Abstract OT1-06-05: Atomic force microscopy (AFM) - a novel nanotool for cancer diagnostics: A prospective, blinded study of nanomechanical profiling of human breast tissue as a potential biomarker for stratifying low- and high-risk breast cancer subtypes
Authors: Burian R , Appenzeller T , Oertle P , Raez C , Lim R , Forte S , Dellas S , Münst S , Obermann E , Plodinec M 
Published: February 2018

Abstract
Background
The crucial point in making treatment decisions for breast cancer patients is the assessment of tumour aggressiveness. The established prognostic markers may be insufficient to stratify cancer patients into treatment relevant risk groups. Emerging evidence indicates that mechanical properties of cancer cells and their microenvironment that occur on a nanometre scale play a critical role in cancer invasion and metastases. Therefore, detecting these nanomechanical changes could serve as biomarker of cancer aggressiveness.
Trial design
We conduct a prospective, blinded study in a routine clinical setting. Using minimal invasive breast biopsies we measure the nanomechanical (stiffness) properties of human breast tissue with our atomic force microscope (AFM) based method known as ARTIDIS (Automated and Reliable Tissue Diagnostics). These properties can only be measured using fresh (non-fixed) tissue under physiological conditions (Custodiol transplant buffer). This novel method is based on the use of a micro-fabricated 20nm-sharp tip that indents several thousand individual locations across tissue specimens within 60-180 minutes. Each indentation effectively measures the stiffness of local structures (e.g. cancer cells, extracellular matrix) located under the tip. Thus we obtain a quantitative, biopsy-wide, nanomechanical profile. Post-AFM the same biopsy is used for routine histopathological diagnosis, the current diagnostic gold standard to which the nanomechanical profile is then correlated.
Eligibility criteria
All women undergoing a minimal invasive breast biopsy (core needle or vacuum assisted biopsy) at the breast centre of the University of Basel.
Exclusion criteria: age younger than 18years, necrotic/disintegrated biopsy, and technical limitations
Specific aims
Our primary endpoint is to differentiate benign from cancerous breast lesions based on their nanomechanical properties. Our secondary endpoint is to subclassify biopsies with cancerous lesions into the current four main breast cancer subgroups (Luminal A, Luminal B, HER2+ and basal-like).
Statistical analysis
The full dataset will include all patients with valid AFM measurements. Primary analysis: the proportion of true positive results divided by the total number of patients with malignant tumour (sensitivity) will be estimated and presented together with its 95% confidence interval. The histological diagnosis of the same biopsy as analysed by AFM will serve as gold standard.
Present accrual and target accrual
Present accrual as of June 12, 2017: 200 breast tissue biopsies.
Target accrual is 508 biopsies. This will allow for a power of 0.8 and a sensitivity of 90%.
Contact information: Rosemarie.Burian@usb.ch
Citation Format: Burian R, Appenzeller T, Oertle P, Raez C, Lim R, Forte S, Dellas S, Münst S, Obermann E, Plodinec M. Atomic force microscopy (AFM) - a novel nanotool for cancer diagnostics: A prospective, blinded study of nanomechanical profiling of human breast tissue as a potential biomarker for stratifying low- and high-risk breast cancer subtypes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT1-06-05.