Clinical outcomes of patients with T1N0 breast cancers: how important are biological risk factors?.

Abstract

Abstract Abstract #2078 Background: Tumour size (T) and nodal status (N) have traditionally been regarded as the most important prognostic factors which determine individual recommendations for adjuvant treatment. Early trials of adjuvant systemic therapy relied on nodal status as the key determinant of recurrence risk, with node negative patients (pts) often excluded due to their 'low risk' classification. With greater understanding that predominant growth signalling pathways in a given tumour may be of greater importance than size and nodal spread, current clinical practice places greater emphasis on high risk biological factors. Factors include young age (<35y), HER2 positivity (pos), grade III status, absence of hormone receptors (HR), and triple negative (TN) phenotype. Presence of these features will likely influence systemic treatment recommendations. With this in mind we examined data which has been prospectively collected to determine the outcomes of pts with high risk T1N0 tumours and compared them to pts with lower risk biological profiles.
 Methods: Data on 2285 pts with early breast cancer were analysed. Comparisons were made between T1N0 high risk pts (defined as having one or more of the following features: age<35, grade III, HER2 pos, or TN) and pts with good biological prognostic features (defined as the absence of all the above factors) in the following subgroups: 1) T1N0, 2) T1N1-2, and 3) T2-3N0. In addition outcomes were specifically assessed in T1N0 pts with Her2 pos vs negative disease; TN vs non-TN.
 Results: 401 pts with T1N0 high risk tumours were identified (T1N0HR). In the low risk group there were 330 pts with T0 tumours (T1N0LR), 286 pts with T1Npositive tumours (T1NposLR) and 154 pts with T2/T3N0 tumours (T2/3N0LR). There were 137 pts T1N0 Her2 pos (T1N0H2). The median follow up for all pts was 3.4 yrs (0.5-36). Treatment given and clinical outcome for each pt group are shown in the table.
 
 The majority of DFS events in the T1N0H2 pts occurred in those not receiving adjuvant trastuzumab (12.4% vs 2.2%). TN tumours were seen in 12.5% of pts studied. Despite the use of systemic therapy in 97.5% of TN pts (vs 64% in non-TN) , there was a higher DFS event and death rate (18% vs 15%; and 13% vs 6% respectively)
 Conclusions: Outcomes for T1N0HR pts were similar to that of T1N0LR and T2/3N0LR pts, possibly related to the greater use of systemic therapies in the T1N0HR pts (89% vs 50% vs 79%). Despite the high rate of adjuvant systemic therapy, the outcomes for the T1N0HR group were inferior to the outcomes for pts in the T1NposLR group (DFS 15.7% vs 9.8%) supporting the view that biological factors may be a more important determinant of outcome than nodal status. Similarly, even in pts with small tumour size, triple negative phenotype had worse outcome. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2078.