Adjuvant chemotherapy guided by a 21-gene expression assay in breast cancer

High or low recurrence scores derived from the 21-gene breast cancer assay offer strong guidance on whether chemotherapy is advisable, but the outlook is less clear for patients whose scores fall in the middle. To investigate, researchers analyzed outcomes in about 6,700 women with recurrence scores ranging from 11 to 25.

High or low recurrence scores derived from the 21-gene breast cancer assay offer strong guidance on whether chemotherapy is advisable, but the outlook is less clear for patients whose scores fall in the middle. To investigate, researchers analyzed outcomes in about 6,700 women with recurrence scores ranging from 11 to 25. Participants were randomized to receive endocrine therapy alone or in conjunction with chemotherapy. At 9-year followup, 83.3% of the patients who underwent standard endocrine remained free from invasive disease recurrence, second primary cancer, and death. That rate was noninferior to the 84.3% of chemoendocrine recipients who also had achieved invasive disease-free survival at that point. Although endocrine and chemoendocrine therapy had an overall similar effect on breast cancer patients with midrange recurrence scores, the study did suggest that chemotherapy was somewhat more beneficial in women aged 50 years or younger with scores between 16 and 25.