Squishy Science

The exciting field of molecular diagnostics is yielding some game-changing discoveries in oncology, providing hope for early intervention and increased survival rates. But are molecular and genetic biomarker assays truly the best approach for monitoring cancer progression? Conventional wisdom says yes, but innovation rarely follows convention. Results emerging from the NIH’s Physical Science Oncology Centers (PSOC) are showing the possibility of a new class of biomarkers based not on a tumor’s chemical properties, but on its physical properties. However, unlike with chemical biomarker assays that can be performed in a high throughput manner, screening for hundreds or even thousands of biomarkers at once, performing these mechanical measurements is a painstakingly slow process. “Oncologists and physicians might view this as a barrier, but as engineers, we saw it as an exciting challenge,” says Andrea Armani, part of the team who decided to tackle the problem.

“Dr. David Agus of the University of Southern California’s Keck Medical School was intrigued by recent studies which showed tumors to have very different Young’s moduli (YM) as compared with healthy tissue. But he was frustrated at the complex and slow methods used to measure this value, so he tasked my group with finding a simple and quick method to perform this measurement”, recalls Armani.

The Young’s modulus describes the amount of force needed to compress a sample, and is a measurement of elasticity (or “squishiness”). Instruments to measure YM already exist, but are cumbersome, sensitive to environmental vibrations, and require recalibration by a trained user when moved. Armani and her colleagues solved the problem with optical fiber: the sample is compressed on top of an optical fiber, which changes the polarization of the light inside, allowing the YM to be calculated (1). The new instrument is the size of a back pack, easy to use, and is fully portable.

“It is important to recognize that the fundamental field of correlating mechanical markers (such as elasticity) to cancer prognosis is relatively new. Our method could prove to be extremely useful in these studies – and because it is non-destructive, samples can be subsequently tested using molecular or cellular methods, such as genomic profiling,” says Armani.

While initial results have shown that more aggressive tumors seem to be stiffer, more research is needed. “This advancement from Dr. Armani is so exciting, as we now have a new dimension of tumor to measure,” adds David Agus.