An interdisciplinary team of researchers based in Austin, Texas have developed a handheld device that accurately analyses tissue samples in vivo enabling real-time cancer diagnosis during surgery.

When treating cancer, surgeons often remove the whole tumour with a margin of healthy tissue. If the margin is too big then healthy tissue will have been removed unnecessarily, and this can negatively affect organ function. More worryingly, if the margin is too small then cancerous cells left in a patient’s body may spread to other areas and/or the patient may require further surgeries. At present, tissue from the margin removed during surgery is analysed either after surgery to determine if the margin was healthy or, in some cases, during surgery using frozen section analysis. However, frozen section analysis has its drawbacks since it requires tissue to be cut, frozen, stained then visually inspected by a pathologist, which takes at least 30 minutes and can lengthen surgery. Furthermore freezing tissue often causes structural damage, which can prevent accurate results from being obtained. It is clear that surgeons and patients would benefit from real-time analysis during surgery, but previous attempts to provide rapid analysis of cancer tissues have not been successful. The iKnifeTM can identify cancerous cells in real-time, but due to electrocauterisation causes unacceptable tissue damage. DESI-MS is effective in a laboratory setting, but is not suitable for in vivo use due to a reliance on organic solvents, high-pressure gas and high voltage.

A new device has been developed to address all of the above-mentioned problems, and which could potentially provide real-time cancer diagnosis in a theatre setting without causing tissue damage. The MasSpec Pen is a new handheld device that was designed and tested by a team comprising chemists, engineers, pathologists and surgeons. It comprises a disposable 3D-printed tip that uses a droplet of water to extract molecules from a tissue sample, which when analysed, enables the identification of cancer biomarkers including metabolites, lipids and proteins.

Whilst being developed, the MasSpec Pen was initially used to analyse thin tissue mouse brain and human breast samples ex vivo to show that it could distinguish between cancerous tissue and healthy tissue. The researchers then analysed soft tissue samples from a range of organs including the brain, breast, thyroid, lungs and ovaries to show that the MasSpec Pen was non-destructive and to show that it was not limited to use with thin tissue samples. Next the researchers analysed samples containing a mix of cancerous and healthy tissue to show that the device could be used to distinguish cancerous tissue from healthy tissue within a margin. Finally, the researchers tested the MasSpec Pen using live mice, successfully demonstrating that the device could distinguish cancerous tissue from healthy tissue without harming the tissue. This research shows that the MasSpec Pen could be used by surgeons to determine how big a margin needs to be removed during surgery without harming the patient or lengthening the surgery.

One potential difficulty is that, although the MasSpec Pen itself is small, it needs to be attached to a much larger device: a mass spectrometer. The MasSpec Pen is used to extract molecules from a tissue sample for analysis, but it is the mass spectrometer that analyses the extracted molecules. Mass spectrometers are large and expensive machines commonly found in research facilities and forensic laboratories; they are not commonly found in hospitals. Therefore, for the MasSpec pen to be used in operating theatres, smaller and less expensive mass spectrometers will need to be developed.

Preliminary data suggests that the MasSpec Pen can diagnose cancer with an overall accuracy of >96% in 10 seconds or less. Clearly more research needs to be done to establish the effectiveness of the MasSpec Pen during surgery on human patients and mass spectrometers suitable for use in operating theatres need to be developed. Nonetheless, this device has the potential to be of substantial benefit to patients undergoing cancer surgery.