Berner Kantonalbank

We develop a dynamical symmetry approach to path integrals for general interacting quantum spin systems. The time-ordered exponential obtained after the Hubbard-Stratonovich transformation can be disentangled into the product of a finite number of the usual exponentials. This procedure leads to a set of stochastic differential equations on the group manifold, which can be further formulated in terms of the supersymmetric effective action. This action has the form of the Witten topological field theory in the continuum limit. As a consequence, we show how it can be used to obtain the exact results for a specific quantum many-body system which can be otherwise solved only by the Bethe ansatz. This represents an example of a many-body system treated exactly using the path-integral formulation. Moreover, our method can deal with time-dependent parameters, which we demonstrate explicitly.

525 Background: Today, many women with node-negative, hormone receptor positive breast cancer receive adjuvant chemotherapy followed by endocrine therapy. However, the majority of these patients would never have experienced a relapse and would have been sufficiently treated with endocrine therapy alone. Aim of our study was to identify DNA methylation markers associated with a low risk of recurrence after tamoxifen monotherapy. Methods: As a first step, we performed a genome-wide screening for DNA methylation markers associated with the risk of recurrence after tamoxifen monotherapy. The best candidates were then validated in a population of 278 patients using a microarray approach. Results: We identified several DNA methylation markers with a strong relation to clinical outcome (cox proportional hazard model, p<0.05). In a multivariate model, DNA methylation contributed significant information to conventional factors such as grade, tumor size, or estrogen receptor expression level. Furthermore, by combining three markers into a methylation score and defining a cut-off, we identified a group with excellent outcome when treated with tamoxifen alone (disease-free survival 95 % at 10 years, versus 62 % in the poor prognosis group). Validation in an independent patient cohort is currently in progress. So far, the best marker has already been validated (p<0.05). Conclusions: These results provide substantial evidence that DNA methylation could be used to predict outcome in node-negative patients with tamoxifen monotherapy, and to identify low risk groups which may not require additional cytotoxic treatment. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Epigenomics AG Epigenomics AG Epigenomics AG Epigenomics AG Epigenomics AG