One of our target lines for research is based on assessment of benefits and harms of population-based breast cancer screening. We have been developing this research line for nearly 20 years. One of the key questions when we try to assess breast cancer screening is if it is efficient. By this we mean that actually, at least in Europe, all women aged 50-69 are offered a screening mammogram every two years just for early detection of breast cancer. The question is if offering a mammography every two years to every woman, that means a one size fits all strategy, if that is sufficient or maybe if we should go a little bit deeper and try to personalise the breast cancer screening strategies. When we talk about this, one of the key questions is the risk factors for breast cancer which is the information that we need to use if we want to personalise breast cancer screening strategies.
So, one of those key risk factors is benign breast lesions. When we talk about benign breast lesions or benign breast disease it’s the effect that it has on the risk factor and how long it lasts. That’s one of what we wanted to see in this study is how the effect of benign breast lesions, how long it lasts over time. We found that it lasts for 20 years and that the risk kept steady stable for 20 years and that’s the key finding.
To do this we used a retrospective cohort of screened women in different areas of Spain. We have a screening cohort which goes from the mid ’90s to the actual time so that means more than 20 years of follow-up of women who have been screened bi-annually since the mid ‘90s.
What were your findings?
The key finding is that we know that previously that benign breast lesions are a risk factor for breast cancer because we have published that previously and there are many other studies that contribute to that information. But what we wanted to demonstrate, and that’s what is new, is for how long this increasing risk lasted. To do that we need long cohorts and that’s what we have in our programme and in our research, like this follow-up for 20 years.
We did a specific analysis where we wanted to check the effect of time over the risk. What we found is that independently of how long the benign breast lesion when it was diagnosed, the risk kept increased for 20 years with around a 1.8 relative risk.
How can these results impact the future screening and treatment of breast cancer?
We have two perspectives. One is more for individual women and when we talk about that we need to encourage women with risk factors, not only with benign breast disease but maybe with a family history of breast cancer, that they should go to organised breast cancer screening programmes. They should keep going to their screening programmes because they may benefit more from breast cancer screening than women with a low risk profile. So they should go to breast cancer screening.
In addition, if we want to talk about making breast cancer screening more efficient, instead of the one size fits all strategy that we are running right now, going into more detail and personalised follow-up, then this information is really important. Because we can make risk groups of women, to define women who are at a higher risk who might be women with benign breast lesions but also who may have a family history of breast cancer or a dense breast. If we have this information and we put it together we can calculate the risk for each woman and say, ‘This woman is a high risk woman, is an average risk woman, is a low risk woman.’ So with this information we can propose closer follow-up for women at high risk: maybe instead of a screening mammogram every two years maybe we should do it every year or even more. If they have a dense breast instead of mammography we can use an ultrasound or maybe an MRI. So that goes in that way.
But also for women who are at a low risk, that means that they don’t have a family history of breast cancer, no previous benign lesions, fatty breast, maybe we can offer them a four year screening interval. That means instead of coming every two years they will be screened every two years because we know they are at a lower risk of developing breast cancer. So it all goes in line with personalising strategies for breast cancer screening.
Do you think the age limit should be reduced for women that have a higher risk of getting breast cancer?
It makes sense. What you just said is a key question in the actual debate – if women at high risk should start screening earlier. It really makes sense that, at least in Europe, the screening age range goes from 50 to 69 but maybe we should start thinking on doing a first assessment of risk for women who become 40, probably. Around 40 years of age we can check these risk factors like family history, do a baseline mammogram, mammography, to see if they have any kind of breast lesion, also to check the breast density. With that information for those who are high risk it may make sense to start screening earlier. For those who are at a lower risk maybe we should wait until 50 because also the evidence from experts and from the evidence from the research says that the most efficient age-range is from 50 to 69. So there is no conclusive evidence that screening 40-50 might be efficient but at least for women who are at a higher risk it might be a legitimate question to start screening earlier.
Is there anything else you’d like to add?
I would like to highlight that we should not take the findings in this study as an alarm. Okay, women with benign breast disease have a higher risk, of course they have, but that does not mean that they are going to develop the disease. It means that they are at a higher risk but keep in mind that the detection rate in breast cancer screening programmes is around 5 breast cancers for every 1,000 screening mammograms. If they are at a double risk of breast cancer, that means that 10 out of 1,000 screening mammograms may be detected with breast cancer for women with a previous benign breast disease. So that means they are at a higher risk, they should go to breast cancer screening programmes, but we should not start an alarm saying, ‘Oh, they are at a higher risk,’ because probably most of them will not develop the disease anyway. So just to try to send a calm message to them.