Half of all Americans will be diagnosed at some point in their lives with cancer, the number two killer in the United States. One of the most common types, especially among women, is breast cancer. According to the National Cancer Institute, 192,370 women will be diagnosed with breast cancer in 2009, and more than 40,000 women will die from the disease this year alone.
One of the professions at the frontlines in the battle against breast cancer is medical physics. Medical physicists help to develop new imaging technologies and improve existing ones. They devise new therapeutic techniques, and they create methods to assess the safety and effectiveness of treatments that are already in use.
Included below are highlights of a few of the presentations related to breast cancer research at the 51st annual meeting of the American Association of Physicists in Medicine (AAPM), which takes place from July 26 - 30 in Anaheim, CA.
A NEW SCREENING TOOL FOR BREAST CANCER
Mammography has proven to be very effective at lowering mortality related to breast cancer, but it does not work equally well in all women. It frequently misses tumors that are there at the time of screening -- particularly in women who have dense breast tissue that can hide tumors from doctors. The National Cancer Institute reports that mammograms miss up to 20 percent of breast cancers that are present at the time of screening. Doctors often recommend women with dense breasts undergo magnetic resonance imaging (MRI), which is more expensive but better at detecting cancer in dense tissue.
Now doctors at the Mayo Clinic in Rochester, MN have developed a less expensive "molecular imaging" technique for detecting cancer in dense breast tissue using radioactive tracers. In Anaheim, Michael O'Connor, a professor of radiologic physics at Mayo, will describe the science behind this technique as well as the latest results from ongoing clinical trials, including one involving 1,000 women who all received the molecular imaging.
The technique has shown to be highly sensitive at detecting breast cancer, says O'Connor. The key now is to make sure that the doses administered are as low as possible -- equivalent to what you would receive in a mammogram. A study supported by the Susan G. Komen Foundation will begin enrolling 1,000 women in a few months to see how effective the technique is with low-dose formulations.
The talk, "Molecular Imaging of the Breast" is at 10:30 a.m. on Tuesday, July 28 in room 210A. See: http://www.aapm.org/meetings/09AM/PRAbs.asp?mid=42&aid=11931
When women have routine mammograms to screen for breast cancer, their doctors and health care providers use X-rays to detect tumor masses. This is an extremely safe way of detecting breast cancer, and the National Cancer Institute recommends that all women over the age of 40 should have mammograms every one to two years. The benefits of doing so are enormous because mammography is effective at detecting breast cancer early, when it is most treatable.
Because mammography uses X-rays, however, there is an extremely small but finite risk those X-rays will damage DNA and cause secondary malignancies months or years later. Even though this risk is very small, more than 100 million women have mammograms every year, and a small number of them will be at risk for these secondary cancers. Minimizing the radiation from mammography is a way of mitigating this risk.
A few years ago, Mats Danielsson was a physicist at the European Organization for Nuclear Research (CERN), where scientists have access to very efficient and extremely sensitive detectors that can detect single photons -- a necessity for modern particle physics experiments. He thought that this same technology might allow doctors to lower the dose of X-rays women undergoing mammography receive. So Danielsson, who is now a professor at the Royal Institute of Technology in Sweden, founded a company that built such sensitive detectors. Clinical trials in Europe a couple years ago concluded that the detectors could effectively lower radiation doses by half while still diagnosing cancers effectively.
These detectors are now installed in some 150 clinical centers in 15 different countries, and work is ongoing in order to win approval by the Food and Drug Administration, which regulates medical devices in the Unites States. In Anaheim, Danielsson will present his latest data on how the detectors can help to resolve different tissues in the breast. He and his colleagues are in the midst of a large, multicenter clinical trial that seeks to get information on cancers by analyzing the energy of the X-rays.
The talk, "Photon Counting Detectors for Mammography" is at 1:30 p.m. on Monday, July 27 in room 210A. See: http://www.aapm.org/meetings/09AM/PRAbs.asp?mid=42&aid=11927
BREAST CT SCANNERS FOR THERAPY
Since 2004, a group of researchers at the University of California, Davis led by John M. Boone, Professor and Vice Chair of Radiology and Professor of Biomedical Engineering, has been developing a new technology for diagnosing breast cancer in women that promises to be more comfortable than conventional mammography but just as safe.
The discomfort of a mammogram can drive some women to avoid the valuable screening, occasionally with dire consequences. But the new procedure, based on computed tomography (CT), promises to take the pain out of breast cancer detection. In the cone beam breast CT scanner, a woman lies face down on a special table with one breast suspended through an opening. A CT scanner rotates around the breast, collecting data that are reconstructed into a three-dimensional image. The total dose of radiation is the same as in a conventional mammogram.
Boone and his colleagues have scanned more than 200 women with their prototype scanner. Now they are teaming up with radiation oncologists to explore whether the same system can be used to treat breast cancer. By carefully rotating the CT cone beam around the breast, they can deliver a lethal dose of X-rays to cancer cells inside a tumor while sparing healthy tissue. So far, they have measured dose distribution and performed simulations to show the feasibility of such a system, which Boone will describe in Anaheim.
The talk, "Breast CT as a Platform for Image Guided Therapies of Breast Cancer" is at 4:55 p.m. on Tuesday, July 28 in room 303A. See: http://www.aapm.org/meetings/09AM/PRAbs.asp?mid=42&aid=11896
UPDATE ON DIGITAL MAMMOGRAPHY
In the last few years, digital mammography has become a popular alternative to conventional film-screen mammography systems. According to Kalpana Kanal, an assistant professor of radiology at the University of Washington, about half of all mammography systems in the United States today are digital -- up from about a third just a year ago.
Though digital systems are about four times more expensive, they offer significant advantages over film, says Kanal. Moreover, a 2005 article published in the New England Journal of Medicine based on the DMIST study of 50,000 women compared digital with film mammography and showed that the overall diagnostic accuracy as a means of screening is similar for both technologies. However, digital mammography is more accurate for women under the age of 50, women with dense breasts, and premenopausal and perimenopausal women.
In Anaheim, Kanal will give an overview of the various digital mammography systems available in the United States and discuss their advantages and disadvantages and the benefits of going digital.
The talk, "Digital Mammography Update: Design and Characteristics of Current Systems" is at 8:30 a.m. on Monday, July 27 in room 303A. See: http://www.aapm.org/meetings/09AM/PRAbs.asp?mid=42&aid=11958
American Institute of Physics