A team of engineers and scientists has developed a “pen” that accurately identifies cancerous tissues during surgery within 10 seconds. This handheld instrument could one day be used by surgeons to quickly determine what tissue to cut and preserve. The instrument, called MasSpec Pen, was tested on tissue from 253 patients and found to distinguish between cancerous and healthy tissue with ~ 96% accuracy. When a patient undergoes surgery to get rid of a tumor, a surgeon tries to remove all cancerous tissue while preserving the healthy tissue. Although maximizing cancer removal is critical to improving patient survival, removing too much healthy tissue can also have profound negative consequences for patients. For example, breast cancer patients could experience higher risk of painful side effects and nerve damage. Thyroid cancer patients could lose speech ability or the ability to regulate the body’s calcium levels in ways that are important for muscle and nerve function. The current technology is called frozen section analysis, and it takes 20-30 minutes for a pathologist to prepare and analyze the sample. Because the metabolites in rapidly dividing cancer and normal cells are so different, MasSpec Pen extracts molecules from the patient’s tissue with a tiny amount of water and then sends them through tubes to an instrument that can identify the molecular fingerprint of cancer. When the analysis is complete, the words “Normal” or “Cancer” automatically appears on a computer screen. For certain cancers, such as lung cancer, the name of a subtype can also be predicted. MasSpec Pen seems to be a big improvement on current methods, and the researchers hope to start testing it during oncologic surgeries in 2018.