Axillary surgery has undergone considerable changes in recent years, especially in relation to patients who undergo neoadjuvant chemotherapy (NACT). Due to constantly decreasing rates of recurrence ...and death from breast cancer, modern surgical strategies aim at de-escalating the extent of local treatment and avoiding unnecessary procedures. This relates especially to lymph node surgery which is associated with considerable morbidity. In patients who initially present with clinically node-negative disease, sentinel lymph node biopsy (SLNB) is increasingly performed after NACT. The determination of the post-NACT nodal status does not only spare patients from additional surgery but also allows the assessment of pathologic complete response which is increasingly becoming an important tool for treatment planning. Since more than 70% of these patients have a ypN0 status after NACT, future trials will aim to identify patients who might be spared any axillary surgery after NACT. In patients who initially present with positive lymph nodes, the success rates of SLNB in terms of detection and accuracy are less favorable compared to those in patients who undergo primary surgery. The clinical significance of this is unclear. To reduce unnecessary axillary dissection in patients with cN1ycN0 status, prospective outcome data after SLNB without further lymph node removal are urgently needed. Improvements in surgical technique by localizing positive nodes at the time of diagnosis and removing them in a targeted surgical procedure (targeted axillary dissection) are under evaluation. Risk assessment and patient selection (including gene expression profiles) might be other ways of safely omitting axillary dissection.
Abstract
Purpose: Studies have shown that the 70-gene signature (MammaPrint®) (MP) may outperform clinicopathological risk assessment and may predict the benefit from chemotherapy (CT) in patients ...(pts) with early-stage breast cancer. However, the need of fresh tissue and the high cost of the assay limit its use in daily clinical practice. We investigated whether 1) tumor clinicopathologic features can predict MP risk (high vs. low); 2) MP results could help to make decisions for the use of CT in pts with ER positive (ER+ve) breast cancer beyond recommendations of known international guidelines (NCCN, St. Gallen).
Patients and methods: Women with operable invasive breast cancer without evidence of distant disease undergoing surgery at the Breast Surgery Department were enrolled into the study. A 3 mm punch biopsy of the tumor was obtained from the specimen within the first hour after surgery. Samples were shipped to the laboratory in an RNA-stabilizing solution and were studied to ensure the presence of at least 30% of tumor cells and a customized microarray containing 70 genes was analyzed as described by the manufacturer.
Results: 124 consecutive pts were enrolled into the study; 106 tumor samples were adequate for the microarray. Median age was 53 yrs (range 28–83), mean tumor size was 2.3 cm (SD ±1.34), 52.4% pts had pN0, 55% of tumors had Ki-67 ≥20% and 36% were poorly differentiated. ER were detected in ≥50% of cells in 82% and <1% of cells in 15% of tumors, respectively; HER2 was positive in 18% of tumors.
As expected, poorly differentiated, ER and PgR negative, HER2 positive and highly proliferating tumors were more likely to be classified as high-MP. We then focused our analysis on ER and PgR +ve, HER2 negative tumors and assessed features correlated with MP results in this subgroup. Unexpectedly, 31/80 (39%) of these tumors were classified as high-MP vs. 49 (61%) low-MP. We found that tumor size (T1 vs. T2-T4), poor differentiation (G3 vs G1-2) and high proliferation (Ki-67 ≥20%) were significantly associated with a high-MP result. In an exploratory multivariate analysis tumor size and Ki-67 remained as independent predictors of high-MP result. At last, when we compared MP risk with recommendations for AT from international guidelines we found that in the subgroup of candidates for endocrine therapy (ET) in whom the benefit from the addition of CT is undetermined, 25/68 pts (37%) were high-MP and 43 pts (63%) low-MP. When we considered recommendations for AT proposed by our multidisciplinary team according to international guidelines, 11/25 pts (44%) with high-MP received ET only and 14 pts (56%) CT + ET, while among 43 pts with low-MP only 9 received both CT and ET.
Conclusions: Our study shows that the 70-gene signature was feasible in the clinical setting, as 85% of tumor samples were adequate. A substantial proportion of ER/PgR+ve, HER2 negative tumors was classified as high-MP; within this subgroup, proliferation and tumor size independently predicted high-MP results. In 20 pts, MP risk would have resulted in discordant recommendations for AT compared to those based on standard clinicopathologic features.
Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-27.
Abstract
Background The level of estrogen receptor (ER), progesterone receptor (PR) and HER2 expression is predictive for prognosis and/or treatment response in breast cancer patients. However, ...differences in fixation and IHC and subjective interpretation can substantially affect the accuracy and reproducibility of the results. The commercially available TargetPrint test measures the mRNA expression level of ER, PR and HER2 and provides high quality second opinion for local IHC/FISH assessment. This study compares results from the microarray-based TargetPrint with IHC and FISH (for HER2 IHC2+) generated by local standard procedures.
Methods Prospective tumor samples were collected for 749 patients diagnosed with breast cancer stage I to IV between February 2008 and January 2011. The mRNA level of ER, PR and HER2 (TargetPrint) was assessed in the Agendia laboratories (Agendia Inc, Irvine, CA; Agendia BV, Amsterdam, the Netherlands) in fresh tumor samples submitted from 22 hospitals from Europe, New Zealand, Japan and US. The results of the IHC/FISH assessments performed according to the local standards at the hospitals were compared to the quantitative gene expression readouts.
Results Of the 749 samples, IHC assessment was unknown for 5 ER samples and 4 PR samples; FISH was unknown for 24 samples. TargetPrint read out was not assessed for HER2 for 11 samples.
Median age of these patients was 61 years. Comparison of IHC and gene expression read out by TargetPrint showed a concordance of 95% for ER; 82% for PR and 91% for HER2.
In this study, only 4% of all IHC ER positive samples were classified negative by microarray. In contrast, 14% of IHC ER negative samples were classified positive by microarray. However for HER2, 28% of IHC/FISH HER2 positive samples were classified negative by microarray and 5% of IHC/FISH HER2 negative samples were classified positive by microarray.
Samples with discordant classifications for TargetPrint and local assessment are being reviewed in greater detail by a central pathologist.
Conclusions Microarray based readout of ER, PR and HER2 status using TargetPrint is highly comparable to local IHC and FISH analysis in 749 analyzed samples in various hospitals worldwide. The results indicate mRNA expression read out for ER, PR and HER2 by TargetPrint provides high quality second opinion for local IHC/FISH assessment.
Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-11-09.
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