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Fox Chase Cancer Center Study: People With MPO Gene Less Likely to Develop Lung Cancer

Research Funded by Pennsylvania's Tobacco Master Settlement

PHILADELPHIA (April 7, 2003) — A preliminary study funded with money from Pennsylvania's portion of the tobacco settlement indicates that people who have a gene called MPO may be less likely to develop lung cancer. The Fox Chase Cancer Center study was published in the Proceedings for the 2003 Annual Meeting of the American Association for Cancer Research (AACR).

There are three versions (polymorphisms) of the myeloperoxidase, or MPO gene. Scientists say about 8 percent of the population has a version of the gene called MPO A/A. Previous studies have reported that possession of at least one copy of the A version appears to have a protective effect against lung cancer, whereas the G/G form does not.

At Fox Chase, Agnes B. Baffoe-Bonnie, M.D., Ph.D., and her colleagues are comparing the frequency of polymorphisms in 10 genes in people with lung cancer and those who do not have cancer (controls). To date, two genes have been examined: XRCC1 and MPO. In an ongoing study, the researchers have collected data from 96 lung cancer patients, matching them with controls of the same age and gender.

"We didn't find a difference between the two groups concerning the presence of XRCC1 variants, but the findings regarding MPO are significant," explained Baffoe-Bonnie, an associate member in the population science division at Fox Chase.

In the control group 51.0 percent of people had at least one copy of MPO (A/-), only 37.5 percent of people with lung cancer had at least one MPO (A/-) copy. "What this tells us is that people who have one or two copies of the MPO A gene are less likely to develop lung cancer," explained Baffoe-Bonnie. "We hope to put our result in the context of other genes and environmental factors that relate to lung cancer risk."

The MPO polymorphism influences the amount of myeloperoxidase produced by cells in the lung. Everyone produces this enzyme but people with a MPO A gene produce less. MPO activates the potent carcinogen benzo(a)pyrene, which is a product of tobacco smoke, as well as the burning of most fuels and most other kinds of combustion. In the case of the MPO enzyme, less may be better.

Baffoe-Bonnie's research was funded by money received from the Commonwealth of Pennsylvania's portion of the Master Settlement Agreement of 1998 with tobacco companies.