By Caitlund Davidson, Health Promotion and Communications Planner, Thunder Bay Regional Health Sciences Centre
Breast cancer is the most commonly diagnosed cancer among women in Ontario. The good news: the five-year breast cancer survival rate is 88%, according to statistics from Ontario Health – Cancer Care Ontario. This means 88% of women diagnosed with breast cancer will survive for five years after their diagnosis. Improvements in the survival rate can be attributed to increases in the number of women attending routine breast screening and improvements in treatment.
Routine breast cancer screening did not exist until the 1980s. When most people think of breast screening, they immediately think of a mammogram. Mammography is the gold standard screening test used today to detect breast cancers early, when they are small and less likely to have spread. However, the mammogram that many of us are familiar with today is very different from when breast imaging first became available.
The first device used specifically for mammography was introduced in 1966. It was essentially a tripod supporting a special x-ray camera. Prior to this, the imaging process was tedious and slow. The patient would have to stand up and then lie down to get images from two different angles, which only allowed four to five patients to be imaged per day. This new model allowed images to be taken with the patient in a sitting or standing position, which improved efficiency, but imaging was not done unless the patient had a palpable mass.
Next came xeromammography in the early 1970s, which provided better image quality and allowed physicians to see the chest and ribs. There were several downsides to xeromammography, including the higher dose of radiation compared to other imaging methods, manual compression of the breast resulting in inconsistent images, and the blue dye that was used for paper images created a mess.
Throughout the 1980s, progress was made to improve the image quality by transitioning from paper images to film and compression became an automated process.
The late 1980s and early 1990s brought the acceptance of mammography as the first line of defense against breast cancer. Greater routine participation in mammography screening began, especially after the introduction of Ontario’s organized Breast Screening Program (OBSP) in 1990. The OBSP continues to be available for average risk women aged 50–74, with breast screening being done with a mammogram every two years. There is also a high-risk OBSP for women between the ages of 30 and 69 who meet the eligibility criteria.
Organized screening has important advantages, including systematized recruitment, recall, and follow-up, ongoing quality assurance, quality control, and evaluation. Today, breast screening is more easily accessible, with over 230 OBSP screening sites in Ontario, including five locations in Northwestern Ontario and the Screen for Life Coach.
“It was unlikely, in the early days of mammography, that people would have thought mammography units could be placed on a bus and moved from community to community to do breast cancer screening,” says Tarja Heiskanen, manager of screening and assessment services at the Thunder Bay Regional Health Sciences Centre. “Since 1992, there has been a mobile cancer screening coach active in Northwestern Ontario. We’ve come a long way with imaging technology and our understanding of the importance of early detection.”
At the turn of the decade, we were introduced to digital mammography. The process remained the same for the patients but images were read on computers rather than film. Further advances in technology resulted in the development of 3D imaging. While 2D imaging acquires images of each breast, 3D captures up to 30 images per breast and can find about 30% more cancers. Modern mammography has made it possible for health care providers to detect and treat cancer earlier, with less exposure to radiation than before.
According to the 2020 Canadian Cancer Statistics report, after peaking in 1986 (42.7 per 100,000), the mortality rate for breast cancer has continued to fall year after year, dropping to an estimated 22.0 per 100,000 in 2020. As additional technological innovations are achieved and breast imaging radiologists continue to advance in their expertise, mammography is expected to remain a key player in early detection efforts.
For more information on breast cancer screening, visit cancercareontario.ca/en/types-of-cancer/breast-cancer/screening