- Polymorphisms of the repeated sequences in the enhancer region of the thymidylate synthase gene promoter may predict downstaging after preoperative chemoradiation in rectal cancer. Villafranca, E., Okruzhnov, Y., Dominguez, M.A., García-Foncillas, J., Azinovic, I., Martínez, E., Illarramendi, J.J., Arias, F., Martínez Monge, R., Salgado, E., Angeletti, S., Brugarolas, A. J. Clin. Oncol. (2001)