Filters: a new way of detecting cancer

Brittney Bomnin // Photo Editor
Brittney Bomnin // Photo Editor
Brittney Bomnin // Photo Editor

From making coffee to keeping swimming pools clean, filters are constantly being used in everyday life.

However, two researchers from the University of Miami’s Miller School of Medicine, Dr. Richard J. Cote and Dr. Ram Datar, who are co-directors of the biomedical nanoscience program, are now using filtration to detect cancer cells in a breakthrough test using nanotechnology.

Although there are other technologies and methods used to detect circulating tumor cells in the blood of cancer patients, they involve multiple steps, require a large amount of blood and are not very sensitive. Since 1999, these doctors  have been working to try to change this.

With assistance from UM graduate student Anthony Williams, they eventually created a microfiltration test where cancer cells, which are slightly larger than regular blood cells, get trapped in the fine filters that they pass through.

“These are very very subtle differences but they’re real, and they’re consistent, and we have taken advantage of this to create these devices which can actually catch these tumor cells, very very rare tumor cells in large quantities of blood,” Cote said.

Aside from using this test to detect cancer cells early on, it is also used to test present cancer cells.

“This is actually to see if the cells are there and how many are there,” Datar said.

By analyzing the cancer cell count over time, they are able to conclude whether the patient’s current cancer treatment is working and the rate at which it works.

The test is given over a certain period of time to patients in the Southwest Oncology Group, a cancer clinical trials cooperative group in the U.S. The blood is sent to Cote and Datar’s lab overnight from different institutes across the country.

“We see patients from Arizona, from Colorado, from Texas, all the way from Oregon and some patients in Alaska,” Williams said.

To identify the cancer of the trapped cells, they use nano-crystal quantum dots made by dissolving metal oxides. The cancerous cells are then colored in different fluorescent shades depending on their sizes. The sizes they deal with do vary, but are usually around 10 to 15 nanometers.

“Consider a grain of rice to be one millimeter, which is a million times bigger than a nanometer— and so that’s the kind of scale were talking about,” Cote said.

From filtering the blood to placing the cells on the slide, the entire microfiltration test takes only a few minutes. Since it is based on cell size, a broad range of cancers can be caught. So far, they have been testing for four types: breast, prostate, lung and bladder.

“We will catch every cancer type so we can do our analysis later based on what type of cancer we want to look at,” Williams said.

Their research and testing is supported through grant funding. Recently, the National Institute of Health awarded them a $3 million grant for their first clinical trial on microfiltration and the capturing of CTCs.

They have also received a $16 million grant to create a center at UM for nanotechnology cancer research in collaboration with colleagues at the University of Southern California, Oakridge National Labs and the California Institute of Technology.

The test is expected to be approved by the FDA in three to five years.

“It’s a very sensitive and very powerful technique to detect tumor cells in the blood and it has enormous implications for making the diagnosis of cancer,” Cote said.