| Abstrakt: |
Purpose: A previous cohort study of 759 women with invasive T1 T2 breast cancer operated on with breast conserving surgery in Stockholm between 1976 and 1986 indicated that age <50 years, no postoperative irradiation, and nodal involvement were independent risk factors for ipsilateral breast tumor recurrences (IBTR). The aim of the current study was to analyse if selected biological markers assayed in tumor specimens from these patients could add prognostic information, thereby helping to identify groups of patients at high versus low risk of IBTR. Methods: The study was designed as a case control study ‘nested’ within the cohort. The cohort was stratified according to nodal status and the use of postoperative irradiation. In these four strata, the cases were those 80 women who developed IBTR between 1977 and 1994. In each stratum, women without IBTR were randomly selected as controls (n=159). Median time at risk was 12 (8–18) years. The following factors were analysed: histopathological tumor grade according to Elston–Ellis, DNA ploidy, immunohistochemical staining for apoptosis, angiogenesis, Ki 67 (MIB 1), c erbB 2, p 53, waf 1, and bcl 2. The prognostic role of each factor was assessed using linear logistic regression methods. Results: In univariate analyses only age <50 years was identified as a significant risk factor for IBTR, whereas none of the studied biomarkers yielded statistically significant information. However, in a multivariate model, age, MIB-1-index, and tumor grade significantly influenced the risk for IBTR: the odds-ratio (OR) for age ≥50 years was 0.4, 95% confidence interval (CI) = 0.2–0.9; for medium or high grade tumors it was 0.4 (CI = 09–0.9); and for MIB-1-index >30%, 2.1 (CI = 1.0–4.4). In women ≥50 years, MIB-1-index >30% was associated with an OR of 3.5 (CI = 1.4–8.8) compared to those who were younger. Patients ≥50 years with MIB-1-index ≤30% were thus identified as a low-risk group with an OR of 0.2 (CI = 0.1–0.5). A possible high-risk group was patients <50 years with tumors showing a combination of c-erbB-2 and waf-1 immunoreactivity, with an OR of 6.7 (CI = 1.3–34.7). Conclusion: Women ≥50 years with MIB-1-index ≤30% constituted a subgroup with a low risk of IBTR. This observation raises the issue whether this group of patients might be spared postoperative irradiation following breast-conserving surgery. However, due to the methodology of the study, including the large number of comparisions, the presented results warrant cautious interpretation and should be regarded as tentative. [ABSTRACT FROM AUTHOR] |
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