New four-year data confirm that initial treatment with Femara (letrozole) following breast cancer surgery provides significantly greater protection from the recurrence and spread of cancer to distant parts of the body than tamoxifen.

Longer-term data comparing two arms of the independent breast international group (BIG) 1-98 trial were presented at the European Society of Medical Oncology congress in Istanbul, Turkey, by Dr Alan Coates, MD, Clinical Professor in the School of Public Health at the University of Sydney in Australia.

After a median follow-up of more than four years (51 months), postmenopausal women with hormone-sensitive early breast cancer taking Femara had an 18 per cent reduction in their overall risk of breast cancer recurrence and a 19per cent reduction in the risk of their cancer spreading to another part of the body. Cancer that spreads to other parts of the body increases the likelihood that a woman will die from the disease.

Importantly, the use of Femara resulted in greater disease-free survival in two groups of women who are at particular risk of recurrence those whose cancer had already spread to the lymph nodes at the time of diagnosis (node positive) and those who had received chemotherapy. In these groups, the risk of recurrence was reduced in the study by 23 per cent (p=0.004) and 26 per cent (p=0.03), respectively.

"It is great news to see that in patients with more than four years of median follow-up from this important trial, the results clearly confirm earlier findings that letrozole offers these women an effective hormonal therapy to lower the risk of breast cancer returning or spreading after surgery," said Prof Beat Thürlimann of St Gallen, Switzerland, and the BIG 1-98 Trial study chair. "The data also confirm a consistent safety profile, with no increase in adverse events in patients with longer-term treatment."

For the first time, results from BIG 1-98 also revealed emerging evidence that Femara may benefit women with node negative disease (i e. those whose cancer is not detected in the lymph nodes at diagnosis). In this group at 51-month median follow-up, Femara reduced the risk of breast cancer coming back by 12 per cent compared to 2 per cent observed at the 26-month median follow-up, although this measure did not reach statistical significance.

The current analysis included nearly 5,000 women assigned to receive five years of continuous Femara or tamoxifen. The primary core analysis conducted after a 26-month median follow-up included women assigned to two other arms of the study, where they received Femara or tamoxifen for two years followed by three years of the other agent.

"Longer follow-up data out to more than four years in 5,000 women provide the most compelling evidence to date that Femara helps to protect against breast cancer relapse in postmenopausal women," said Diane Young, vice president and Global Head of Clinical Development at Novartis Oncology. "We are committed to ongoing research that will help define optimal treatment for women with breast cancer."

Femara is the only medicine in its class indicated for women with hormone-dependent breast cancer taken as either initial treatment immediately after surgery or after they have completed five years of tamoxifen therapy (extended adjuvant setting).

Adverse events for both Femara and tamoxifen were consistent with previously reported results from this trial, as well as current Femara prescribing information for adjuvant treatment. The most common side effects experienced by patients taking Femara in the trial were hot flushes, fatigue, joint pain and nausea.

BIG 1-98 is the only clinical trial that incorporates both a head-to-head comparison and a sequencing of Femara and tamoxifen as adjuvant treatment for postmenopausal women with hormone receptor-positive breast cancer. The results of the primary core analysis of the head-to-head comparison based on a median follow up of 26 months were published in the New England Journal of Medicine on December 29, 2005. The BIG 1-98 trial was conducted by the International Breast Cancer Study Group (IBCSG) with many independent centres and was supported by Novartis.