Health minister Adrian Dix’s announcement that B.C. will be the first province to notify women if they have dense breasts after screening mammograms, and may therefore be at higher risk of cancer, has led to some concerns and confusion about how the information should be used.
Advocates have long pressed cancer authorities and governments to share such information with women. It has always been collected by screening programs, and dense breasts are one of a number of factors raising the risk for breast cancer.
In B.C., dense breasts are fairly common — 106,000 women out of 255,000 screened in 2017 had the highest levels of density — and while more knowledge in the hands of patients is always empowering, there are many questions about how the health care system might cope with a deluge of requests from women who may demand supplementary testing along with their mammograms, or when they discover a so-called interval lump weeks or months after their routine, normal, mammograms.
Supplementary tests include ultrasounds, MRI and digital tomography imaging, all of which may be more effective at finding tumours in dense (fibrous, glandular) tissue, as opposed to more fatty tissue.
On mammogram X-rays, tumours appear as white masses, but so does dense tissue. Therefore, dense tissue can obscure or mask tumours, which is why there are higher rates of advanced breast cancers diagnosed in the intervals between screening mammograms among women with dense breasts.
About 3,500 women in B.C. are diagnosed with breast cancer each year. It is the most common cancer in women. On it own, breast density is not reliable as a sole predictor of breast cancer risk but among women aged 40 to 74, those with the highest density have about double the risk of being diagnosed with breast cancer in the intervals between their screening mammograms.
Other risk factors include family history, menopausal history, reproductive factors and body mass index.
Dr. Paula Gordon, the radiologist who is medical director of the Sadie Diamond Breast Program at B.C. Women’s Hospital, said tumours found in the interval periods between mammograms are often larger and often have already spread to the lymph nodes. Such patients require more radical treatment and face a poorer prognosis.
“These women are more likely to need mastectomy (rather than lumpectomy), need axillary (lymph node) dissection rather than just sentinel node biopsy, which has a higher risk of lymphedema, and are more likely to need chemotherapy.”
Based on an American model, an additional three to four cancers per thousand women screened are expected to be detected as a result of breast density information being known and used with the most ideal imaging techniques like ultrasound, she said.
“This might sound like a low number,” Gordon said, “but that’s how many we find on mammograms, so adding ultrasound doubles the cancer (detection) rate. And, unlike mammograms which detect both invasive and non-invasive cancer, ultrasound finds mostly small, invasive, node-negative cancers.”
When he made the announcement late last week, Dix said if supplementary screening is “felt to be medically necessary” by a woman and her physician, then it will be publicly funded and covered by the Medical Services Plan.
But breast cancer advocates are confused about who will be entitled to get such publicly funded testing on demand. In the Canadian health care system, the term “medically necessary” is often open to interpretation.
Currently, there is a fee radiologists can bill for diagnostic but not screening ultrasounds. Gordon, who also works at the private radiology clinic XRay 505, wonders how the latter will be billed to MSP, and if the health care system is overwhelmed by requests for supplementary testing, how the deluge will be managed.
“Who is going to do the ultrasound? Currently, XRay 505 is the only clinic with extensive expertise in screening ultrasounds. And that expertise is essential to minimize false alarms.”
The clinic charges women with dense breasts, or others who want supplementary breast cancer screening, between $100 and $250 for screening ultrasounds.
Laura Heinze, a spokeswoman for the health minister, said Monday that a medically necessary supplemental ultrasound would be one that is ordered “after the patient’s physician reviews the mammogram and speaks with the patient about any other risks such as familial history, symptoms, or any concerns that were found on the mammogram that require additional testing.
“Should a physician feel that a supplementary ultrasound is warranted, it would be fully covered under MSP.”
Heinze said patients can pay privately for ultrasounds if they are getting them “simply for peace of mind, not because it is medically required.”
Gordon said she worries that a lot of family doctors don’t have enough information to discuss the implications of breast density with patients.
“So I fear that some doctors will try to dissuade their patients from having supplementary screening,”
Dix said information packets are being prepared for family doctors, who will have them in January 2019.
Dr. Colin Mar, medical director of the B.C. cancer screening mammography program, said women have a right to know their density information, and there is planning underway to determine the best way to share it but he acknowledged that the cancer agency is not planning to recommend supplementary testing for women with dense breasts for the time being because there isn’t enough scientific evidence to support a broad recommendation.
That means if women want further tests, they will have to navigate that outside the screening program.
Mar said the issue of what services are paid for is a matter for government, but the cancer agency is keen to give input if asked.
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