AAPM: Gold nanoparticles could strangle tumors

Microscopic gold particles could multiply the effectiveness of standard cancer radiation therapy by acting as tiny missiles that destroy blood vessels feeding cancerous tumors. Early research about this method, which could shorten cancer treatment and make it more effective, is being presented at the 2011 Joint Meeting of the American Association of Physicists in Medicine (AAPM) and Canadian Organization of Medical Physicists (COMP).

The study focused on the combination of gold nanoparticles and brachytherapy. Supplementing brachytherapy with gold nanoparticles would add a new cancer-killing mechanism that collapses the blood vessels, effectively strangling the tumor, the research suggested.

“The idea is to deliver a one-two punch to the cancer: bombard the tumor with standard radiation therapy while also attacking its blood supply,” the study's lead author Ross I. Berbeco, PhD, a staff physicist at Brigham and Women’s Hospital and Dana-Farber Cancer Institute, both located in Boston, said in an interview.

The concept could provide a synergetic effect by enhancing efficacy of cancer treatments while reducing some of the risks of treatment. While the entire tumor volume receives a standard dose of radiation, the vasculature is boosted with gold nanoparticles.

“Although we have also shown that the concept may work for external beam radiation therapy, brachytherapy is particularly attractive for this idea due to the way this low-energy type of radiation interacts with the gold,” Berbeco continued.

The research suggested that gold nanoparticles may act as a vascular disrupting agent (VDA), cutting off the flow of blood to the tumor by destroying the cells that line tumor-feeding blood vessels. Most vascular disrupting agents are delivered through chemotherapy, and studies have shown supplementing radiation with VDA chemotherapy may improve cancer treatment. The Brigham research indicated that the gold nanoparticles could destroy the blood vessels at the same time radiation therapy is administered.

Another plus of the approach is the low risk of side effects. The gold nanoparticles are dormant and benign in the body until bombarded with radiation, so the treatment is minimally toxic to normal tissues. “We could improve therapy without increasing the risk of side effects,” Berbeco stated.

To test their concept, researchers performed a computer simulation of gold nanoparticles in a tumor blood vessel cell, where brachytherapy seeds had been placed nearby. Results showed the gold nanoparticles boosted the radiation dose to the blood vessel cells.

“This is an exciting opportunity for a low-risk, high-reward procedure that could improve cancer care,” said study co-author Wilfred F. Ngwa, PhD, research fellow at Brigham and Women’s Hospital and Dana-Farber Cancer Institute.

The researchers are beginning in vitro experiments and preliminary results have confirmed the theoretical findings, shared Berbeco.