Adjuvant trastuzumab treatment may be beneficial for women with small human epidermal growth factor receptor 2 (HER2)-positive breast tumors, according to a review by British researchers.
Trastuzumab is the standard treatment for HER2-positive tumors larger than 1 cm, but women with smaller tumors generally do not receive adjuvant therapy because they generally have a good prognosis. In a Personal View article in the December issue of The Lancet Oncology Susana Banerjee, MD, and Ian Smith, MD, of the Royal Marsden Hospital, London, United Kingdom, point out that the prognosis may be worse for some small tumors than others, and that “there is now strong circumstantial evidence to justify some form of trastuzumab-based adjuvant therapy in most women with T1b (>0.5-≤1 cm) N0, HER2-positive breast cancers.”
The researchers reviewed data on the prognosis of small breast tumors and found that although in most cases, the prognosis for women with these tumors is excellent, some retrospective data indicate that HER2 is a marker of poor prognosis regardless of tumor size, and indirect evidence from major trials suggests that tumors <1 cm may benefit from trastuzumab treatment.
They note that present guidelines for systemic treatment of small HER2-positive tumors are uncertain and clinical practice is inconsistent. Because conducting randomized trials would be difficult, they believe the next-best approach would be a nonrandomized prospective study. They also recommend the creation of prospective databases on management of small HER2-positive tumors and the inclusion of molecular markers and multigene tests in clinical datasets to more accurately predict which treatments will benefit individual patients. On the basis of the available evidence, they recommend that healthcare providers discuss the benefits and risks of adjuvant trastuzumab with women with small HER2-positive breast cancers.