A new role for Femara in the treatment of advanced breast cancer

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Despite a dramatic rise in the incidence of breast cancer in North America and Europe, the death rate from this disease has been falling in the last few years. Nevertheless, breast cancer remains a leading cause of death and loss of years of life among women. The Canadian Cancer Society estimates for this year 19,500 women will develop breast cancer in Canada, and that 5,500 women will die from the disease.

Yet even in light of such statistics, there continue to be advances in treatment options that give patients and their physicians new approaches to fighting this disease.

One such advance is Health Canada’s recent approval of Femara (letrozole) as first-line treatment for advanced breast cancer in postmenopausal women. For decades tamoxifen, an estrogen agonist, has been the gold standard for first-line treatment of advanced breast cancer. Now, based on data from the largest study ever to evaluate a hormone therapy in advanced breast cancer, Femara, an aromatase inhibitor, has been shown to be significantly more effective than tamoxifen. This approval may profoundly change the treatment paradigm for advanced breast cancer patients simply because it offers a new option for first-line therapy.

The study on which Health Canada based its approval was a head-to-head comparison of the effectiveness of Femara versus tamoxifen as first-line treatment in postmenopausal women with advanced breast cancer. The study was a randomized, double blind multi-centre trial involving more than 900 women around the world. The women in this trial had locally advanced (stage IIIB) disease, metastatic breast cancer (stage IV), or recurrences which were not amenable to surgery or radiotherapy, and positive or unknown estrogen receptor in their cancers.

The results of this trial show that after 32 months of follow-up, response rates (a sustained reduction in the size of the tumors) was significantly greater in patients taking Femara than in those taking tamoxifen. Patients taking Femara were able to delay the progression of their disease for 9.4 months compared to 6.0 months for patients taking tamoxifen.

As well, the study indicated significant differences between Femara and tamoxifen with respect to overall tumour response rates (32 per cent vs. 21 per cent) rate of clinical benefit (50 per cent vs. 38 per cent).

In a supporting study involving 324 postmenopausal women with primary, or untreated, breast cancer, Femara was compared against tamoxifen as a pre-operative therapy. Patients in the study were given either Femara or tamoxifen for four months prior to surgery. Results of the study showed that regardless of tumour size, significantly more patients obtained a complete response or partial response with Femara than with tamoxifen, and as a result, more women on Femara were able to undergo breast-conserving surgery compared to tamoxifen (45 per cent vs. 35 per cent).

Femara is a once-a-day oral treatment. It was first approved in 1997 as a second-line therapy following disease progression after tamoxifen. With Femara now indicated for first-line treatment, with an improved survival rate, physicians and their patients have a more effective option for the treatment of advanced breast cancer.