Switching to Aromasin® Improves Survival Among Postmenopausal
Women with Early Breast Cancer
Breast cancer patients who switch to Aromasin® (exemestane) after 2–3 years of Nolvadex® (tamoxifen) are less likely
to experience cancer recurrence or cancer in the opposite breast, and have better overall survival, than women who remain
on Nolvadex. These results were presented at the 2006 annual meeting of the American Society of Clinical Oncology (ASCO).
Each year, breast cancer is diagnosed in over 200,000 women in the U.S. alone. Many of these breast cancers will be hormone
receptor-positive, meaning that they are stimulated to grow by the circulating female hormones estrogen and/or progesterone.
Treatment of hormone receptor-positive breast cancer often involves hormonal therapies that suppress or block the action
of estrogen. These therapies include Nolvadex as well as a group of drugs referred to as anti-aromatase agents. Nolvadex acts
by blocking estrogen receptors, whereas anti-aromatase agents suppress the production of estrogen. Aromasin is an anti-aromatase
To assess the effect of switching to Aromasin after 2–3 years of Nolvadex, researchers conducted a clinical trial
called the Intergroup Exemestane Study. The trial enrolled 4,724 postmenopausal women with estrogen receptor-positive, early
breast cancer. After 2–3 years of Nolvadex, women were randomly assigned to continue on Nolvadex or to switch to Aromasin.
Women were treated with Nolvadex or Nolvadex followed by Aromasin for up to five years.
Women have now been followed for a median of close to five years. The following results exclude 122 patients who were found
to be estrogen receptor-negative after the start of the study.
- Compared to women who remained on Nolvadex, women who switched to Aromasin had a 25% lower risk of cancer recurrence or
development of a new cancer.
- Women who switched to Aromasin had a 17% lower risk of death compared to women who remained on Nolvadex.
- Women who switched to Aromasin were less likely to experience blood clots or gynecologic problems (such as uterine cancer),
but more likely to experience a bone fracture.
These results suggest that switching to Aromasin after 2–3 years of Nolvadex improves both overall and cancer-free
survival among among postmenopausal women with early breast cancer. Switching to Aromasin increased the risk of bone fractures
but decreased the risk of blood clots and serious gynecologic problems.
Reference: Coombes RC, Paridaens R, Jassem J et al. First Mature Analysis of the Intergroup Exemestane
Study: a Randomized Trial in Disease-free, Postmenopausal Patients with Early Breast Cancer Randomized to Continue Tamoxifen
to to Switch to Exemestane Following an Initial 2-3 Years of Adjuvant Tamoxifen. Presented at the 2006 ASCO Annual Meeting.
Aromasin® Improves Breast Cancer Outcomes Without Compromising Quality of Life (2/28/2006)
Aromasin® Approved for Early Breast Cancer (10/10/2005)