Nav: Home

Cancer screening has never been shown to 'save lives,' argue experts

January 06, 2016

Cancer screening has never been shown to "save lives" as advocates claim, argue experts in The BMJ today.

This assertion rests on reductions in disease specific mortality rather than overall mortality, say Vinay Prasad, Assistant Professor at Oregon Health and Science University and colleagues.

They argue that overall mortality should be the benchmark against which screening is judged and call for higher standards of evidence for cancer screening.

There are two chief reasons why cancer screening might reduce disease specific mortality without significantly reducing overall mortality, write the authors.

Firstly, studies may be underpowered to detect a small overall mortality benefit. Secondly, disease specific mortality reductions may be offset by deaths due to the downstream effects of screening.

Such "off-target deaths" are particularly likely among screening tests associated with false positive results (abnormal results that turn out to be normal) and overdiagnosis of harmless cancers that may never have caused symptoms, they explain.

For example, prostate cancer testing yields numerous false positive results, which contribute to over one million prostate biopsies a year - which, in turn, are linked to serious harms, including admission to hospital and death.

Men diagnosed with prostate cancer are also more likely to have a heart attack or commit suicide in the year after diagnosis or to die of complications of treatment for harmless cancers.

Yet data has shown that the public has an inflated sense of the benefits and discounted sense of the harms of screening, they write.

For instance, in one study 68% of women thought that breast screening would lower their risk of getting breast cancer, 62% thought that screening at least halved the rate of breast cancer, and 75% thought that 10 years of screening would prevent 10 breast cancer deaths per 1000 women.

Yet they point out that the most recent Cochrane review of PSA screening trials "failed to show a reduction in disease specific death," while their mammography review "did not show reduced breast cancer deaths when adequately randomised trials were analysed."

Consideration of harms also becomes more important in the absence of clear overall mortality benefit, they add.

Advocates of screening have emphasised its benefits, sometimes verging on fear mongering, note the authors. Others, including us, think that shared decision making should be the focus.

"But as long as we are unsure of the mortality benefits of screening we cannot provide people with the information they need to make an informed choice. We must be honest about this uncertainty."

To find out whether screening saves lives, they say investing in large trials that can determine overall mortality is "worth the expense compared with the continued cost of supporting widespread screening campaigns without knowing whether they truly benefit society."

They acknowledge that political will, financial resources, and public perception "are common hurdles in building support for resource intensive scientific endeavours, and developing consensus on these matters will take time and effort."

And they call on healthcare providers "to be frank about the limitations of screening" and for higher standards of evidence "to enable rational, shared decision making between doctors and patients."

In an accompanying editorial, Gerd Gigerenzer argues that "rather than pouring resources into 'megatrials' with a small chance of detecting a minimal overall mortality reduction, at the additional cost of harming large numbers of patients, we should invest in transparent information in the first place."

He explains that even if the uncertainty of screening on overall mortality is not removed, we can provide people with useful tools to help with informed decision making, adding that "it is time to change communication about cancer screening from dodgy persuasion into something straightforward."

Useful tools such as fact boxes can illustrate harms associated with mammography screening, for example, by reporting all three measures of mortality (see article for an example). "The harms are specified numerically so that an informed decision about screening is possible. Every article and pamphlet should provide a fact box summary to facilitate informed decisions," he concludes.


Related Breast Cancer Articles:

Breast cancer: AI predicts which pre-malignant breast lesions will progress to advanced cancer
New research at Case Western Reserve University in Cleveland, Ohio, could help better determine which patients diagnosed with the pre-malignant breast cancer commonly as stage 0 are likely to progress to invasive breast cancer and therefore might benefit from additional therapy over and above surgery alone.
Partial breast irradiation effective treatment option for low-risk breast cancer
Partial breast irradiation produces similar long-term survival rates and risk for recurrence compared with whole breast irradiation for many women with low-risk, early stage breast cancer, according to new clinical data from a national clinical trial involving researchers from The Ohio State University Comprehensive Cancer Center - Arthur G.
Breast screening linked to 60 per cent lower risk of breast cancer death in first 10 years
Women who take part in breast screening have a significantly greater benefit from treatments than those who are not screened, according to a study of more than 50,000 women.
More clues revealed in link between normal breast changes and invasive breast cancer
A research team, led by investigators from Georgetown Lombardi Comprehensive Cancer Center, details how a natural and dramatic process -- changes in mammary glands to accommodate breastfeeding -- uses a molecular process believed to contribute to survival of pre-malignant breast cells.
Breast tissue tumor suppressor PTEN: A potential Achilles heel for breast cancer cells
A highly collaborative team of researchers at the Medical University of South Carolina and Ohio State University report in Nature Communications that they have identified a novel pathway for connective tissue PTEN in breast cancer cell response to radiotherapy.
Computers equal radiologists in assessing breast density and associated breast cancer risk
Automated breast-density evaluation was just as accurate in predicting women's risk of breast cancer, found and not found by mammography, as subjective evaluation done by radiologists, in a study led by researchers at UC San Francisco and Mayo Clinic.
Blood test can effectively rule out breast cancer, regardless of breast density
A new study published in PLOS ONE demonstrates that Videssa® Breast, a multi-protein biomarker blood test for breast cancer, is unaffected by breast density and can reliably rule out breast cancer in women with both dense and non-dense breast tissue.
Study shows influence of surgeons on likelihood of removal of healthy breast after breast cancer dia
Attending surgeons can have a strong influence on whether a patient undergoes contralateral prophylactic mastectomy after a diagnosis of breast cancer, according to a study published by JAMA Surgery.
Young breast cancer patients undergoing breast conserving surgery see improved prognosis
A new analysis indicates that breast cancer prognoses have improved over time in young women treated with breast conserving surgery.
Does MRI plus mammography improve detection of new breast cancer after breast conservation therapy?
A new article published by JAMA Oncology compares outcomes for combined mammography and MRI or ultrasonography screenings for new breast cancers in women who have previously undergone breast conservation surgery and radiotherapy for breast cancer initially diagnosed at 50 or younger.
More Breast Cancer News and Breast Cancer Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at