A new analysis, published in Academic Radiology, suggests that almost a quarter of interval breast cancers could have been caught earlier than they were.
The term “interval breast cancer” refers to cancers that present themselves or are detected within about 12 months after a mammogram that came back normal. They are considered “interval” cancers because they show up within the one-year interval that normally occurs between scheduled mammograms.
Some reasons why interval cancers are not caught at initial mammograms include clinician oversight and fast growth. Until recently, it wasn’t known roughly how many of these cancer cases were not caught because they were simply too small or nonexistent at the time of the initial mammogram and how many were not caught because of oversight issues.
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For this study, researchers identified 1,010 cases of interval breast cancer diagnosed between 2004 and 2016 as part of the BreastScreen Norway program. The average time between exams for these women was 14 months, and their average age at diagnosis was 61.
The researchers classified each case as “true” (no findings on prior screenings), “occult” (no findings at screening or diagnosis), “minimal signs” (minor, non-specific findings), or “missed” (obvious findings). The first two groups made up about 48 percent of the cases studied, while 28 percent showed minimal signs. The “missed” group made up nearly a quarter of the cases.
After examining the cases, the researchers deemed 246 of the cases to have been missed at the initial screening, despite obvious findings that should have led to extra screening and a diagnosis. That’s about 24% of cases that could have been viewed on a previous mammogram but weren’t diagnosed until later.
The researchers believe more breast cancer cases could be caught earlier by shortening the times between screenings or implementing new types of screening techniques to supplement existing ones. They also hope, however, that training for radiologists can be improved to help them catch cases of cancer early more often.
“Education, including self-assessment and training schemes, and participation in reviews could be ways to improve the screen reader’s sensitivity to more subtle findings,” wrote Tone Hovda, MD, of the Department of Radiology at Vestre Viken Hospital Trust in Drammen, Norway, and colleagues. “These strategies may also improve the radiologists’ perception and interpretation and increase their awareness of possible pitfalls.”
Dr. Hovda says secondary readings of mammograms, optimized image quality, and improved patient positioning could help reduce these “missed” cases.
“During the past years, artificial intelligence based on deep convolutional neural networks shows promising results in breast diagnostics and screening,” the team wrote. “And if AI in the future demonstrates the ability to detect abnormalities in images not perceived by radiologists, or not even detectable by the human eye, it may be possible to lower the interval cancer rate.”
This is just another reason why you shouldn’t be afraid to get a second opinion if you feel like something is not quite right in your body. It’s important to get to know your breasts and be aware of the potential signs of breast cancer (which can include a lot more than just lumps) so that you can advocate for yourself if something goes wrong.
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