News in brief - Jan. 13, 2003

Targeting breast cancer treatments - Second HIV infections - Exercise and leg pain

Targeting breast cancer treatments

Findings presented at the San Antonio Breast Cancer Symposium last month are helping to zero in on the best way to target treatments.

A study of 2,005 women found a 31% decrease in death rates among those with node-positive breast cancer when doses of chemotherapy were given more frequently -- a technique called "dose dense" -- compared with conventional treatment.

"These findings are significant because all the women received the same individual and cumulative dosage of each drug -- the only difference was the interval between chemotherapy treatments -- and that one difference is shown to make a positive impact on survival," said lead author Marc L. Citron, MD, clinical professor of medicine at Albert Einstein College of Medicine and a practicing oncologist in New York.

In a separate, soon-to-begin study, oncologists at Duke Comprehensive Cancer Center in Durham, N.C., will test a new technique called gene expression to profile subtypes of each breast cancer tumor by its genetic defects, so physicians will be able to tailor treatments to a particular tumor.

The researchers believe the technique could spare millions of women from needless chemotherapy.

Second HIV infections

A report of an individual infected with a second strain of HIV despite effective drug treatment following the first infection has researchers concerned.

"For the first time, we've shown it is possible for an individual to become infected with two closely related strains of HIV," said Bruce D. Walker, MD, a researcher at Massachusetts General Hospital and Harvard Medical School in Boston.

Findings from his research, published in the Nov. 28, 2002, Nature, underscore the challenges vaccine developers face in creating a broadly effective vaccine against HIV. They also point up the importance of continuing to practice safer sex even when partners are also HIV-positive. The patient in the study admitted having an unprotected sexual encounter a couple of months before the first detection of the second virus.

Although the two viruses represented distinct strains, both were from the same group of closely related viruses.

Exercise and leg pain

A review of studies testing the benefits of exercise in people with the cramping leg pain symptomatic of peripheral arterial disease suggests that regular walking -- while painful -- is worth it.

Patients with PAD often experience pain during exercise, so they stop, said a research team led by Kerry J. Stewart, EdD, Johns Hopkins University director of clinical exercise physiology. "As a result, many are so unfit they become housebound or dependent."

PAD patients with claudication should walk until they reach a moderate level of leg pain and then continue for several minutes longer, said Dr. Stewart.

Although exercise doesn't appear to increase blood flow to the limbs, it increases muscle metabolism and endothelial function, said the researchers.

The study was published in the Dec. 12, 2002, New England Journal of Medicine.