Breast cancer drug switch cuts deaths - study

ATLANTA, June 4 (Reuters) Switching to Pfizer Inc.'s drug Aromasin after a few years on another breast cancer treatment cut some women's risk of dying by 17 per cent according to a study.

Researchers looked at more than 4,700 women past menopause who had been treated for early-stage breast cancer and were disease-free after two to three years of taking the drug tamoxifen to prevent a recurrence.

About half were randomly chosen to substitute Aromasin while the other half continued on tamoxifen. Total treatment lasted five years.

Scientists tracked their progress for about 2.5 years after treatment stopped.

They found that women who switched to Aromasin had a 17 per cent lower risk of dying than others who took only tamoxifen. There were 210 deaths in the Aromasin group and 251 in the tamoxifen group.

The findings, presented at the annual meeting of the American Society of Clinical Oncology, applied to women with what is known as hormone-sensitive breast cancer. It is the latest study to compare the benefits of the two types of drugs.

''Worldwide there are still thousands of women taking tamoxifen, and you could immediately affect their chances of survival by switching to Aromasin,'' Dr. Stephen Jones, one of the study researchers and medical director for U.S. Oncology Research, said in an interview.

Tamoxifen - long the drug of choice for preventing breast cancer -- blocks estrogen, which can help fuel the growth of tumors in some cases.

Aromasin, known generically as exemestane, and similar drugs inhibit the enzyme aromatase, which is needed to produce estrogen. The aromatase inhibitors now are being used just after breast cancer surgery instead of tamoxifen in many women to keep the disease from returning. Both are taken orally.

In the new study released yesterday, side effects from the drugs differed. Women who took only tamoxifen had higher rates of blood clots, uterine cancer and vaginal bleeding. Aromasin patients had slightly more fractures.

Tamoxifen was sold by AstraZeneca Plc under the name Nolvadex but now is marketed by several generic makers.

REUTERS SY KP0846