# Intraoperative Evaluation of Breast Tissues During Breast Cancer Operations Using the MasSpec Pen

## TL;DR

A handheld mass spectrometry device called the MasSpec Pen can accurately distinguish healthy from cancerous breast tissue during surgeries.

## Contribution

The study demonstrates the MasSpec Pen's ability to provide rapid, accurate intraoperative molecular analysis of breast tissues.

## Key findings

- The MasSpec Pen achieved high agreement with pathology results in predicting tissue health and cancer status.
- Statistical classifiers built from molecular data showed 95.9% agreement with postoperative pathology in intraoperative testing.
- The device successfully analyzed 273 intraoperative samples across 25 surgical cases.

## Abstract

This diagnostic study evaluates the performance of a handheld mass spectrometry device used for in vivo and ex vivo molecular analysis during breast cancer operations to discriminate healthy breast tissue from invasive ductal carcinoma.

Are molecular profiles acquired by the MasSpec Pen predictive of disease state in healthy and cancerous breast tissue?

In this diagnostic study, the MasSpec Pen was used for molecular analysis of 143 fresh-frozen healthy and invasive ductal carcinoma tissue samples in a laboratory and during in vivo and ex vivo testing in 25 surgical cases. High agreements with pathology findings were achieved for statistical prediction of healthy breast and disease state in banked, freshly excised, and in vivo tissue samples.

These findings suggest that the described technology and statistical classifiers may be useful for in vivo and ex vivo cancer detection during breast cancer operations.

Surgery with complete tumor resection remains the main treatment option for patients with breast cancer. Yet, current technologies are limited in providing accurate assessment of breast tissue in vivo, warranting development of new technologies for surgical guidance.

To evaluate the performance of the MasSpec Pen for accurate intraoperative assessment of breast tissues and surgical margins based on metabolic and lipid information.

In this diagnostic study conducted between February 23, 2017, and August 19, 2021, the mass spectrometry–based device was used to analyze healthy breast and invasive ductal carcinoma (IDC) banked tissue samples from adult patients undergoing breast surgery for ductal carcinomas or nonmalignant conditions. Fresh-frozen tissue samples and touch imprints were analyzed in a laboratory. Intraoperative in vivo and ex vivo breast tissue analyses were performed by surgical staff in operating rooms (ORs) within 2 different hospitals at the Texas Medical Center. Molecular data were used to build statistical classifiers.

Prediction results of tissue analyses from classification models were compared with gross assessment, frozen section analysis, and/or final postoperative pathology to assess accuracy.

All data acquired from the 143 banked tissue samples, including 79 healthy breast and 64 IDC tissues, were included in the statistical analysis. Data presented rich molecular profiles of healthy and IDC banked tissue samples, with significant changes in relative abundances observed for several metabolic species. Statistical classifiers yielded accuracies of 95.6%, 95.5%, and 90.6% for training, validation, and independent test sets, respectively. A total of 25 participants enrolled in the clinical, intraoperative study; all were female, and the median age was 58 years (IQR, 44-66 years). Intraoperative testing of the technology was successfully performed by surgical staff during 25 breast operations. Of 273 intraoperative analyses performed during 25 surgical cases, 147 analyses from 22 cases were subjected to statistical classification. Testing of the classifiers on 147 intraoperative mass spectra yielded 95.9% agreement with postoperative pathology results.

The findings of this diagnostic study suggest that the mass spectrometry–based system could be clinically valuable to surgeons and patients by enabling fast molecular-based intraoperative assessment of in vivo and ex vivo breast tissue samples and surgical margins.