Story for The Georgia Straight, October 26-November 2, 2006

Island mammograms enter digital realmBy Star Weiss
Women who are concerned about their breast health might want to consider moving to Victoria. That's because Victoria General Hospital is the first place in the province to use digital mammography for breast cancer screening.

What this means for the average woman is that if you make an appointment for a routine screening, (which is recommended for all women after the age of 40) at Victoria General Hospital's Breast Imaging Department, your mammogram will be done using one of two state-of-the-art digital mammography machines. Thanks to the new equipment, plus an extensive make over of the unit in 2005, VGH is "totally in the digital world," says Louise Kallhood, a supervisor of breast imaging for the Vancouver Island Health Authority.

Digital mammography has been proven to be a more effective screening tool than the conventional film-based method for many women, especially those under 50, those with dense breast tissue, and those who are pre- or perimenopausal. Results from the Digital Mammographic Imaging Screening Trial, which were published in the October 2005 issue of The New England Journal of Medicine, confirmed that "the accuracy of digital mammography was significantly higher than that of film mammography" for the aforementioned groups, and at least as effective as conventional film-based exams for everyone else.

"Everybody knows that mammograms are going digital, says Dr. Stuart Silver, VIHA's clinical section head of breast imaging. "It's the new kid on the block. Film-screening mammography has gone as far as it will go. It's a mature technology, and this [digital] is at the beginning."

Silver stresses that conventional film-based mammography continues to be "an excellent service", and he strongly encourages all eligible women to have routine screenings regardless of whether the equipment is digital. (Since my own breast cancer was discovered by a regular mammogram in 2003, I second that motion.)

It's important to remember that breast self-examination is still a useful tool, and that even digital mammograms will miss some cancers. But the advantage of the technology for dense-breasted women is that the image can be digitally enhanced, so cancers can be discovered and diagnosed more accurately than with the conventional method. With digital mammography, there is less potential for dense breast tissue to hide a cancer, (a false negative) or for a benign abnormality to be misdiagnosed as cancer (a "false positive").

Silver says that digital imaging offers improved detection for many women and significantly less exposure to radiation. It also allows radiologists and doctors to immediately read, magnify and manipulate results and to electronically transmit images to their colleagues. For the woman undergoing a digital mammogram, the procedure is virtually the same as with the conventional machine. The digital technique may be "slightly more comfortable," says Kallhood, because the paddle that compresses the breast is contoured; on the other hand, the compression may last longer as the lab technician waits to check the computerized image.

At Victoria General Hospital's breast imaging department, the demand for digital mammography is growing. "We're a victim of our success," Silver says. "We can never keep up to the screenings." (The unit is now open evenings and Saturdays.)

Dr. Stuart Silver reads a digital mammogram on Vancouver Island, where new technology is providing improved breast-cancer detection for many women.

The Victoria centre is also the first public facility in B.C. to use a new software program known as Computer Aided Detection that highlights suspicious areas on mammograms and acts as a second set of eyes for radiologists, thereby eliminating the need to have two experts read the results.

The progressive steps being taken in Victoria don't come cheaply. Each digital machine cost around $500,000, the viewing station for radiologists was $150,000, and four high quality monitors totalled $50,000. Plus, the CAD program with film scanners was another $295,000. VIHA covered about 70% of the funding, with the remainder donated by the Greater Victoria Hospital Foundation.

For facilities with less funding, an alternative called computed radiography mammography has recently become available. Nanaimo Regional General Hospital just became the first in Canada to try the tool, which is a sort of compromise between purchasing digital-mammography equipment and staying with conventional film-based machines.

The advantage of computer radiography is that it is compatible with conventional mammography machines, and by substituting electronic imaging plates for film cassettes, the resulting digital image is as accurate as any taken on a fully digital machine, says Heather Gibson, director of medical imaging for VIHA. The cost to upgrade to CR mammography is under $200,000. On the downside, using CR is a more complicated process, which still involves inserting and removing a cassette from the mammogram machine; then inserting the cassette into a scanner to process, and finally viewing the image in digital format in another room. Since CR is more time-consuming than going fully digital, it's considered more suitable for clinics with lower volume.

According to the Mammography Screening Program of BC, regular exams for women 40 to 79 have been shown to reduce breast-cancer mortality rate by 24 percent. With digital screening, we can further reduce that rate, and even more women will be able to beat the disease.

What about Vancouver?

By Star Weiss

The only digital-mammography machine in B.C. outside Victoria is located at the BC Cancer Agency in Vancouver. According to Dr. Patricia Hassell, a radiologist in diagnostic imaging at the BCCA, that machine is underutilized. It is presently used as a diagnostic follow-up for patients with breast cancer or abnormal mammograms, and for high risk patients. At the moment, all routine screening mammograms in Vancouver are film-based. Hassell said she believes there is "no reason we can't have a screening centre here at the agency" and suggests the digital machine could be used for that purpose on weekends or evenings. She thinks a study that would look at the use of the machine for screening women with dense breasts or who have a history of breast cancer would be a good starting point. "Mammography is not perfect," Hassell says, "but it's still the best tool we have."