Sept. 15, 2005 -- New research shows that a family of compounds found in broccoli and other cruciferous vegetables -- like cauliflower and watercress -- may stop the spread of lung cancer and lead to new treatments for the deadly disease.
Diets rich in fiber and vegetables have been associated with a reduced risk of cancer. This year more than 1.4 million Americans will be diagnosed with cancer and more than 500,000 Americans will die of cancer, according to the CDC. An estimated 32% of these deaths may be related to diet.
In addition, human lung cancer cells treated with the compounds died off at a faster rate than untreated cells, which may lead to a slower progression of existing disease.
Researchers say it's the first study to suggest that treatment with isothiocyanates can slow the progression of lung cancer as well as reduce the risk of tumors in people already exposed to cancer-causing substances, such as tobacco smoke.
The new U.S. Department of Agriculture guidelines say Americans should eat five to nine servings of fruits and vegetables daily. The CDC and the National Cancer Institute also say that eating more fruits and vegetables, as part of a diet low in saturated fat and high in fiber, may reduce the risk of getting cancer and other chronic diseases.
Lung cancer is the leading cause of cancer death among American adults, and the disease is considered virtually unbeatable once a tumor develops.
In two related studies, published in the journal Cancer Research, researchers looked at the effects of isothiocyanates on both lung cancer prevention and treatment.
Veggies May Prevent Lung Cancer
In the first study, researchers exposed mice to lung cancer-causing substances (carcinogens) in tobacco. Later, one group of mice was fed the vegetable compounds. After examining the lungs of all the mice the researchers found that mice fed the broccoli ingredient were less likely to develop lung tumors than the untreated mice.
But researchers say it's still too early to say if eating cruciferous vegetables can provide enough of the compounds to provide protection against cancer.
"Because the amount of carcinogens we used to induce tumors was very high, we needed to use a very high dose of isothiocyanates to see any effect," says researcher Fung-Lung Chung, PhD, professor of oncology at Georgetown University Medical Center, in a news release.
The results of the study provide a basis for future evaluation of the potential of these compounds as chemo-preventive agents in smokers and ex-smokers with early lung lesion, they write.
A Veggie Pill to Treat Cancer?
In the second study, researchers looked at the effect of treatment with the vegetable compounds on human lung cancer cells in the lab.
The results showed that the treatment caused the rapidly growing cancer cells to die off at a faster rate than untreated cells. They also say the findings that cancer cells are more sensitive to the cell-death-promoting effects of the compounds suggest that the compounds work selectively on cancer cells.
Researchers say if future studies confirm these results these chemicals may be put into a veggie pill of sorts that may one day treat or help prevent lung cancer in people at risk, such as smokers.
"These studies provide significant insight into the mechanisms of lung cancer prevention and suggests ways the process can be slowed down after exposure has already occurred," says Chung. "We still need to do more research, but it may be that an agent containing these ingredients could, to some degree, help protect people who have developed early lung lesions due to smoking."
"In any case, we know that eating vegetables is generally good for us and that some studies have shown they help lower a person's risk of developing cancer," says Chung.