A Telling Test

“This test is only for patients who have been diagnosed with ductal carcinoma in situ (DCIS), which is basically that earliest form of breast cancer that is considered a noninvasive form of breast cancer,” MacKenzi Smith, a Physician Assistant-Certified (PA-C) at the Avera Cancer Institute in Yankton, told the Press & Dakotan. “We refer to it as ‘stage 0,’”

The test is performed on the removed cancerous tissue, she said.  

“There are a few different ways you can test it,” Smith said. “You can test it with biopsy tissue, or we usually test the post-surgical lumpectomy specimen.”

The test examines certain biomarkers and biological pathways, as well as some other risk factors that can contribute to progression of the breast cancer, including patient age, size of lump and whether its margins were free. The resulting calculation helps patients and their doctors gauge the 10-year risk associated with that specific cancer, she said.  

“It scores it between 0 and 10,” Smith said. “They consider between 0 and 3 as low. With those low-risk scores, we consider your risk low for recurrence of the disease, whether it be the same noninvasive cancer that you were previously diagnosed with, or it (becoming) something invasive.”  

DCISionRT gives multiple scores.

First, it shows the patient’s risk of developing DCIS again over the next 10 years with breast conserving surgery alone, and the risk associated with surgery and additional radiation therapy, she said.

In the case of a low score, doctors would predict little benefit from added radiation therapy, she said.

“We would consider that lumpectomy, that surgery, adequate, and that if we were to add radiation, it wouldn’t give you any more benefit to decrease in your risk your percentage for risk of recurrence in a 10-year period,” Smith said.

A high score would indicate that radiation therapy would benefit the patient over the long term, she said.

“In this particular example that I have in front of me, the elevated DCISionRT score was 6.8, so their risk of recurrent breast cancer with surgery alone for the 10 years was 28% risk,” Smith said. “If you were to give radiation, it would decrease this particular patient to 9%. That’s a pretty big percentage difference.”

The test also gives scores regarding the likelihood of the cancer mutating into something more invasive over the same time span, both with and without radiation therapy.

“The 10-year risk for it turning into an invasive breast cancer with only surgery, in this particular one, was 20%, but with surgery plus radiation, it decreased it to 7%,” she said.

The test, which has been available at Avera for about a year, offers insight not previously available to doctors.

“Sometimes, we get surprised,” Smith said. “Where we (might have) thought radiation would be beneficial, it comes back only a couple of percentage points of benefit.”

Radiation therapy comes with its own host of risks and side effects that may not be of benefit, she said.

“The results are patient-dependent, and the patient always has the final decision as far as their treatment care,” Smith said.