It's difficult for surgeons to remove tumors at the exact place where growth becomes flesh, cutting too much or too little could be dangerous to the patient. The new "smart knife" may have a solution.

The knife "sniffs" the smoke coming off the incision and lets the surgeon know if the tissue contains any cancer cells, Science Now reported.

The tool measures lipid (fatty molecule) levels in the cells to distinguish between tumor and flesh. Different levels indicate different types of tissue.

Lipids could only be tested through a process called mass spectrometry, which requires the tissue to be removed before it was analyzed.

This new scalpel speeds up the process by analyzing smoke created by the incisions, the Imperial College team dubbed their invention "intelligent knife" or iKnife.

Hungarian chemist Zoltán Takáts, the tool's creator, described the smoke as "a very nasty tarry mixture." The dark smoke could save lives; the vapor contains iodized molecules which allows the knife to identify the presence of cancer.

 "It's real-time information," Takáts said.

The scalpel was first tested on animal tissue, and then during real human operations. The team collected about 3,000 cancerous and non-cancerous tissue samples from 300 patients and tested them with both conventional methods and the new knife.

The knife proved to be able to distinguish between organ and tumor tissue in the breast, liver, and brain. It was then used in 81 actual surgeries.

The knife has a one to three second delay, but is expected to cut down on the amount of time the patient is in surgery and under anesthesia.

Methods for quickly detecting cancerous tissue have been created before, but always required injecting the patient with dyes.

IKnife will be more efficient because the process "is no different from what [physicians] normally do," Jeremy Nicholson, a biochemist who heads Imperial College's department of surgery and cancer, said.