Screening: put to new use

Mammograms have recently been discovered as a way to check for cardiovascular health in women, and this could soon be one of their primary functions as fewer healthcare boards are recommending them for their more tradition purpose: to check for the earliest stages of breast cancer.

This is not because there’s anything wrong with the mammograms – they are still a perfectly sound medical process – but, rather, the problem lies with the fact that they highlight tumours and lesions that are so small they often don’t ever develop into cancers that need treatment, but overcautious doctors have still been sending these women in or treatment.

It’s believed by many that mammograms are the best way for detecting cancers, even at the earliest stage, since they provide very high-quality images. In fact, they may have been too good. Many in the healthcare sector now believe that breast-cancer screening programmes are overdiagnosing cancers, which may or may not be life-threatening, and that this could be having a detrimental effect on the patient’s quality of life and that breast-cancer screening should be withheld until the patient exhibits a more pronounced possible illness.

A recent study led by Dr Karsten Jørgensen from the Nordic Cochrane Centre in Copenhagen, a centre that is part of the Cochrane Collaboration, has shown that this controversial hypothesis may be true. (While the Nordic Centre primarily carried out the epidemiological study produced, it was not under the Cochrane Centre organisation’s name, and the centre does not claim the results as its own.)

The goal was to prove the effectiveness of breast-cancer screening and whether or not it should be used to detect early-stage cancer and prevent advanced disease.

“We’re an independent research collaboration,” Jørgensen says from their offices in Copenhagen’s most prestigious hospital, the Rigshospitalet. “Our research institute is funded by the Danish Government, and we try to remain as independent as we can.”

Jørgensen has been conducting research at the centre for the past 14 years, and even did his thesis on breast screening three years ago, for a doctorate of medical science. “We’ve been writing about this for a while; it started off with our director, Professor Peter Gøtzsche, who did a systematic review on breast-cancer screening as an assignment from the Danish Government. He was the first to show that incidence was higher among women who were offered breast screenings than in women who were not offered a screening, and he attributed this to overdiagnosis,” Jørgensen says.

“That was a controversial finding at the time; it was on the front page of The New York Times, and he wasn’t allowed to publish this; he had to go to the Lancet  as there was so much opposition.”

Controversial opinion

Jørgensen and the team, which included doctors and other medical professionals from the University of Oslo and Norwegian Institute of Public Health, set an objective for a new study: to assess the association between screening and the size of detected tumours, and to estimate overdiagnosis (detection of tumours that would not become clinically relevant).

The study was conducted with results from a period of 1980 to 2010 and included women from early middle age to 85 years old. Denmark has differing levels of breast screening; the country is split into five regions, all of which have autonomy of their healthcare funding and requirements. In some of the regions, it was compulsory to offer breast screening, and, in some others, screening was not offered at all.

“We’ve tried to take advantage of a unique situation here in Denmark,” Jørgensen explains further. “Two of these administrative regions decided to introduce breast-cancer screening in the early ’90s, but it was only 17 years later that the remaining regions introduced screening, at the requirement of our government – which wouldn’t accept differential access to that level of care.

“But prior to that, the majority of regions had assessed that breast-cancer screening was not a good way to spend resources, and they didn’t offer it. That gave us a natural experiment; women living in these two regions that offered breast-cancer screening for 17 years and then compare what happened with those to women living in areas not being screened,” he adds. “Because that’s been a criticism of previous studies, where people had tried to estimate the amount of overdiagnosis; if you introduce breast-cancer screening at the national level, you have to guess what would happen if you hadn’t introduced it, and estimate expected incidence rates in the absence of screening.

“That gives you estimates that are less certain than if you don’t have to make such a guess. You can just observe what’s actually happening. Our study is closer to a randomised trial in that we have this control group of unscreened women.”

The results showed that screening was not associated with lower incidence of advanced tumours. The first of these found that 271 invasive breast-cancer tumours and another 179 ductal carcinoma in-situ lesions (DCIS) were overdiagnosed in 2010. DCIS is the most common type of non-invasive breast cancer among women, where the cancer starts inside the milk ducts.

According to the research findings, this meant an overdiagnosis rate of 24.4% (including the DCIS, or 14.7% when excluding DCIS). The report states that the second approach, which accounted for regional differences in women younger than the screening age, found that 711 invasive tumours and 180 cases of DCIS were overdiagnosed in 2010. This included an overdiagnosis rate of 48.3% including DCIS and 38.6% excluding DCIS.

The team concluded their study with the simple statement: “Breast cancer screening was not associated with a reduction in the incidence of advanced cancer.” Their conclusion continued with the takeaway that “it is likely that one in every three invasive tumours and cases of DCIS diagnosed in women offered screening represents overdiagnosis”.

Another perspective

This is not the only study that has come up with these factors either. Some researchers have gone so far as titling their investigations ‘Why getting a mammogram may cause more trouble than it’s worth’.

The American Cancer Society first started recommending mammograms to women in 1976, and screening reached its peak in 2000, when a whopping 70.4% of women 40 years old and older had mammogram at least ‘semi-regularly’ (every two years).

As screenings increased, so too did breast-cancer diagnoses, which was exactly the idea. The new-found care and consideration on the topic spread; mothers and daughters, no matter what age, were supposedly to take notice. Mammograms became a regular chore to be done for most – unpleasant but necessary – and firmly rooted in the idea of self-care.

However, one thing wasn’t changing that much, even with the uptake in this process, and the fact that millions were spent on advertising and educating women on early interventions: the number of diagnoses of late-stage breast cancer.

It is true that breast-cancer screening were catching a greater number of tumours in the early stages, but by and large these were the slow-moving types.

“Overdiagnosis is basically giving the individuals a cancer diagnosis that they never would have otherwise had, and that would never have affected their health,” says Jørgensen of this result. “And getting that cancer diagnosis is a life-changing event for most; it has huge implications for their quality of life and the quality of life for their family.

“Then there are the physical consequences, because you don’t know who will suffer from the overdiagnosis, so everyone needs to have the treatment. And, of course, you don’t engage in cancer treatment for fun. And if you end up getting chemotherapy, it’s something that can increase your chance of other diseases,” Jørgensen adds.

“So, it’s something that has implications for many people and that’s the reason that we’re concerned. That’s the reason overdiagnosis has become regarded as the most important harm, and harm that can actually challenge the justification of this particular type of cancer screening.”

Thinking again and ahead

If cancer screenings had been finding more dangerous cancers early, there would have been fewer cancers to catch at later stages, but that has not happened in 40 years. The annual number of deaths from breast cancer has dropped, but experts say that’s largely because of improvements in treatment, not early detection. And what’s more, it is the breast-cancer deaths among women younger than 50 that are decreasing the fastest, a group who get fewer routine mammograms.

There has been a subset of medical professionals saying that breast-cancer screenings aren’t worth the fuss for several years. In 2013, a Swiss panel of experts released a paper saying that screenings weren’t helping, weren’t catching cancers that killed and left disfigurement or required heavy treatment.

The Swiss results weren’t the first either: the US Preventive Services Task Force in 2009 recommended against universal breast cancer screening with mammography in women aged 40 to 49 years old. But the Swiss went further and took their case to the national board. According to Dr Arnaud Chiolero, from the Institute of Social and Preventive Medicine at Lausanne University Hospital in Switzerland, who studied the report and the effects of it on the Swiss medical community, its recommendations were rigorous: “The Swiss Medical Board stated that new systematic mammography screening programmes should not be introduced, irrespective of the age of the women, and that existing programmes should be discontinued.”

Jørgensen thinks it unlikely that a major change would just appear in one country, though, despite these opinions.

“I think changes would probably come to international guidelines. In Switzerland, they recommended that they shouldn’t introduce national breast-cancer screening, and in the cantons where they had a breast-cancer screening programme, [it] should have a timeline to disengage,” he says.

In November 2016, an independent group in France made the recommendations to their government that French breast-cancer screening should either be stopped or thoroughly reworked.

So the change is coming; the study in Denmark provides near-perfect results to show that overdiagnoses are leading to a serious problem and debates must be had.

“There is an inclination for people to want to do good, so people who have been working with breast-cancer screening do this out of a genuine wish to help people and seek that area because they think that breast screening can accomplish that,” Jorgensen concludes. “If you have that connection, and you’ve been working with breast screening for many years, it’s difficult to take a step back and look at the programme in an unbiased way, and it’s particularly difficult, perhaps, to recognise that the programme you’ve been working with for many years have actually led to important harms for quite a lot of women.”

It turns out we’ve been using mammograms’ extreme usefulness to create a potential form of mass hysteria. There’s no doubt they provide a great service and do exactly what we need them for, but the campaigns around them have been too focused on catching even the tiniest blemish and treating it.

What these studies prove, is that what we should use mammograms for is monitoring. But for now, their place is safe – and, as mentioned earlier, recent studies have shown they are a great way of identifying early onset heart diseases, without requiring surgery or medication, and provide a valuable resource to women. Screenings for younger, less-at-risk women, may eventually be cut, but it may be for the best.