ABSTRACT
Axillary lymph node involvement is an important prognostic factor for breast cancer survival but is confounded by the number of nodes examined. We compare the performance of the log odds prognostic index (Lpi), using a ratio of the positive versus negative lymph nodes, with the Nottingham Prognostic Index (NPI) for short-term breast cancer specific disease free survival. A total of 1818 operable breast cancer patients treated in the University Hospital of Leuven between 2000 and 2005 were included. The performance of the NPI and Lpi were compared on two levels: calibration and discrimination. The latter was evaluated using the concordance index (cindex), the number of patients in the extreme groups, and difference in event rates between these. The NPI had a significant higher cindex, but a significant lower percentage of patients in the extreme risk groups. After updating both indices, no significant differences between NPI and Lpi were noted.
ABSTRACT
AIM: Basal-like breast tumours, as defined by microarrays, carry a poor prognosis and therapeutic options are limited to date. Often, these tumours are defined as oestrogen receptor (ER) negative/progesterone receptor (PR) negative/human epidermal growth factor receptor 2 (HER-2) negative (triple negative) by immunohistochemistry (IHC), but a more complete definition should include expression of basal cytokeratins (CK5/6, CK14 or CK17) and/or human epidermal growth factor receptor 1 (HER-1). The aim of this study was to investigate to what extent CK5/6 and HER-1 characterise the group of triple negative breast cancers. METHODS: Expression of CK5/6 and HER-1 was studied by IHC in 25 triple negative breast carcinomas and 32 grade-matched, non-triple-negative controls. All 57 cases were further subjected to fluorescence in situ hybridisation to investigate HER-1 gene copy number. RESULTS: CK5/6 and HER-1 expression was most frequent in triple negative tumours: 22 out of 25 cases (88.0%) expressed at least one of these markers (60.0% CK5/6 positive and 52.0% HER-1 positive). In the control group, CK5/6 and HER-1 expression was found in ER-negative but not in ER-positive tumours (ER negative/PR negative/HER-2 positive tumours: 20.0% CK5/6 positive and 46.7% HER-1 positive). HER-1 gene amplification was found in five cases only: four triple negative (16.0%) and one ER-negative control (ER negative/PR negative/HER-2 positive, 6.7%). Of interest, all five HER-1 amplified cases showed a remarkably homogeneous HER-1 expression pattern. CONCLUSION: Expression of CK5/6 and HER-1 is frequent in ER-negative breast cancers, in triple negative and in non-triple negative tumours. In a minority of cases, HER-1 overexpression may be caused by HER-1 gene amplification. Further studies are needed to investigate whether such cases might benefit from anti-HER-1 therapy.
