Purpose: Insulin-like growth factor-II (IGF-II) is an important regulator of tumor growth in breast cancer. In this study we have examined the prognostic value of IGF-II mRNA expression in breast cancer and its relationship to other predictive parameters.
Patients: Sixty-eight women with infiltrating ductal carcinoma were given the same treatments including mastectomy and antitumoral therapies and followed up for 5 years.
Results: The overall 5-year survival rate was 73.5% (55/68). IGF-II mRNA was expressed in 33/64 patients (51.6%) and had no significant impact on survival. The expression of estrogen receptor (ER) and progesterone receptor (PgR) did not significantly affect the 5-year survival, but in the presence of an IGF-II mRNA signal, the survival of ER- and PgR-negative patients (n=9) was lower than that of ER- and PgR-positive patients (n=15), although the difference was not significant. The 5-year survival was not significantly different between Ki-67-positive and negative patients, but in the IGF-II positive group Ki-67-positive patients (n=7) had a significantly poorer prognosis than Ki-67-negative patients (n=26). The expression of p53 protein was associated with a poorer prognosis: 6/11 (54.5%) p53-positive patients died in the first 26 months of follow-up and 5 of these 6 patients (83.3%) also had positive IGF-II mRNA expression.
Conclusions: IGF-II mRNA expression per se is not an independent predictive factor in breast cancer but may be a marker of poor prognosis when associated with other prognostic factors such as Ki-67 index and p53 expression.