- Beta-catenin abnormalities and associated insulin-like growth factor overexpression are important in phyllodes tumours and fibroadenomas of the breast. Sawyer, E.J., Hanby, A.M., Poulsom, R., Jeffery, R., Gillett, C.E., Ellis, I.O., Ellis, P., Tomlinson, I.P. J. Pathol. (2003)