Novartis says that its breast cancer drug Femara can significantly reduce the likelihood of the disease returning even when treatment starts several years after completing tamoxifen therapy.

The Swiss company cited an analysis of a subset of nearly 2,400 women, published in the Journal of Clinical Oncology which shows that treatment with Femara (letrozole), begun several years after completing the recommended five years of tamoxifen, reduced the risk of breast cancer returning by 63%. Also the risk of cancer spreading to other areas of the body was reduced by 61% and the median period before starting Femara was 31 months.

The Basel-based firm noted that more than 50% of breast cancer recurrences and deaths occur five or more years after completing tamoxifen treatment, adding that Femara is the only drug in the aromatase inhibitor class with data showing its potential to reduce the risk of the disease returning.

A separate analysis of results from the same trial, called MA-17 and published in the Annals of Oncology, supports the significant benefit of initiating Femara within three months of completing five years of tamoxifen, Novartis said.

The data could boost sales of Femara, which is available in more than 90 countries.