Interesting idea, I hope it pans out.

Now, researchers at Georgia Tech are studying a new weapon in the war against ovarian cancer by using magnetic nanoparticles engineered to attach to cancer cells circulating in the body.
“If we can target those magnetic nanoparticles to ovarian cancer cells, they’ll attach to the free-flowing cancer cells, and then, in a magnetic field, we can sweep all of the cancer cells out,” John Mcdonald, Ph.D., a professor of biology at Georgia Tech, explained.
Like dialysis, fluid is circulated through and out of the patient’s abdomen and into an external chamber where tiny magnetic nanoparticles grab the cancer cells. The cleaned fluid is returned to the body
“To explain how many nanoparticles you might use for a treatment, in about a gram of material, we’re talking literally billions and billions of nanoparticles," Kenneth Scarberry, Ph.D. a post-doctoral fellow in nanochemistry at Georgia Tech, said.
It’s an experimental technique that could one day improve survival.