Scientists have developed a new robo-surgeon that can remove cancerous tumors from extremely delicate locations that can prove challenging and risky for even the most experienced human surgeons.

When removing cancerous tumors, a process known as resection, the aim is to preserve as much healthy tissue as possible while removing the cancerous cells to prevent them from returning or spreading again. This is a challenging operation at the best of times, but even more so when the affected area is the on the neck, head, or other delicate areas.

Even for the most experienced surgeons, this can be a tense task, but add to that the mental and physical obstacles introduced by fatigue, burnout, and visual obstruction, and the steadiest of hands may well struggle to perform correctly.

But this issue may soon become a thing of the past. That is, if the new ASTR – Autonomous System for Tumor Resection – has anything to do with it. ASTR was designed by a team of researchers from Johns Hopkins University to perform resections in delicate places, like the tongue. According to its creators, the robot surgeon can remove tumors with accuracy that rivals “or even potentially” exceeds human surgeons.

“Doing a resection that has precise margins is a super difficult task,” Axel Krieger, assistant professor of mechanical engineering at the Whiting School of Engineering, said in a statement.

“So much of these surgeries is hope and even some guessing. A lot of surgeons struggle with it. Our goal was to make these procedures more precise.”

Precision, in this instance, is 5 millimeters (0.2 inches) of healthy tissue, which is the standard amount of cancerous tissue surgeons attempt to remove. This 5 millimeters of tissue – which is about as thick as a typical eraser at the end of a pencil or the thickness of a standard wedding ring – is enough to make sure that the cancerous cells are removed while limiting the damage done to the surrounding area.

The challenge is made more complicated by the fact that cancerous tumors can often have very visible horizontal borders on the edge, but less obvious vertical ones.

“The problem we heard from many of the surgeons we collaborate with is that it’s so hard to resection a tumor precisely,” Krieger added. “Surgeons bring a little ruler in and see the 5 [millimeter] distance and mark off the edges on the sides. But how deep to go—that’s so difficult.”

Even though pre-surgery preparation is extremely, painstakingly thorough, the 5-millimeter border represents a “blind zone”.

“The challenge is that surgeons do not have direct access to the tumor, due to surrounding tissue,” said doctoral student and team member Jiawei Ge. “They can see the surface of the tumor, but otherwise can only see the healthy tissue. The map is in the surgeon’s mind.”

To test the ASTR, the researchers turned to tongues. Tongue tumors are a well-positioned case for testing this new surgical system, due to their surface accessibility and current use in experimental surgery. While the condition is rare, you may have heard of it affecting some celebrities, such as Michael Douglas and Eddie Van Halen – the latter of which had unsuccessful surgery.

Using tissue from a pig’s tongue, the researchers were able to use ASTR to remove a tumor and exactly 5 millimeters of healthy tissue using its vacuum grasping and cutting tools. They carried out six consecutive resections and ASTR succeeded every time, not requiring any stoppage – the team was able to translate human guidance into robotic precision.

“The physician can supervise the robot and give pre-surgery inputs, then the robot does it step by step,” Krieger explained. “What we showed is that surgeons can get very good horizontal margins with the ruler, but on the depth margins our robot really shows improvement.”

The new robo-surgeon was based on a technology they developed for their Smart Tissue Autonomous Robot (STAR), which, in 2022, performed the first fully autonomous laparoscopic surgery – a procedure that connects two ends of an intestine.

The team developed STAR’s technical workings to create ASTR’s autonomous, dual-arm, vision-guided robotic system.

“We’ve sent the robot to make an incision before, but this is the first time we’ve done a bulk resection and taken a tumor out fully,” said Krieger. “That’s the big novelty here.”

The next step for ASTR is to operate on an internal organ, like a kidney. This will require different approaches and challenges to accessing the tumor. By combining ASTR’s precision with state-of-the-art imaging technologies, it is hoped that a new era of tumor resection may be on the horizon.

“They use robots a lot already in clinical practice, so this isn’t a huge paradigm shift,” Krieger concluded.

The study is published in IEEE Robotics and Automation Letters.