THURSDAY, Oct. 27 (HealthDay News) — People with a specific genetic susceptibility to lung cancer may be able to trim their risk by eating vegetables from the cabbage family, new research suggests.
“We found protective effects with at least weekly consumption of cruciferous vegetables,” said Paul Brennan, lead author of a research letter that appears in the Oct. 29 issue of The Lancet. He is head of the Genetic Epidemiology Group at the International Agency for Research on Cancer in Lyon, France.
Several previous observational studies had shown that cruciferous vegetables, such as cabbage, broccoli and sprouts, protected against lung cancer. However, these studies weren’t big enough to be definitive, the authors of the new research said.
The apparent value of cruciferous vegetables lies in the fact that they are rich in isothiocyanates, which have been shown to have a chemopreventive effect against lung cancer.
But isothiocyanates are removed from the body by glutathione-S-transferase enzymes, which are produced by the genes GSTM1 and GSTT1. People who have inactive forms of these genes have higher levels of isothiocyanates.
For this study, the researchers looked at 2,141 people with lung cancer, comparing them with 2,168 healthy individuals in the Czech Republic, Hungary, Poland, Slovakia, Romania and Russia, where consumption of these vegetables has traditionally been high.
Participants filled out a food questionnaire, and also gave a blood sample so researchers could detect GSTM1 and GSTT1.
The questionnaire listed 23 foods, including three cruciferous vegetables: cabbage and a combination of Brussels sprouts with broccoli.
People with the inactive form of the GSTM1 gene who consumed cruciferous vegetables weekly had a 33 percent lower chance of developing lung cancer. People with an inactive form of the GSTT1 gene had a 37 percent lower risk, and those who had inactive forms of both genes had a 72 percent lower risk. There was no protective effect in people with active forms of the genes.
“The effect is not really all tied up with genes, although it does indicate that much of the protective vegetable effect is likely to be due to cruciferous vegetables,” Brennan said.
The American Cancer Society already recommends that people eat plenty of fruits and vegetables. Brennan noted, however, that “the evidence for any specific fruits/vegetables and cancer risk is pretty patchy.”
This study was much more specific in its findings. “By looking at population subgroups who metabolize compounds in cruciferous vegetables more slowly, and finding that they have an increased protective effect, this indicates that there is a specific protective effect against lung cancer from cruciferous vegetables,” he said.
It would be nice to have the results confirmed with randomized trials but, Brennan pointed out, “such trials are very expensive and take a long time.”
Still, Dr. Jay Brooks, chairman of hematology/oncology at the Ochsner Clinic Foundation in New Orleans, called the research a “very interesting observation.”
“We clearly know that there is a genetic susceptibility to lung cancer,” he said.
The National Cancer Institute has more on lung cancer, including the genetics of the disease.