A new imaging system under development uses red and near-infrared light to identify breast cancer patients who are likely to respond to chemotherapy, possibly as early as two weeks after beginning treatment, according to a pilot study.
The non-invasive method tracks blood flow dynamics during a simple breath hold to predict patient responses.
“There is currently no method that can predict treatment outcome of chemotherapy early on in treatment, so this is a major advance,” Andreas Hielscher, the study’s co-lead author, said in a press release. Hielscher is a professor of biomedical engineering and electrical engineering at Columbia Engineering and professor of radiology at Columbia University Irving Medical Center.
The study, “Dynamic diffuse optical tomography for monitoring neoadjuvant chemotherapy in breast cancer patients,” were published in the journal Radiology.
With the new dynamic optical system, researchers generate 3-D images of both breasts simultaneously and are able to monitor changes in blood flow, and how the blood interacts with breast tumors.
“This helps us distinguish malignant from healthy tissue and tells us how the tumor is responding to chemotherapy earlier than other imaging techniques can,” said Hielscher, who is also a member of the Breast Cancer Program at the Herbert Irving Comprehensive Cancer Center, NewYork-Presbyterian/Columbia University Irving Medical Center.
Breast cancer patients who have an invasive, inoperable tumor receive neoadjuvant chemotherapy for about six months. The therapy is used before surgery to kill active cancer cells.
While this approach reduces the risk of cancer recurrence, fewer than half of the women treated with neoadjuvant chemotherapy achieve a complete response, or complete tumor eradication.
“Patients who respond to neoadjuvant chemotherapy have better outcomes than those who do not, so determining early in treatment who is going to be more likely to have a complete response is important,” said Dawn Hershman, MD, co-leader of the study and leader of the Breast Cancer Program at the Herbert Irving Comprehensive Cancer Center at NewYork-Presbyterian/Columbia.
“If we know early that a patient is not going to respond to the treatment they are getting, it may be possible to change treatment and avoid side effects,” she said.
Looking at blood flow in the breasts could give researchers a clue as to who is responding to neoadjuvant chemotherapy. This is because blood vessels look different in healthy tissue versus tumors. While healthy tissues have organized blood vessels and blood flows freely, tumors have a denser network of blood vessels, meaning the blood flow is delayed and gets soaked in the tumor.
Chemotherapy also affects blood vessels inside the tumor, and because blood absorbs light quite strongly, researchers hypothesized they could use their optical system to measure changes in the tumor’s vasculature.
They analyzed images from 34 patients acquired between June 2011 and March 2016. Contrary to mammograms, their optical system required breasts to be placed comfortably without squeezing.
Images were captured in two separate moments — first, during a breath hold of at least 15 seconds, allowing the team to capture blood inflow through large vessels (arteries), and then after the breath was released, capturing how the blood flowed out of the veins into the breasts.
The procedure was conducted before the start of chemotherapy, and again two weeks after patients began the treatment. Researchers repeated the exam after five months of chemotherapy.
Blood inflow and outflow could be used as a potential readout to identify patients how patients will respond to chemotherapy. The rate of blood outflow correctly identified 92.3 percent of responders, while the early increase in blood concentration inside tumor vessels identified 90.5 percent of non-responders.
“If we can confirm these results in the larger study that we are planning to begin soon, this imaging system may allow us to personalize breast cancer treatment and offer the treatment that is most likely to benefit individual patients,” said Hershman, who is also a professor of medicine and epidemiology at Columbia University Irving Medical Center.
Researchers are also testing the predictive power of other imaging strategies, including magnetic resonance imaging (MRI), X-ray imaging, and ultrasound, but none are as promising as the red and near-infrared optical system.
“X-ray imaging uses damaging radiation and so is not well-suited for treatment monitoring, which requires imaging sessions every two to three weeks,” Hershman said. “MRIs are expensive and take a long time, from 30-90 minutes, to perform. Because our system takes images in less than 10 minutes and uses harmless light, it can be performed more frequently than MRI.”
Researchers are currently refining the imaging system, and plan to test it in a larger, multicenter clinical trial. If results are positive, they hope to have the technology available on the market in three to five years.
“If confirmed in a prospective study with a larger cohort, dynamic optical imaging parameters identified in this pilot study may be used for predicting treatment response in patients with breast cancer undergoing several months of neoadjuvant chemotherapy, as early as 2 weeks after treatment initiation,” the study concluded.
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