A cancer patient can spend hours in surgery, only to discover afterwards that a small piece of the tumour was left behind – and that means a second arduous procedure. It’s a common, distressing outcome for the patient.
There are a few ways to try and avoid this. Depending on the cancer and its location, a surgeon might opt to take additional healthy tissue in an attempt to avoid the possibility of a follow-up procedure. Or, if the hospital has the facilities, frozen section analysis can be carried out. Here, the patient lies open on the operating table for longer, while excised tissue is sent to the lab, frozen, sectioned, stained and examined under a microscope by a pathologist. It’s time-consuming but highly accurate. Though some cancers can be altered in the freezing process, making diagnosis less cut and dry.
A team from the University of Texas at Austin wants to change all this, with a new invention: a disposable pen that diagnoses tissue samples, mid-operation, within ten seconds, at an accuracy of 96 per cent.
“My idea with the MasSpec Pen was to develop a fully automated medical device that was also completely biocompatible and non-destructive to tissue samples,” says Livia Schiavinato Eberlin, an assistant professor of chemistry at the University of Texas at Austin. “The result is a device that has a very elegant but simple design and operation, in a way that can be handled by any medical professional.”
Read more: Marcus Krause's lung cancer wouldn't stop growing. Then he took a new kind of blood test
As the name suggests, the pen uses mass spectrometry to make diagnoses. It consists of a handheld probe with a plastic tip that is used to touch the tissue sample mid-surgery. A pump system then sends a single drop of water to the pen tip, which sits on the tissue for three seconds.
“During this time, molecules that are soluble in water like small metabolites including sugars, lipids, amino acids, and even some proteins are extracted from the tissue,” Eberlin says. “This is a very gentle chemical process, and what is incredible and exciting is that it causes no obvious harm to the tissue. You can think about it in the same way that water extracts caffeine from coffee powder, we use water to extract molecules from tissue."
The droplet passes from the pen down a 1.5 metre tube attached to a mass spectrometer that analyses the molecules on the spot to get what Eberlin refers to as a “fingerprint” of the tissue. “We envision the mass spectrometer to be in a cart and go in ORs for use, and the pens are the disposable components that would be used for each procedure,” she says. A wash cycle occurs after each analysis, to get rid of 97 per cent of any potential contamination ahead of a repeat analysis – or the tip of the pen can be replaced.
“We analysed a lot of human normal and cancer tissues, 253 to be exact, so that now we can associate the molecular profiles to a cancer ‘fingerprint’ or a normal ‘fingerprint’ and provide a diagnosis using statistical and software tools,” Eberlin says. The team looked at breast, thyroid, lung and ovarian cancers, but Eberlin says she has used mass spectrometry to identify brain, pancreatic, stomach, bladder, kidney, prostate and liver cancer in the past and has no reason to believe the pen’s abilities can’t extend to all solid cancers eventually.
Eberlin, who worked on the pen with Tom Milner from the university's biomedical engineering department, the Baylor College of Medicine and the MD Anderson Cancer Center, adds this is far from the first time a team has suggested using mass spectrometry for clinical use. The iKnife, developed several years ago, burns tissue as it cuts so that a mass spectrometer can analyse the smoke. The difference with the MasSpec Pen? It can safely interact with tissue in surgery and perform a diagnosis, without causing any damage.
“That is something that was a challenge in the field, which we achieved by designing and engineering a system that is fully automated and is based on water for molecular analysis and materials that are biocompatible.”
The team plans on following up the study with small surgical trials at the Texas Medical Center next year.
This article was originally published by WIRED UK
