- Letrozole, a new oral aromatase inhibitor for advanced breast cancer: double-blind randomized trial showing a dose effect and improved efficacy and tolerability compared with megestrol acetate. Dombernowsky, P., Smith, I., Falkson, G., Leonard, R., Panasci, L., Bellmunt, J., Bezwoda, W., Gardin, G., Gudgeon, A., Morgan, M., Fornasiero, A., Hoffmann, W., Michel, J., Hatschek, T., Tjabbes, T., Chaudri, H.A., Hornberger, U., Trunet, P.F. J. Clin. Oncol. (1998)