Assay helps gauge long-term risk of breast Ca return: slated for marketing early this year: test may enable doctors to reserve chemo for patients with a high risk of recurrence.(News)

SAN ANTONIO -- The ability to predict long-term likelihood of breast cancer recurrence in node-negative patients is markedly enhanced by the use of a novel multigene assay, Dr. Soonmyung Paik declared at a breast cancer symposium sponsored by the Cancer Therapy and Research Center.

The assay performed favorably in a large-scale, prospective, multicenter validation study, reliably separating patients into groups at low and high 10-year risk of distant disease recurrence.

Such information should enable physicians to reserve chemotherapy for higher-risk patients in whom it is most likely to be beneficial, said Dr. Paik, director of pathology at the National Surgical Adjuvant Breast and Bowel Project (NSABP) in Pittsburgh.

He called the 21-gene, real-time reverse transcription-polymerase chain reaction assay, developed by Genomic Health Inc., "a major advance" because of its demonstrably greater prognostic power compared with the rather limited standard indicators--tumor size, grade, and patient age--in use for many decades.

Indeed, in a multivariate analysis, only the assay-based recurrence score retained significance as a predictor.

Equally important is the fact that the assay uses thin tissue specimens embedded in paraffin, a preservation method available to all breast cancer patients. In contrast, while gene microarray methods show great promise in predicting cancer outcome, at present they require special tissue handling impractical in routine practice, Dr. Paik explained.

The development of tools to aid in individualizing clinical decision making regarding adjunctive therapy in women with early breast cancer is a high priority. Randomized trials conducted by NSABP and others have dearly shown that long-term outcome in patients with node-negative, estrogen receptor-positive breast cancer is better with chemotherapy plus 5 years of tamoxifen than with tamoxifen alone. But chemotherapy is onerous, and it's important to be able to identify subgroups of low-risk women who can safely avoid it.