Predictors of effectiveness of the use of steroidal aromatase inhibitors after progression on non-steroidal aromatase inhibitors in advanced breast cancer patients Background: Clinical evidence suggests that steroid aromatase inhibitors (SAI) lack cross resistance with non-steroid aromatase inhibitors (nSAI). Therefore, the use of SAI in advanced breast cancer (ABC) patients (pts) after disease progression on nSAI has been considered a reasonable option in several centers.
