LE Magazine June 2003
Fish and marine fatty acid
consumption causes lower
risk of metastasis
Good news on the battle against prostate cancer has recently surfaced in Sweden where researchers have reported that both fish and marine fatty acids can reduce the risk of cancer metastasis.
"Experimental studies suggest that marine fatty acids have an anti-tumor effect on prostate tumor cells," stated the researchers in Cancer Epidemiology Biomarkers & Prevention. "The aim of this study was to investigate whether high consumption of fish and marine fatty acids reduces the risk of prostate cancer in humans."
In their study, the dietary intake of 47,882 men was assessed in 1986, 1990 and 1994 via a validated food frequency questionnaire. During 12 years of follow-up, 2,482 cases of prostate cancer were diagnosed of which 617 were diagnosed as advanced prostate cancer, including 278 metastatic cancers. The results showed that
eating fish more than three times per week was associated with a reduced risk of prostate cancer with the strongest association linked to metastatic cancer. Furthermore, the intake specifically of marine fatty acids from foods showed a similar but weaker association. Each additional daily intake of 500 mg of marine fatty acid from food was associated with a 24% decreased risk of metastatic cancer [Cancer Epidemiol Biomarkers Prev, 2003;12(1):64-67].
"We found that men with high consumption of fish had a lower risk of prostate cancer, especially for metastatic cancer," concluded researcher K. Augustsson. "Marine fatty acids may account for part of the effect, but other factors in fish may also play a role."
Anti-radiation pills for children
The threat of a terroristic nuclear retaliation has prompted the American Academy of Pediatrics to urge all households, schools and child-care centers near nuclear power plants to keep potassium iodide pills on hand to protect children from thyroid cancer in the event of a release of radiation.
Dr. Sophie J. Balk, a New York pediatrician who leads the committee that wrote the policy said that this decision was based on the growing concern about both terrorism and the war in Iraq. "Children are especially vulnerable to the effects of radiation, in part because they are closer to the ground, where fallout settles and because their bodies absorb and metabolize substances differently," said representatives from the pediatrics academy.
A simple tablet, potassium iodide protects the thyroid gland from damage due to radioactive iodine - one of the most common isotopes released in a nuclear explosion. The thyroid gland is particularly susceptible to this form of radiation because it is designed to concentrate this mineral for normal dietary use. However, the thyroid cannot distinguish between normal iodine and its lethal radioactive form.
"In the human body, radioactive iodine travels to the thyroid like stable iodine," state researchers at Harvard University. "Potassium iodide pills flood the thyroid with the stable version, lowering the uptake of the radioactive atoms, which are subsequently excreted in urine."
For more information about this new policy visit the academy's web site at www.aap.org. It is also scheduled to appear in the June issue of their journal, Pediatrics.
Aspirin users show lower
esophageal cancer risk
People who suffer from acid reflux may want to consider taking aspirin or related non-steroidal anti-inflammatory drugs (NSAIDs) to help ward off esophageal cancer, say researchers at the University of California, San Francisco.
According to their review published in the January issue of Gastroenterology, the results from nine previous studies showed that people who used aspirin or other NSAIDs had roughly a 40% lower annual risk of esophageal cancer, a relatively rare but often fatal disease. In addition, these studies have also found that more frequent use was associated with greater protection than intermittent use and that when broken down by medication type, aspirin showed the strongest positive effect. Other NSAIDs such as ibuprofen were found to be only "borderline protective."
While at first glance the association between NSAIDs use and a lower risk of esophageal cancer seems odd - one of the medications' best-known side effects is irritation of the gastrointestinal tract - researchers contend that these results may prove that NSAIDs can help prevent cancer development in people at increased risk, such as those with Barrett's syndrome.
Barrett's syndrome is a change in the lining of the esophagus caused by acid reflux. A small percentage of people with this syndrome develop esophageal cancer due to the cumulative damage induced by the acid.
"Several years ago, I would have doubted the association found in the new study," said Dr. Michael J. Thun of the American Cancer Society. "However, laboratory research in recent years has given a strong biological basis to the idea that NSAIDs use might lower the risk of some cancers, including those of the colon and prostate."
The reason for NSAIDs' potential benefit has to do with its ability to fight inflammation, which is thought to play an important role in the complex cancer process. Specifically, NSAIDs block the activity of an enzyme called COX-2, which is suspected in aiding cancer-cell growth. Studies have shown that COX-2 activity is induced in the early development of some tumors, including those of the esophagus.
However, NSAIDs such as aspirin, ibuprofen and naproxen have also been found to block the COX-1 enzyme, a feature that means they can also irritate the gastrointestinal tract. This means that these new findings could, in part, reflect the fact that people with acid reflux often avoid NSAIDs. If such is the case, these results would create a false impression that NSAIDs were helping to prevent cancer. This "reverse causation" is a possibility, noted Dr. Thun.
"What's missing is the final proof that NSAID use directly lowers esophageal cancer risk," he said. "Because regular NSAIDs use can cause GI problems, doctors need a high degree of certainty that the drugs can safely lower cancer risk before they recommend them for that purpose. Among the major questions that future studies must answer are what NSAIDs dose and what duration of use might do the job."
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