The University of Albany has connected the pregnancy protein alpha-fetoprotein (AFP) to breast cancer slowing down in rats exposed to pregnancy hormones such as estrogen, progesterone, or human chorionic gonadotropin.

These pregnancy hormones were shown by the authors to induce AFP during the term of pregnancy.

The hormones also appear to inhibit breast cancer growth in previous rat studies, although estrogen and progesterone fuel the growth of breast cancer in humans.

Herbert Jacobson, PhD, who has been studying AFP in rats for over twenty years, believes the protein is the cause of the pregnancy-related reduction in breast cancer risk.

“Twenty-five years ago I deduced that this must be the agent responsible for lowering breast cancer risk in women who have been pregnant,” he tells WebMD. “And the research we have done since then supports this hypothesis.”

Pregnancy, particularly before the 30 years old, lowers a woman’s lifetime risk of developing breast cancer. Also having more than one child is preventative.

Alpha-fetoprotein is produced by the fetus, and size of the protein during pregnancy can help to screen out possible birth defects.

Extremely high AFP levels portend the appearance of neural tube defects or an abdominal wall defect known as omphalocele, and extremely low levels suggest Down syndrome.

The protein is usually not detected in the blood of healthy men and women who are not yet pregnant. In these groups, elevated AFP levels suggest the presence of some cancers.

In their new study, in the December issue of Cancer Prevention Research, Jacobson and associates treated cancer-exposed rats that were not pregnant with estrogen, estrogen plus progesterone, or human chorionic gonadotropin (HCG).

As in previous studies, all of these treatments are associated with reduced levels of breast cancers in the high-risk rats.

Each of the hormone treatments were also connected with elevated AFP levels and AFP was found to slow down the growth of breast cancer cells in lab cultures.

“Hormones in pregnancy, such as estrogen, all induce AFP, which directly inhibits the growth of breast cancer,” Jacobson says in a news release.
Second Opinion

However, devil’s advocate and cancer specialist Powel Brown, MD, PhD, says the research does not show that this is true beyond a shadow of a doubt.

As is the case with these kinds of studies, says Sandy Hutchens Cancer Prevention, there will be those that promote the idea and there will be detractors. We await the results of further studies and even possibly some proof on this unique view into breast cancer prevention.

Pregnant and Facing Breast Cancer

The research released Wednesday is the first to show Iressa can be more effective than chemotherapy as a first-line treatment, and some experts are hopeful it will prompt the Food and Drug Administration to allow wide use of the drug, made by AstraZeneca PLC. Others are skeptical. Though the study shows an effect on cancer growth over one year, the drug’s impact on long-term survival is still in question. Also, the study was done in Asia, and the drug seems to work best with specific patients — Asians, women and nonsmokers who carry a specific gene mutation.

“I’d venture to say that additional studies will be requested in the United States population,” said Dr. Len Lichtenfeld, the American Cancer Society’s deputy chief medical officer.

AstraZeneca, which funded the study, is not planning a new push for expanded FDA approval of the drug, a company spokeswoman said. But the company is continuing to share data about the drug with federal health officials, she added.

Iressa is a daily pill that more precisely targets cancer rather than healthy cells. It’s an attractive alternative to standard chemotherapy, which involves trips to a hospital or clinic for infusions of poisonous chemicals that cause nausea and hair loss. In 2003, the FDA approved Iressa as a last-resort treatment for patients with the most common form of lung cancer, called non-small-cell lung cancer. The market was significant: Lung cancer kills more Americans than any other kind of tumor, and the Cancer Society estimates it will cause nearly 160,000 U.S. deaths this year. Non-small-cell lung cancer represents 85 percent of lung cancer cases.

But in 2005, the FDA stopped allowing new patients to go on Iressa after early results from a federally sponsored study failed to show it improved lung cancer patients’ survival rates. Another lung cancer pill, Roche Group’s Tarceva, acts in a way similar to Iressa and remained on the market as a treatment for patients not helped by chemotherapy. There wasn’t widespread outcry at the loss of Iressa because Tarceva remained available, said Dr. Edward Kim, a lung cancer specialist at the University of Texas M.D. Anderson Cancer Center.

Interest in Iressa continued, though, as doctors have become increasingly interested in personalized approaches to cancer treatment. Studies have shown some drugs work better in certain breast and colon cancer patients than others, and earlier studies have found that Iressa dramatically shrunk tumors in patients who had lung cancers with a specific genetic mutation. That kind of scenario is observed in only a small fraction of U.S. lung cancer patients, but is much more common in Asia, scientists say.

The latest study was led by Dr. Tony Mok of the Chinese University of Hong Kong, and involved about 1,200 patients throughout southeast Asia. The study group included the kind of people most likely to have the mutation, said Dr. Pasi Janne, a Dana-Farber Cancer Institute lung cancer specialist.

The study measured cancer growth within a year after treatment, comparing patients who got Iressa to others who got chemotherapy. After one year, 25 percent on Iressa were alive without their cancer getting worse, as compared to 7 percent of those on chemo. Results were even better in those with the mutation. In those without the mutation, chemotherapy was more effective. The study was published online Wednesday by the New England Journal of Medicine. A second study released by the journal concluded that large-scale screening of lung cancer patients for the genetic mutation is feasible and can lead to wiser treatment.

Cancer Facts : How Does Lung Cancer Develop? embedded by Sandy Hutchens

Lung cancer develops when smoking, air pollutants and free radical formation damages sensitive lung tissue, causing the cellular DNA to restructure and malfunction. Avoid lung cancer by quitting smoking with information from a doctor in this free video on cancer.

Expert: Dr. David Cathcart
Bio: Dr. David Cathcart specializes in occupational medicine and has an in-depth knowledge of cancer, as well as experience dealing with cancer patients and treatment for multiple years.