Background: Many easily measurable and readily available factors are now established as being prognostic in primary operable breast cancer. We here applied the 2011 St Gallen surrogate definition for breast cancer subclassification using tumor grade instead of Ki67.
Patients and methods: Four thousand three hundred and eighteen consecutive patients who had surgery for primary operable breast cancer (1 January 2000 and 31 December 2009) in UZ Leuven excluding primary metastastic male breast cancers and those receiving neoadjuvant therapy. Five different surrogate phenotypes were created using the combined expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor-2 together with tumor grade. Disease-free interval (DFI), distant metastastis-free interval (DMFI), locoregional relapse-free interval (LRRFI), breast cancer-specific survival (BCSS) and overall survival (OS) were calculated.
Results: Surrogate phenotypes present with significant differences in DFI, DMFI, LRRFI, BCSS and OS. 'Luminal A' tumors presented with the best outcome parameters but the effect weakened at longer follow-up.
Conclusions: The four surrogate markers, agreed upon by the 2011 St Gallen consensus, defined five prognostic surrogate phenotypes in a large series of consecutively treated breast cancer patients. Their prognostic value changed with longer follow-up. The added value of gene expression profile over classical pathological assessment remains to be defined.