New hormonal Rx for breast CA approved

Health,Women's Health |

Researchers are cautiously enthusiastic about anastrozole (Arimidex) a new hormonal agent that has shown a 22% increased survival rate for postmenopausal women treated for metastatic breast cancer.  Anastrozole which has just been approved by the Health Protection Branch of Health Canada has the added benefit of being a well-tolerated drug with minimal side effects.  Two identical international trials one in North America and one in Europe and Australia were conducted with more than 500 postmenopausal women unsuccessfully treated with tamoxifen and ready for second-line hormone therapy. Two-hundred and sixty-three women were randomized to receive either 1 mg/day or 10 mg/d anastrozole and 253 were randomized to receive 40 mg megestrol acetate the standard second-line hormonal therapy.   Megestrol   When the results of the two trials were combined patients on anastrozole had a median survival benefit of 4.2 months compared with patients on megestrol. The median time to death was 22.5 months on megestrol versus 26.7 and 25.5 months respectively with the anastrozole arms. At 31 months’ follow-up 170 women on the megestrol arm had died versus 151 in each of the anastrozole arms.  “Arimidex is the first single hormonal treatment for metastatic breast cancer to show a significant survival benefit in large randomized trials compared to other hormonal agents” said Dr. Jean-Marc Nabholtz senior medical oncologist at the Cross Cancer Institute in Edmonton at a news conference about the drug.   Anastrozole   The two-year survival rate was 46.3% for megestrol as opposed to 56.1% for women receiving 1 mg anastrozole and 54.6% for 10 mg anastrozole. Because the survival rate was slightly greater for patients on a lower dose of anastrozole researchers said a threshold does exist for the drug and that there is no advantage to giving a higher dose than 1 mg.  Asked to comment on the drug Dr. Hulbert Silver professor of medicine at the University of British Columbia cautioned a similar study done at the University Women’s Hospital in Hamburg Germany did not report comparable survival benefits. The findings published in the European Journal of Cancer (March 1996) showed that there were no significant differences between anastrozole and megestrol in terms of response rate or time to progression of the disease.  Nevertheless according to Dr. Silver “just the reduction of side effects would make it a promising drug.”moonlakerxAnastrozole is an aromatase inhibitor and works by stopping this enzyme from producing estrogen in the cells of various tissues such as liver and muscle. According to Dr. Nabholtz “Arimidex is the most powerful inhibitor of aromatase we know of in practice right now.”   Mild nausea   Along with the trend to prolonging survival anastrozole produces relatively few and minor side effects. Dr. Kathleen Pritchard head of oncology at Toronto-Sunnybrook Regional Cancer Centre said these may include gastrointestinal upsets very mild nausea or diarrhea.  Anastrozole is not associated with the significant ongoing weight gain routinely reported by patients receiving megestrol said Dr. Pritchard. Megestrol a progestational mimics the effects of early pregnancy. Additionally patients on megestrol were more at risk for such life-threatening complications as phlebitis and blood clots.  “With Arimidex there are no symptoms of menopause that we’ve seen with tamoxifen in the past” said Dr. Pritchard.  The combined analysis further revealed the incidence and severity of hypertension shortness of breath vaginal hemorrhage and sweating was a lot less for those in the anastrozole arm of the trial.  While tumor shrinkage was similar with either drug patients are able to tolerate the aromatase inhibitor longer and may derive more benefits.  Asked to comment Dr. Maureen Trudeau a medical oncologist at the Women’s College Hospital said “The Arimidex I like because it’s so well tolerated. But I think there’s a role for both drugs.”  Dr. Turner said she prescribes megestrol for women who want to gain weight or who are depressed since it can help improve the patient’s mood.  Anastrozole’s greatest potential may result from earlier intervention with the drug said Dr. Nabholtz. Currently an international study is getting under way randomizing over 6000 patients to assess anastrozole’s efficacy as adjuvant therapy. ATAC (Arimidex Tamoxifen Alone or in Combination) will determine if anastrozole will be even more beneficial as first-line hormone therapy or as preventive therapy. Twenty-five centres in Canada are involved.  Anastrozole has been included in guidelines for second-line treatment for three months now.  Dr. Nabholtz said “We are not staying static. If it’s working in second line it should wo