In a new study, researchers have described a new technique for determining the "leakiness" of tumour blood vessels using a simple digital mammography unit, which can predict the results of breast cancer chemotherapy.
Successful chemotherapy depends on the ability of anticancer drugs to escape from the bloodstream through the leaky blood vessels that often surround tumours.
For the study, the researchers designed nanometre-sized capsules containing a contrast agent, which could only leak into tumours with blood vessels that were growing and therefore leaky.
The digital mammography-based quantification of "leakiness" is linked to the ability of a clinically approved chemotherapy agent to enter the tumour, enabling the researchers to predict the agent's therapeutic efficacy.
"We developed a quantitative way to measure the leakiness of the blood vessels, which is directly linked to the amount of drug that gets to the cancer and in turn determines effectiveness," said Ravi Bellamkonda, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.
He added: "By simply measuring how much contrast agent reaches the tumor, we can predict how much of a clinically approved chemotherapeutic will reach the tumor, allowing physicians to personalize the dose and predict effectiveness."
At times one chemotherapy drug may not be effective in treating the tumour, but the new technique allows oncologists to investigate other drugs sooner since they know the drug is reaching the tumour.
Currently studies are underway to determine if mammography can predict the optimal dose of a wide range of breast cancer chemotherapeutics.
For the study, a long-circulating nanometer-scale liposomal capsule, filled with iodinated contrast agent, was injected into rats with six-day-old breast cancer tumours.
For the next three days, the researchers collected digital mammography images of the animals, and compared the pre- and post-injection grayscale intensity values to study the dynamics of how the contrast agent accumulated in the tumour over time.
"During the three-day time course, some tumors exhibited a rapid and significant increase in image brightness, meaning the contrast agent was accumulating in the tumor, whereas other tumors showed a slow and low increase," said Bellamkonda.
Although the brightness of the tumours in the images changed significantly, researchers saw no variations in non-tumour areas or in the tumours of animals that had not receive the contrast agent.
Immediately after the imaging was completed, and the leakiness of each individual cancer vessel was quantified, the animals were intravenously injected with a clinically approved chemotherapy drug, liposomal doxorubicin.
It was found that the chemotherapeutic drug slowed the progress of the tumour.
Now the scientists want to probe whether the leakiness of tumour vasculature represents a parameter that is useful for clinical diagnosis or tumour characterization.
"We want to study the molecular basis for blood vessel leakiness. We want to understand why there is variation in leakiness and chemotherapy effectiveness among individuals with tumors of the same type, size and stage," said Bellamkonda.
The study has been published in the latest issue of the journal Radiology.