Scientists are developing a pill that could improve imaging techniques by illuminating only cancerous tumors. This could improve on current methods that can identify lumps but cannot conclusively determine whether they are cancerous.1
“There’s a lot of controversy right now about when patients should start screening for breast cancer,” said Greg Thurber, PhD, of the University of Michigan in Ann Arbor. “Screening can potentially catch the disease early in some patients, but false positives can lead to unnecessary, aggressive treatments in patients who don’t need them. We don’t know how to select the right patients to treat. Our work could help change that.”
Mammography is the current standard for breast cancer screening. If a suspicious lump is detected, biopsy is the next step; but even biopsies are not 100% conclusive. Finding a suspicious lump will often lead to treatment ranging from surgery to radiation or chemotherapy, which can take months and can cause serious side effects.
To better identify patients who do not really need treatment, Thurber’s team developed an oral pill containing an imaging agent that selectively binds to cancer cells or blood vessels that are unique to tumors. The imaging agent fluoresces under near-infrared light only when it attaches to its target. Light of near-infrared wavelengths can only detect tumors that are 1 to 2 centimeters deep, the elasticity off breast tissue should allow this technique to be paired with ultrasound in the same instrument so most cancers can be detected.
Testing in mice found that 50% to 60% of the agent gets absorbed into the bloodstream and binds specifically to cancer cells with little background noise in the image.
Thurber explained that the high image contrast should bode well for women with dense breasts whose mammograms are difficult to read. Thurber is also designing the agent to specifically seek out aggressive tumors, an approach that could distinguish them from slow-growing cancers such as ductal carcinoma in situ, a noninvasive breast cancer.
Currently, Thurber is coupling the probe with molecules to make it easier for human patients to absorb. He stated that predicting when his agent might go into human clinical trials is difficult. However, the dye is already used in Europe for other clinical applications, which could help speed the approval process in the United States.
1. Bhatnagar S, Dhingra K, Kelley W, et al. Disease screening pill for breast cancer: in vivo demonstration of an orally available near-infrared molecular imaging agent using mouse xenografts. Presentation at: 251st Annual Meeting of the American Chemical Society; March 10-14, 2016; San Diego, California. Abstract 187.