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Smart knife can tell cancer cells from healthy tissue

Thursday 18 July 2013

"Tumour 'sniffing' surgical knife designed," BBC News reports, while the Metro tells us that this "smart scalpel allows surgeons to perform riskier, more effective, operations".

Many other papers report on the 'iKnife', which is a clever combination of two existing pieces of technology – an electrosurgical knife and a mass spectrometer. This technology enables surgeons operating on a cancer patient to tell quickly if tissue is cancerous or not by looking at its chemical profile. The electrosurgical knife creates a "surgical smoke" when it vaporises a patient's tissue, and this "smoke" is sucked up the knife and analysed by the attached mass spectrometer.

At present, surgeons find it difficult to tell whether the tissue surrounding a tumour is normal or cancerous. Sending samples of tissue for analysis during surgery is time consuming (which is a risk to the anaesthetised patient) and costly. A fast, reliable diagnostic tool providing on-the-spot analysis would be of great benefit to surgeons.

To test how accurate the iKnife was in detecting cancer tissue, the researchers created a database of tissue samples analysed in the traditional way. They then used the iKnife “live” in the operating theatre to analyse tissue taken from 81 cancer patients during surgery and compared the results to the reference samples. The tests showed that the tissue analysis by the iKnife matched the analysis of tissue undertaken in the laboratory, with acceptably few inaccuracies.

This exciting study suggests that the iKnife technology could improve the accuracy of surgery for cancer. Further research is required to find out if it can reduce cancer recurrence or improve survival rates.

Where did the story come from?

The study was carried out by researchers from Imperial College London and was funded by a number of public research institutions including the National Institute for Health Research. The study was published in the peer-reviewed journal Science Translational Medicine.

The media love a good news story, so it’s not surprising that this research was widely covered. With the help of an accompanying press release, most reports got the details right. Whether the iKnife can save thousands of lives, as claimed by the Express, or will be a “game changer”, as reported in the Metro, remains to be seen. The claim that the knife “sniffs out” cancer is misleading. The knife is not designed to be a diagnostic tool for finding cancer in people with symptoms, but to be used by surgeons operating on patients who have been diagnosed with cancer.

The Independent’s claim that the iKnife could curb the spread of cancer is a little inaccurate. The knife may help surgeons ensure that they have removed all the cancerous tissue (which could stop it spreading), but use of the knife doesn’t, in itself, curb cancer’s spread.

What kind of research was this?

This study was designed to test the accuracy of the “intelligent knife” – dubbed the iKnife – for analysing tissue samples removed from cancer patients in the operating theatre. The iKnife is a conventional electrosurgical knife, connected to technology called rapid evaporative ionisation mass spectrometry (REIMS). REIMS analyses the chemicals in tissue to identify the characteristics and type of cells present. When the knife is used to cut through tissue it vaporises some of it, creating a “surgical smoke”, which is sucked into the spectrometer for analysis.
The authors say that, at present, when patients have cancerous tumours removed, it is not always easy for surgeons to know if they have removed all the cancerous cells. They often remove a tiny border of healthy tissue at the tumour “margins”, but they also need to minimise removal of healthy, non-cancerous tissue for structural, functional and, occasionally, cosmetic reasons.

Where there is any uncertainty, removed tissue is often sent to the lab for analysis while the patient remains under general anaesthetic. Additional samples may be required. This procedure takes time, is costly and may lead to inaccuracies, the researchers argue. Inaccuracies may then require further surgery to correct.

The researchers cite evidence that suggests that, out of every five breast cancer patients who have breast conserving surgery, one requires a further operation to remove remaining cancer cells.

By contrast, they say, the iKnife is designed to analyse whether tissue is cancerous or healthy in seconds. It has been shown to be successful in animal models but this was the first test of the technology in human patients.

The objective was to test the iKnife in a surgical situation and to assess its accuracy in the detection of “tumour margin status” in patients undergoing removal of tissue from brain, liver, lung, breast and colorectal tumours.

What did the research involve?

Before using the iKnife in theatre, the researchers used the technology to analyse samples of tissue taken from 302 patients using traditional laboratory methods. The samples came from the patients’ stomach, colon, liver, breast, lung and brain.

From this data they created a reference library of nearly 3,000 cell types, recording their characteristics from the chemicals identified in tissue cells.

Of these cell types, 1,624 were cancerous, 1,231 were healthy and 78 were from patients with benign inflammatory bowel disease.

The iKnife, connected to the spectrometer, was then used in real tumour removal operations in the operating theatre. The researchers were able to analyse tissue taken from 81 operations on cancer patients. They compared these results with those from the reference database they had previously created.

What were the basic results?

The researchers found that in all 81 tests the tissue type identified by the iKnife during surgery matched the analysis of tissue based on traditional methods.

How did the researchers interpret the results?

The researchers say the study provides “compelling evidence” that the REIMS-iKnife can be used in a wide range of operations for cancer, with the potential to improve patient outcomes, minimise surgical trauma and prevent the unnecessary removal of healthy tissue.


The iKnife looks likely to be a promising development in cancer surgery.

One of its advantages is the speed with which it analyses tissue. This, the authors say, means that feedback takes less than 2.5 seconds. This includes sampling, sample transfer, chemical
analysis, data processing and production of results. This is clearly very fast compared with the estimated 30 minutes it takes using the traditional technique of looking at tissue samples under the microscope while the patient is still anaesthetised.

The researchers mention some drawbacks to bringing this technology into general use, including the fact that the development of the spectrometer and of the database will take time, effort and money. They suggest that, at first, it will not be possible to identify every tissue type that may be encountered (for example, some very rare tumour types) so that identifying the edges of rarer tumours may not be possible.

As the authors point out, this was the first ever test on human patients, so further testing of the iKnife’s accuracy in analysing tissue against traditional methods is required. Whether it can improve the precision required for accurately marking the edges of tumours at surgery or improving patient outcomes and survival rates has yet to be explored.

The iKnife is an innovative piece of technology that could potentially lead to improvements in both surgical outcomes and cancer survival.

Analysis by Bazian
Edited by NHS Website