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Confused about breast cancer screening? Our experts weigh in

woman asks her doctor about screening for cancer

Currently in Ontario, the Ontario Breast Screening Program recommends that most women ages 50 to 74 be screened for breast cancer every 2 years with mammography. For high-risk women ages 30-69, the OBSP recommends yearly screening.

New guidelines for breast cancer screening of average risk women were released last week by the Canadian Taskforce for Preventative Health Care.

The guidelines were met with some debate amongst the online breast cancer community, leaving some people (ie. me) feeling a bit confused about who should be screened and when.

In this series, three of our experts weigh in on the new guidelines and share their key thoughts about mammogram screening. Over the coming weeks, we may post more thoughts, so please check back.


Dr. Martin Yaffe

Dr. Martin Yaffe:

The Breast Cancer Screening Researcher

“Screening works for women aged 40-74. It saves lives. But to be screened or not is always your decision.”

Read Dr. Yaffe's full thoughts

There’s a substantial benefit to taking part in breast cancer screening. Screening programs reduce deaths from breast cancer, and reduce the need for harsh treatments because the cancer is typically caught it its earlier stages.

Tons of recent research has looked into modern screening technology and modern treatment methods. That research has unanimously found an overall reduction in breast cancer deaths in women who are screened for breast cancer, including women aged 40-49. Recent Canadian and worldwide data shows about 40-50% reduced breast cancer deaths — about three times better than what Canadian Task Force has suggested.

I like to think of screening programs like a smoke detector in your home. You install a smoke detector in the hope that it will notify you quickly if your house is on fire. You also install it in the hope that will never happen. And really, the chances of a fire in your home are rather slim. Most people will never have a fire in their home; everyone has smoke detectors, just in case.

The same goes for breast cancer screening. Most women won’t have breast cancer. But for those who do, the screening can detect it earlier, when it could save your life and also there’s less of a need for harsh and toxic therapies.

The new guidelines talk a lot about the harms of screening – false positives and overdiagnosis. I disagree with these words. And I think there are things we can do to better reduce these harms for women.

When people talk about a false positive with respect to screening, it means that there’s something suspicious on the mammogram that later turns out to be nothing. It means you will to have an additional test – an ultrasound or an MRI, and only when that is still suspicious then ultimately a biopsy to diagnose breast cancer. If you are called back after a mammogram, there’s a high likelihood you do not have cancer. But getting that call increases a woman’s anxiety as she awaits the next steps. So, let’s call this “the anxiety of further testing”. If we could narrow the time between screening, follow-up, and the call that things are fine, this anxiety could be removed or drastically reduced. Again, not to simplify things too much, but on occasion, my smoke detectors go off in my home. For a few moments, I’m worried – is there smoke? Is there a fire? There’s none. This is also a false positive. But the length of time between the notification, the subsequent anxiety and the resolution is much faster. At Sunnybrook, we have the Rapid Diagnostic Unit that aims to get women with highly suspicious abnormalities to the follow-up testing and answers faster in order cut down that anxiety. Can we make this something that more women have access to at other health centres too?

As for overdiagnosis, a mammogram screening doesn’t diagnose cancer. A radiologist looks at the image and recommends further testing, and a person only gets diagnosed and treated for breast cancer if the biopsy confirms breast cancer. One thing the biopsy can’t yet do is determine who’s cancer will go on to cause great harm, and whose, if undetected, would have just been there for years without causing harm or death. So really, this is “overdetection” – spotting suspicious cancers via screening that would have gone on to do no harm. I would argue it’s still better to find those, and the breast cancer research community is making great strides in developing ways to determine which cancers will be most aggressive and should be treated aggressively.


Dr. Del Giudice

Dr. Lisa Del Giudice:

The Family Physician

“For most women aged 50-74, routine mammogram screening is worth it! It may save your life. And, know your breasts. If you notice a change to the size or shape or colour of your breast, see your healthcare provider.”

Read Dr. Del Giudice's full thoughts

The majority of average risk women aged 50-74 should participate in routine breast cancer screening with mammography. For most women in this age group, the benefits of screening will outweigh the risks. That benefit: a life saved.

The Canadian Task Force for Preventative Healthcare’s previous guidelines were a bit more rigid, and made it sound as though all average risk women aged 50-74 should participate in routine breast cancer screening and that all average risk women under the age 50 should not be screened. The previous recommendations did not allow for some women’s unique circumstances.

I think the confusion over the 2018 guidelines released last week stems from some of the language used. The new term “conditional recommendation” seems to be taking away from the main point here: that for most women age 50-74, mammograms are recommended. I think the point the task force is trying to make is that screening is always ultimately a personal choice, and that a woman’s own unique or extraordinary circumstances should factor in when she’s deciding whether or not to pursue mammogram screening.

There are benefits and risks – or limitations – to screening.

The main benefit of a mammogram in women aged 50-74: mammograms have been shown to save lives. By catching breast cancers early before they spread, they can be curable.

Some of the risks or limitations to consider would be false positive results, which is when something noted on the mammogram leads to more testing and sometimes a biopsy. Waiting for these tests/biopsies, as well as waiting for the results, can be anxiety-provoking, and for some it is an inconvenience to take time to attend these additional appointments. Sometimes biopsies can leave marks on the breast.

Overdiagnosis and overtreatment is also a potential harm. Some breast cancers, if left alone, may never cause problems such as spreading beyond the breast into the lungs, liver, bone or brain. The treatments used to prevent this from happening can sometimes leave women with long-term side effects. Unfortunately, we don’t yet have a reliable way to know which isolated breast cancer tumours will or will not spread – so when we find them, we are somewhat obligated to treat them.

I would encourage all women above age 40 to speak to their doctor about cancer screening and when to start, if it’s right for you. With your doctor, you can talk about your family history (for breast, other cancers and other illnesses), and you can talk more about the benefits and limitations of screening.

As family doctors, we know our patients very well and know our patient’s personal circumstances. When working with our patients, we consider their own values to help guide them in making healthcare decisions. For many of our patients, we also know about other personal, medical and psychosocial issues that could factor into their decision.

For example, let’s consider a woman under the age of 50 who is helping a friend who has breast cancer. While she may be at average risk for breast cancer, and the recommendations advise against screening in this age group, the anxiety about her own breast health may outweigh the anxiety of the mammogram and the anxiety of the aftermath of a false positive mammogram.

I haven’t turned 50 years old yet but when I do, I will certainly take part in mammography screening.


Belinda Curpen

Dr. Belinda Curpen:

The Radiologist

“I recommend all women get a mammogram each year. If it were up to me, this would begin at age 40. Currently, the Ontario Breast Screening Program advises women age 50-74 to get a mammogram every two years — so I appeal to women to consider taking part in that program at a minimum.”

Read Dr. Curpen's full thoughts

I’m a radiologist. I’m a woman. I’ve been having mammograms since I was 40. I’m now 54. I’ve had one excisional biopsy— that’s when the whole mass or lesion is removed by a surgeon in the operating room because there were abnormal cells in the needle biopsy. For me, it turned out to be nothing.

As a radiologist, I’m responsible for looking at screening mammograms for signs of cancer. Whether you are 40, 50, 60 or 70, the signs are the same. I’m looking for masses, calcifications and asymmetry. If a woman has yearly mammograms, the radiologists can compare and note any changes in the breast. There is less chance of a cancer appearing in the interval than if mammograms were done every two to three years.

Having the screening mammogram is the first step. It is not an exact science. We call back about 10 to 15 per cent of women after screening mammograms so that an area of concern can be studied more closely.

That might mean you come back for another mammogram or an ultrasound or MRI. About 20 per cent of those women will be called back again for a biopsy. If you need a biopsy, it doesn’t necessarily mean you have cancer. Most biopsy results are not cancer but this can be determined only after an analysis of the cells under a microscope.

I think it’s important that we educate people about these calls back — while I do understand it causes anxiety, please understand that it’s a necessary step in determining whether or not there is a cancer, just like if you were to be called back after a PAP test or a blood test. We are doing our due diligence to ensure that if there’s something amiss, we find it and treat it. What we need to remember is that most breast changes are not cancer.

But the statistics about breast cancer still astonish me. According to the National Cancer Institute, women in their 40s have a 1 in 217 chance of developing breast cancer. By age 45, that’s 1 in 93. By age 50, there’s a 1 in 50 risk of developing breast cancer. The risk continues to increase with age. Ultimately, we have a 1 in 8 chance of developing breast cancer in our lifetime if we lived up to 85 years old. Your individual risk may be higher or lower, depending on other factors, like family history and reproductive history. (More about risk factors here)

I don’t cite these numbers to cause you fear or panic. I want you to be aware of these numbers when you are weighing the benefits and limitations of taking part in mammogram screening.

If a cancer is caught early, there are treatment options available. This is particularly true for younger women, who tend to have more aggressive cancer.

If you are unsure or you want to discuss screening and your risk, talk to your family doctor. Tell them your family history of breast and other cancers. If you want to learn even more about your risk, ask for a referral to a genetic counsellor.

About the author

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Alexis Dobranowski

Alexis Dobranowski is a Communications Advisor at Sunnybrook.

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