PressRelease

Hormonal therapy for treatment of breast cancer is the oldest and safest procedure for all phases of this cancer.  Clinical studies indicate that hormonal therapies are an important component of adjuvant treatments and it also tends to prevent recurrence of cancer.  Adjuvant treatments are therapies given in addition to primary therapy to increase the chance of disease free survival of postmenopausal breast cancer patients.  Two drugs that are commonly used include tamoxifen and aromatase inhibitors (AIs).  Tamoxifen's mode of action involves blocking estrogen activity in the body where as AIs prevent the body from making estrogen thereby decreasing the amount of estrogen in the tumor halting progression of tumor cells.  Tamoxifen has been used for more than twenty years and well tested in clinical trials.  Generally, further hormonal treatments are required and the drug of choice has been non-selective AIs however, there has been some concern about its toxicity.  More recently,  selective AIs have been developed that have less toxicity.  AIs come in two from:  steroidal and non-steroidal.  Clinical studies suggest that there may be clinical benefits when a non-steroidal AI is used first followed by a steroidal AI and vice versa.


The Journal of the National Cancer Institute (Aug. 22, 2011) published a report on AIs stating that toxicities associated with this drug may explain the lack o f survival improvement as compared to tamoxifen.  AIs are an alternative to tamoxifen or administered after initial therapy with tamoxifen.  The upshot is that AIs have demonstrated a decrease in breast cancer recurrence but not in improved survival.

The question here is, does aromatase inhibitors toxicity account for lack of improved survival?  A meta-analysis of 7 trials involving over 30 thousand patients was conducted at the Princess Margaret Hospital in Toronto, Ontario comparing previous clinical trials that used AIs and tamoxifen.