Cancer research suggests changes in treatment maybe forthcoming

By Bloomberg News
Tuesday, April 27, 2010; HE06

The American Association for Cancer Research held its annual meeting April 17-21 in Washington. Thousands of participants were able to consider more than 6,000 papers and short talks, and several hundred longer presentations. Some highlights follow.

Matching drug with tumor

Lung cancer patients given drugs such as Tarceva and Nexavar fare better when their tumors are first tested for certain genetic traits and then matched with the corresponding treatment, a study found.

The drugs, called targeted therapies because they home in on specific biological pathways involved in tumor growth, were studied by researchers at the University of Texas M.D. Anderson Cancer Center in Houston.

Most treatment decisions now are based on cancer type, said thoracic oncologist Edward Kim, the study's lead author. That is likely to change as more studies show the benefit of tailoring treatment to the individual, said Anil Potti, an associate professor of medicine at Duke University.

"A trial like this is unprecedented," Potti said. "It shows that getting biopsies and treating patients based on those biopsies is feasible in lung cancer today. It's a huge advance in lung cancer research and in the whole concept of personalized medicine."

In the study, patients who had been treated with chemotherapy in the past underwent another biopsy. Tumor samples were tested for cancer biomarkers, including mutations to a gene called KRAS and to EGFR, or epidermal growth factor receptor, a protein that causes cancer cells to grow and divide.

Patients were placed into five marker groups. A first subset was assigned to one of four drugs without regard to their biomarkers. Patients in a second wave were assigned to drugs based on their particular tumor biomarkers, taking into consideration how people in the first group with similar biomarkers were faring.

Overall disease control -- defined as "non-progression" of the cancer -- among all participants was 46 percent after eight weeks, Kim said. However, about 71 percent of patients with mutations involving EGFR who were given Tarceva, which is designed to inhibit EGFR, had disease control at eight weeks. Among those with KRAS gene mutations, 61 percent had non-progression of their cancer when given Nexavar, Kim said.

Supplements succeed

Calcium doesn't just build strong bones; it may also fight cancer.

Researchers at the Ponce School of Medicine in Puerto Rico reported that women who took calcium had a 40 percent lower risk of getting breast cancer, while those getting multivitamins showed a 30 percent reduction.

The data contradict results of a 2008 trial that showed no reduction in cancer risk from vitamin supplements. The scientists attributed the calcium benefit seen in the study to its effect on what they called DNA repair capacity, the biological process by which cells patch up damaged DNA that otherwise may cause cancer. The report suggests women may boost their cellular defenses with dietary changes and long-term use of supplements, they said.

"Now we can monitor breast cancer risk using DNA repair capacity," said Manuel Bayona, a professor of biostatistics and epidemiology and an author of the paper.

A good analogy, Bayona said, is the management of heart disease. Just as doctors track patients' cholesterol and modify it with changes in diet or drugs, they might use blood tests to monitor the DNA repair ability of women at elevated risk for breast cancer and tweak it using dietary supplements.

The study included 744 women: 278 with breast cancer and 466 healthy controls. They were given a questionnaire that included several questions about their current and past intake of particular vitamins and minerals. The researchers also took blood samples to measure DNA repair capacity.

Monitoring breast density

Increases in breast density in a year's time may signal a higher risk of breast cancer in post-menopausal women taking estrogen and progestin, according to a study. The authors urged doctors to monitor such changes.

The study found that 20 percent of 475 women taking the hormone treatments had more than a 19 percent rise in breast density. That increase translated into 3.6 times as many cases of cancer, according to the study data.

While the study noted that breast density has long been "one of the strongest predictors of risk," this trial is among the first to show how short-term changes can affect a woman's susceptibility to the disease. "The findings suggest post-menopausal women taking hormones who experience a significant increase in breast density should reconsider their decision to take hormones," said Rowan Chlebowski, a co-author of the study. The results also indicate that "there is not enough focus on breast density in general."

Chlebowski and his co-authors worked with the Women's Health Initiative, a National Institutes of Health program focused on post-menopausal women.

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