Certain compounds found in cruciferous vegetables—broccoli, cauliflower, watercress, and the like—may be the key to slowing the advancement of lung cancer, says a group of studies from Georgetown University.1,2
The benefits of these compounds were seen in two studies whose findings were published in the journal Cancer Research last month.
Inhibiting Cancer Growth
The first study1 tested the effectiveness of the compounds in a group of mice in which lung cancer had been induced. The second research project2 involved testing the compounds on a group of human lung cancer cells. The results imply that the compounds could be used in treatment design for current and former smokers as a way to ward off the development of lung cancer, the researchers stated.
"These studies provide significant insight into the mechanisms of lung cancer prevention, and suggest ways the process can be slowed down after exposure has already occurred," explained Fung-Lung Chung, PhD, the study's chief investigator and a professor of Oncology in the Lombardi Cancer Center at Georgetown. "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."
A Co-Existing Lung Pathology
Lung cancer is not always found in people with pulmonary hypertension (PH). Yet it can occur in a type of lung disease in which PH occurs secondarily known as pulmonary fibrosis.3,4
Symptoms of lung cancer include persistent, progressive cough; constant chest pain; coughing up blood; shortness of breath, wheezing, or hoarseness; repeated bouts of pneumonia or bronchitis; neck or face swelling; loss of appetite or weight loss; and fatigue.
Treatment includes surgery to remove the cancer, chemotherapy, radiation therapy, and a type of laser therapy known as photodynamic therapy (PDT)—the use of a special chemical injected into the blood stream and absorbed throughout the body.5
Smoking is, by far, the most significant risk factor for the disease, but exposure to asbestos, radon, and certain cancer-causing agents in the workplace like radioactive ores or inhaled chemicals, is also a possible cause.6
Measuring Cancer Advancement
The aim of this research was to determine whether these vegetable-derived compounds, made from naturally occurring isothiocyanates (eye-soh-thy-oh-SYE-uh-nates) could reduce the progression of lung cancer, both in a lab experiment, and in mice.
First, the research team induced lung cancer in a group of mice by exposing the animals to a group of tobacco-based carcinogens (cancer-causing elements). One group of mice received the compounds through their diet, and a second group did not so that the investigators could compare the results.
More than ten months later, lung tissue from each mouse was examined. The incidence of lung cancer was about half that of those not fed the compounds, the researchers reported. In those mice in which the compounds reduced lung cancer incidence, the researchers noted that a form of cancer cell suicide known as apoptosis (ap-ahp-TOE-sis) had occurred.
More Positive Results
The second study examined the effect of these compounds on human lung cancer cells. A special gene was inserted into the cells to help them grow quickly, simulating what would happen in cancer development.
Results showed that a derivative of isothiocyanate pushed the cells to undergo apoptosis, compared to cells that did not have the gene inserted, suggesting that the vegetable compounds may halt the rapid growth of lung cells "from the outset".
The studies were the continuation of more than two decades of research by Chung and his colleagues. Earlier, the research team identified the vegetable-based compounds that may be beneficial in this regard. He and his team also showed that the compounds may be able to hinder the development of lung cancer cells.7
"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," Chung said.
1. Conaway CC, Wang CX, Pittman B et al. Phenethyl isothiocyanate and sulforaphane and their N-acetylcysteine conjugates inhibit malignant progression of lung adenomas induced by tobacco carcinogens in A/J mice. Cancer Res 2005 Sep 15;65(18):8548-57.
2. Yang YM, Jhanwar-Uniyal M, Schwartz J et al. N-acetylcysteine conjugate of phenethyl isothiocyanate enhances apoptosis in growth-stimulated human lung cells. Cancer Res 2005 Sep 15;65(18):8538-47.
3. Yoshimura A, Kudoh S. Idiopathic pulmonary fibrosis and lung cancer [Translated from Japanese]. Gan To Kagaku Ryoho 2003 Feb;30(2):215-22.
4. Ma Y, Seneviratne CK, Koss M. Idiopathic pulmonary fibrosis and malignancy. Curr Opin Pulm Med 2001 Sep;7(5):278-82.
5. National Cancer Institute. National Institutes of Health (NIH). What You Need to Know About Lung Cancer. Available at: http://www.cancer.gov/cancertopics/wyntk/lung/page1. Accessed October 17, 2005.
6. American Cancer Society. What Are the Risk Factors for Lung Cancer? Available at: http://www.cancer.org/docroot/CRI/content/CRI_2_4_2X_
What_are_the_risk_factors_for_lung_cancer_26.asp?rnav=cri. Accessed October 17, 2005.
7. Nishikawa A, Furukawa F, Ikezaki S et al. Chemopreventive effects of 3-phenylpropyl isothiocyanate on hamster lung tumorigenesis initiated with N-nitrosobis(2-oxopropyl)amine. Jpn J Cancer Res 1996 Feb;87(2):122-6.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
