Researchers from the Istituto Europeo di Oncologia in Milan found that women with HER2-positive node-negative breast tumours 1 cm or less in diameter have a 2.4-fold greater risk of recurrence compared to those with HER2-negative disease. Additionally, women with HER2-positive tumours that also contained receptors for progesterone and/or oestrogen had worse disease-free survival than women with hormone-receptor positive, HER2-negative tumours.

"Advances in screening have helped us to increasingly identify small, earlier stage breast tumours, but there is little clear-cut guidance on how these tumours can be treated most effectively," said lead author Giuseppe Curigliano, MD, PhD, senior deputy director of the Division of Medical Oncology at the Istituto Europeo di Oncologia. "And while there are no definitive data that support treatment with trastuzumab for patients with small, HER2-positive breast tumours that have not spread to the lymph nodes, the option should be discussed with patients."

Dr. Curigliano and his colleagues reviewed records from 2,130 women who were surgically treated at their institution between 1999 and 2006 for tumours 1 cm or less in diameter that had not spread to the lymph nodes. Of these women, 150 (7 percent) had HER2-positive disease. Researchers examined the risk of recurrence and disease-free survival among women with both HER2-positive and HER2-negative disease, and further stratified patients according to hormone receptor status (the presence or absence of receptors for oestrogen or progesterone).

After a median follow-up of 4.6 years, they found that HER2-positive disease was associated with less favorable disease-free survival, regardless of hormone receptor status. Among women with hormone receptor positive disease, 5-year disease-free survival was 92 percent for patients with HER2-positive tumours and 99 percent for patients with HER2-negative tumours. In patients with hormone receptor-negative disease, disease-free survival was 91 percent and 92 percent, respectively.

"Clinical Relevance of HER2 Overexpression/Amplification in Patients With Small tumour Size and Node-Negative Breast Cancer," Curigliano G., et. al. Istituto Europeo di Oncologia, Milan, Italy.

Source: The Journal of Clinical Oncology