.D., MPH, MHS, of the Cancer Prevention Studies Branch at the National Cancer Institute, and one of the lead investigators of the study.
The Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Trial was conducted by the U.S. National Cancer Institute (NCI) and the National Public Health Institute of Finland from 1985 to 1993. The purpose of the trial was to determine whether certain vitamin supplements, such as alpha-tocopherol (a form of vitamin E) and beta-carotene (a precursor of vitamin A), would prevent lung cancer and other cancers in a group of 29,133 male smokers in Finland. The participants, ages 50 to 69, provided information such as height, weight, and medical factors, as well as an extensive food frequency questionnaire.
The participants stopped taking the vitamin supplements in April 1993. However, to evaluate the long-term effects of the vitamins on cancer incidence, and overall and cause-specific mortality, the researchers acquired additional data through April 2001 (eight years beyond the end of the trial).
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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