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4:04 PM Thu, Nov. 15th

In the Pink: Looking at cancer DNA to determine what type of chemotherapy will work best

A scientist at work at Caris Life Sciences, which tests cancer tissue samples to determine what form of chemotherapy works best to combat a patient’s cancer.

Courtesy Caris Life Sciences

A scientist at work at Caris Life Sciences, which tests cancer tissue samples to determine what form of chemotherapy works best to combat a patient’s cancer.

Chemotherapy (chemo) was first used to treat cancer in the 1950s.

Since then, hundreds of chemo drugs have been developed, of which more than 100 are still used, according to the American Cancer Society.

Simply put, chemo is the use of strong drugs to treat cancer.

Though each chemo drug is designed to kill certain types of cancer cells, figuring out exactly which one or combo of these 100 plus drugs to use on a patient is not always a simple task.

Depending on the type of cancer and the stage of its development, Dr. Robert Zieve, Medical Director and Coordinator of Partners in Integrative Cancer Therapies in Prescott, will sometimes recommend that his patients send a sample of their cancerous tissue to Caris Life Sciences in Phoenix.

Caris is a biotechnology company that specializes in cancer diagnostics. It’s not the only one of its kind in the country, but it’s one that Zieve has had a positive experience working with.

“It helps us discover what, if any, chemo drugs will help a patient with a more serious cancer,” Zieve said.

The company specifically focuses on helping cancer patients who have aggressive, late-stage, or metastatic tumors that have gone beyond traditional guideline-based recommendations for standard cancer treatments.

One way they do this is by testing cancerous tumor tissue to sequence its DNA to look for mutations that may be driving the tumor’s growth.

“Sometimes different tumor mutations are associated with the efficacy of different drugs,” said David Spetzler, president and chief scientific officer of Caris Life Sciences.

Another test they’ll use is looking at differential protein expressions.

“Often tumors will express protein in different ways than healthy tissue does,” Spetzler said. “Sometimes that differential expression helps guide decisions around which chemotherapies are more or less efficacious than other therapies.”

Using such tests, Spetzler said they’re able to make good recommendations on about 25-to-30 of the most common chemo drugs in use today.

“We’re basically able to identify a list of potentially good drugs in about 95 percent of patients and we’re able to identify potentially bad drugs in about 97 percent of patients,” Spetzler said.

While the testing isn’t cheap, Zieve said he’s found it to be affordable for most patients with insurance, with a deductible, and covered completely by Medicare.