ARRS: Patients overestimate mammography radiation danger
May 5, 2014 — Women overestimate the amount of radiation they receive from mammography exams, which could lead them to avoid screening, according to data presented at the American Roentgen Ray Society (ARRS) annual meeting in San Diego.
Radiation dose is a hot topic, and patients have a lot of questions about how much radiation they receive during a procedure and the possible effects of exposure, said lead researcher Jacqueline Hollada from the University of California, Los Angeles (UCLA) Iris Cantor Center for Breast Imaging.
“Understanding patients’ perspectives regarding ionizing radiation can help imaging staff address common misunderstandings,” she said.
Hollada and colleagues surveyed patients’ knowledge of radiation dose associated with mammography, including 1,350 women between the ages of 19 and 89 presenting for annual mammography over a nine-month period.
Jacqueline Hollada from UCLA’s Iris Cantor Center for Breast Imaging.
“Our main goal was to gauge patients’ perceptions of how much radiation they receive from mammography, compared to five benchmarks,” Hollada told AuntMinnie.com. “Telling a woman how many millisieverts an exam gives isn’t as useful.”
Hollada’s group asked survey participants to rate the amount of radiation in a single mammogram (0.4 mSv) as being significantly less, slightly less, about the same, slightly more, or significantly more than five radiation benchmarks arranged on a logarithmic scale, with 1 being the highest dose and 5 being the lowest dose:
- The limit for a radiation worker per year (50 mSv)
- The average yearly background dose (3.1 mSv)
- The average annual dose from food (0.3 mSv)
- The dose received from an airplane flight from Los Angeles to New York City (0.04 mSv)
- The extra dose received from spending two days in Colorado (0.006 mSv)
The researchers then determined how each participant ranked a mammogram among the radiation sources.
The average rank given for mammography was 2.95, which differed significantly from the correct rank of 3.5, Hollada said.
“The radiation dose for a mammogram falls between the annual dose from food and the average yearly background dose,” she told AuntMinnie.com. “On a logarithmic scale, a difference of 1 is multiplied by 10, so the difference between 2.95 and 3.5 is dramatic.”
Although the survey participants on average overestimated the radiation exposure of a mammogram, the majority (72%) said they believe the benefits of the exam outweigh the risks, said Hollada, who plans to continue the research.
“Going forward, we plan to investigate the benefits of including radiation benchmarks in educational materials, so that patients have a better perspective,” she concluded.
Copyright © 2014 AuntMinnie.com
AJR: Skipped breast screenings increase cancer risk
October 29, 2013 — When women skip a mammography screening exam — even for just one year — their risk of late-stage cancer increases, according to a new study published in the November issue of the American Journal of Roentgenology.
These findings conflict with the revised 2009 mammography screening guidelines from the U.S. Preventive Services Task Force (USPSTF), which state that women should start screening mammography at age 50, rather than 40, and continue thereafter biennially through age 74, the authors wrote.
Missed mammograms represent missed opportunities for earlier breast cancer diagnosis, according to lead author Dr. Adedayo Onitilo, from Marshfield Clinic Weston Center in Weston, WI, and colleagues.
“As a practicing oncologist, I see a lot of women who have never had mammography, and up to about 20% of them are younger than 45,” Onitilo told AuntMinnie.com. “When they finally present for their first mammogram, they often have more-advanced disease.”
For the study, Onitilo and colleagues parsed patient characteristics associated with missed mammograms and examined the association between the missed tests and breast cancer stage at diagnosis. They identified 1,428 women with breast cancer diagnosed between January 2002 and December 2008 (53 were eventually excluded, leaving 1,368 for analysis).
The researchers collected demographic and other information including the following:
- Number of medical encounters during the study period
- Insurance status
- Medical and family history
- Any mammograms within five years of breast cancer diagnosis
- Other cancer diagnoses
- Residence location
- Reasons for not undergoing mammography
Using mapping software, the team also estimated patients’ travel time from their residence to the nearest mammography screening clinic (AJR, November 2013, Vol. 201:5, pp. 1057-1063).
Regardless of age, the women in the study cohort who had regular mammograms were more likely to have early-stage breast cancer at diagnosis, compared with those who did not undergo mammography, Onitilo’s group found.
The difference between women who had undergone mammography screening and those who had not increased incrementally with each additional year: Those with no mammograms in the five years before breast cancer diagnosis had an 18% increase in late-stage disease at diagnosis. Put another way, more than 50% of the women included in the study with late-stage breast cancer missed five out of five annual mammograms before their disease was found.
Even one skipped year makes a difference, according to Onitilo and colleagues.
“Our results are in direct contradiction to the USPSTF guidelines,” they wrote. “We found that even one year makes a significant difference in diagnosis of early- versus late-stage breast cancer. Women without a mammogram in the one year before a breast cancer diagnosis had a 12% increase in the risk of diagnosis of late-stage breast cancer compared with those who underwent annual mammography. This percentage difference was consistent in women older and younger than 50 years.”
Why did women skip mammograms? The most common factors included not having a family history of breast cancer, fewer medical encounters of any kind, and increased travel time from home to the mammography center. (In fact, they found that each additional minute of travel time decreased the odds of a woman undergoing at least one mammographic examination in the five years before her cancer diagnosis.)
Primary care physicians can play a crucial role in encouraging women to get regular breast cancer screening — and creative scheduling can help, too, the authors noted.
“[Patients] who must travel a greater distance for healthcare services, including mammography, may benefit from additional counseling or the opportunity to schedule screening mammography for the same day as an annual physical examination to avoid making multiple trips to the clinic,” they wrote. “In addition, the annual physical should be used to emphasize the importance of annual mammography to women with no comorbid conditions, because this may be their only contact with the healthcare system throughout the year.”
The complexity of factors that contribute to a woman skipping regular breast cancer screening exams suggests that guidelines such as the USPSTF’s are not nuanced enough, according to Onitilo.
“When you’re talking about individual patients, one size does not fit all,” he told AuntMinnie.com. “Individual risk needs to be assessed, and screening protocols personalized.”
Copyright © 2013 AuntMinnie.com
Study: Lack of breast screening leads to more cancer deaths
September 9, 2013 — A new study published online September 9 in the journal Cancer has found that more than 70% of deaths from breast cancer in a group of more than 7,000 women occurred in individuals who did not receive regular screening mammograms. The findings indicate that breast screening saves lives — particularly for women in their 40s, the researchers believe.
The use of mammography for breast cancer screening in women between the ages of 40 and 49 has been controversial, especially since the U.S. Preventive Services Task Force (USPSTF) proposed in 2009 to limit screening to women ages 50 to 74 years — and then biennially rather than annually.
Since the USPSTF announcement, the field of women’s health has been roiled by dueling clinical studies coming down for and against breast cancer screening. Some skeptics have advocated that screening be limited to older women per the USPSTF guidance, while others have gone further, casting doubt on the efficacy of breast screening for women in any age group. Mammography advocates have fired back with studies of their own backing breast cancer screening.
To address the controversy, researchers from Massachusetts General Hospital, Harvard Medical School, and other Boston institutions examined the value of mammography screening using an analytical technique called failure analysis, which involves analyzing a “failure” — in this case, the death from breast cancer — and why it occurred. The researchers used the technique to look backward from death to uncover correlations between the patients who died and whether they received breast screening (Cancer, September 9, 2013).
“In the presence of conflicting evidence, national recommendations for screening mammography have become a point of contention,” wrote corresponding author and surgical oncologist Dr. Blake Cady and colleagues. “Surgical procedures, systemic adjuvant therapies, and radiation treatments for breast cancer have changed over recent decades, and as breast cancer mortality continues to decline, it is important to determine the proportional decrease in mortality, if any, that is due to modern mammography.”
Cady and colleagues used data from two hospitals, Massachusetts General Hospital and Brigham and Women’s Hospital, both part of the Partners HealthCare system. The team tracked invasive breast cancers diagnosed between 1990 and 1999 and followed through 2007.
The dataset included information on demographics, mammography use, surgical and pathology reports, and recurrence and death dates. To verify that a patient had died of breast cancer, the researchers used proof of distant metastatic disease by biopsy, other operation, radiological pattern, or laboratory or clinical reports. They also used clinical and progress notes, death certificates, hospital discharge summaries, and autopsies.
Among 609 confirmed breast cancer deaths, 29% were among women who had been screened with mammography, while 71% were among women who were not screened regularly. Also, the women who died of breast cancer were younger: Of all breast cancer deaths, only 13% occurred in women age 70 or older, but 50% occurred in women younger than 50.
“If half the deaths of women who develop breast cancer and die occur in women under the age of 50, that implies we could probably prevent many of those deaths by screening women in their 40s,” Cady told AuntMinnie.com.
Breast cancer mortality in the 7,301 women with invasive breast cancer diagnosed between 1990 and 1999 was only 9.3% at a median of 12.5 years, compared with 50% mortality before 1969, according to the authors. And with more prevalent regular screening, particularly in younger women, breast cancer mortality could decrease to much less than 10% overall in the coming decade — perhaps becoming as low as 5% overall by 2030.
“I did my medical training in the ’60s, and I have seen with my own eyes the dramatic difference in mortality rates since breast cancer screening was introduced,” Cady said.
Why failure analysis?
Why did the researchers choose the failure analysis technique? Because randomized, controlled trial data — and meta-analyses of these data — can misjudge the effectiveness of screening mammography, according to Cady and colleagues.
“Meta-analysis of trials underestimate true effectiveness of mammography due to compliance and contamination biases in experimental and control groups, respectively,” they wrote. “Population-based evaluations of women actually screened usually show reductions in mortality much greater than those found by randomized, controlled trials.”
Critics may say that failure analysis is not appropriate for evaluating screening mammography because it’s not a randomized trial. But the process is an important discipline, according to Cady.
“Failure analysis is a standard part of not only academic medicine, but also many other fields,” Cady told AuntMinnie.com. “Think of those black boxes in airplanes — that’s failure analysis. Every week in surgical service, we have a morbidity and mortality conference, reviewing the cases of patients who died to determine what happened. That’s a failure analysis, too. It’s a different way of looking at things.”
The data used by USPSTF actually demonstrated that annual screening improved outcomes, he said.
“The USPSTF performed a meta-analysis of randomized, controlled trial data, and then made models based on that, from which they drew their conclusions,” he said. “And their models showed that annual screening improved outcomes by 70%. But their paper did not discuss that. They were concerned with how resources would be allocated, and emphasized the ‘harms’ of screening mammography rather than the benefits.”
Cady’s team hopes that the study will spark further investigation.
“In the debate over screening mammography, the believers believe and the disbelievers don’t,” Cady told AuntMinnie.com. “A single study won’t change their minds. But we hope our findings will stimulate others to conduct further research and to look more critically at the current recommendations.”
Copyright © 2013 AuntMinnie.com
May 14, 2013
Today, Deb Matthews, Minister of Health and Long-Term Care, made the following statement regarding the release of a new study on mammography screening technology: A new peer-reviewed study by Cancer Care Ontario senior scientist Dr. Anna Chiarelli, published today in the journal Radiology, shows that direct radiography (DR) mammograms and screen-film mammograms are better at detecting breast cancer than computed radiography (CR) mammograms. CR mammography is used for approximately 20 per cent of mammograms in Ontario.
Ontario is committed to being a world leader in cancer care, which is why our government is making changes based on this new information and the advice of our experts. With the support of health care providers, Ontario will phase out CR devices across Ontario over the coming months.
To support this transition, our government is making a $25 million investment to replace all CR devices with new DR devices to ensure women continue to get the most effective screening for breast cancer using the best technology available. Cancer Care Ontario has issued a request for proposals to procure new DR devices and clinics will also be able to choose to purchase replacements on their own. We will work with health care providers to ensure the best possible care for women over the transition period, and co-ordinate the replacement of CR devices to ensure that care needs are met.
I want women to know that regular mammograms remain the best way to detect breast cancer, and that the chance of having an undiagnosed cancer using CR technology is extremely low. Women with questions about how the changes affect them are encouraged to contact the site where they were last screened, their primary health care provider, or Cancer Care Ontario.”