Mammography 'does not reduce breast cancer deaths'

After skin cancer, breast cancer is the most common cancer among American women. Around 231,840 women in the US will be diagnosed with breast cancer this year, and around 40,290 will die from the disease.

As with other cancers, early detection of breast cancer is key for successful treatment, and this can be achieved through breast cancer screening. The main tool used for breast cancer screening is mammography, which involves taking an X-ray of each breast, allowing clinicians to see any tissue abnormalities.

The US Preventive Services Task Force (USPSTF) recommend that women aged 50-74 have a mammogram every 2 years.

According to the American Cancer Society, death rates from breast cancer have been falling since around 1989, and this is partly attributed to earlier detection as a result of breast cancer screening.

However, study co-author Richard Wilson, of Harvard University in Cambridge, MA, and colleagues note that there is increasing concern that mammography may lead to overdiagnosis by "identifying small, indolent or regressive tumors that would not otherwise become clinically apparent," which means many women may receive treatment they do not necessarily need.

What is more, although clinical trials have shown mammography is effective for early breast cancer diagnosis, Wilson and colleagues note that most of these trials are decades old. "There are concerns that the benefits and harms may have changed as treatments improved and screening was applied in general practice," they add.

Breast cancer screening increased diagnosis by 16%, but did not reduce death rates

For their study, the team set out to assess the link between rates of mammography for breast cancer detection and breast cancer incidence, tumor size and death rates from the disease.

They analyzed data from the Surveillance, Epidemiology and End Results (SEER) cancer registries, involving more than 16 million women aged 40 and older from 547 counties in the US.

Breast cancer was diagnosed in 53,207 of these women during the 12-month period, and these women were followed-up over the next 10 years.

The rate of breast cancer screening was assessed in each county, as determined by the percentage of women who underwent a mammogram in the previous 2 years.

Overall breast cancer incidence in the year 2000 was calculated for each county, as was the rate of breast cancer deaths during the 10-year follow-up. The team age-adjusted this data and applied it to the US population.

The results of the analysis revealed a 10% rise in breast cancer screening. This was associated with a 16% increase in breast cancer diagnosis. However, no reduction was found in the rate of breast cancer deaths.

In addition, the 10% increase in breast cancer screening was linked to a 25% rise in incidence of small breast cancers - defined as the presence of tumors 2 cm or less. However, the increase in breast cancer screening was not associated with a reduction in incidence of larger breast cancers - it was linked to a 7% increase.

Commenting on their findings, Wilson and colleagues say:

"Across US counties, the data show that the extent of screening mammography is indeed associated with an increased incidence of small cancers but not with decreased incidence of larger cancers or significant differences in mortality.

What explains the observed data? The simplest explanation is widespread overdiagnosis, which increases the incidence of small cancers without changing mortality, and therefore matches every feature of the observed data."

Clinicians 'right to be wary' of breast cancer screening studies

The researchers add, however, that clinicians are right to have concerns about ecological studies regarding breast cancer screening because of "ecological fallacy." Dr. Joann G. Elmore, of the University of Washington, agrees with this statement in a linked editorial.

"It is well known, for example, that ecological studies provide no information as to whether the people who were actually exposed to the intervention were the same people who developed the disease, whether the exposure or the onset of disease came first, or whether there are other explanations for the observed association," she explains.

As such, she says better tools and communication are required to help women make informed decisions about breast cancer screening.

"Perhaps most important, we need to learn how to communicate with our patients about uncertainty and the limits of our scientific knowledge," she adds. "In the end, we all need to become comfortable with informing women that we do not know the actual magnitude of overdiagnosis with precision. Part of informed decision making is providing all the information, even our uncertainty."

In contrary to these latest findings, a study reported by Medical News Today last month claims mammography is the best screening method for reducing breast cancer mortality among women aged 50 and older.

[Original Article]

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Anesthesiology Lessons for Rwandan Residents: Troubleshooting Intraoperative Hypoxemia from the Lounge of a Luxury Hotel

How does a country with 13 anesthesiologistprovide anesthesia care for a population of 12 million? In Rwanda, since 1997, anesthesia technicians have provided anesthesia in the operating theater after undergoing a 3-year training program, which they could enter from high school. Prior to the initiation of the first anesthesia residency class in Rwanda in 2006, the country had only 3 physician anesthesiologists who were trained in France and Belgium. The lack of any educational infrastructure prior to independence from Belgium in 1962, and the long-standing ethnic conflicts between the Tutsi�s and Hutu�s have hampered the development of medical care and education system. However, though in its ninth year of operation, the anesthesia residency program currently has only 9 out of its 24 positions filled. In sharp contrast to the rising popularity of anesthesiology as a career choice in the U.S. and Canada, few medical graduates in Rwanda choose anesthesiology due to a combination of high-stress, disproportionate patient morbidity and mortality, low salary and long hours, and excessive clinical and administrative burden.

With this dire shortage of physician anesthesiologists, the clinical role that these residents are expected to fill is utterly different from the role that I, as an anesthesiology resident in the U.S., am trained to fill. Rather than directly providing the anesthesia care, the Rwandan anesthesiologists will be mostly acting as consultants to the anesthesia techs. Currently, the techs could discuss complicated cases with the anesthesiologist on call, and can phone them when problems arise. Consequently, the residents infrequently take responsibility for a case from beginning to end. As well, with the responsibility to take overnight ICU calls, the residents are in the operating theater only about 2-3 days a week. This severely limits their intraoperative training and exposure to the infrequent but high acuity events that require rapid troubleshooting, diagnosis, and decision-making.

A key aspect to highlight is that with the shortage of physician anesthesiologists, in the absence of foreign anesthesiologists, the anesthesia residents would be learning anesthesia mainly from books and the anesthesia techs. This is an educational gap that the U.S. physicians working in Rwanda through the Human Resources of Health (HRH) collaborative have filled. The anesthesia techs perform a very admirable job of placing thousands of patients under general anesthesia and bringing them safely through surgery, especially for patients with advanced stages of disease and uncontrolled comorbidities that anesthesiologists in the developed world are mostly shielded from. However, without having been through college or medical school, they lack the fundamental understanding of physiology and disease processes that would alert physicians to perform more thoughtful preoperative investigation and optimization, and to manage the intraoperative and postoperative course. This became evident when I went with a U.S. attending anesthesiologist and the local resident he is paired with to the wards to evaluate patients with inexplicably high blood pressures, possible untreated heart failure, or pulmonary problems. Although the anesthesia techs had already performed a preoperatively evaluation of each patient the evening before, we felt strongly that further optimization and discussion with the primary team was necessary and postponed the cases. Thus, a critical aspect of the U.S. physicians� interactions with the anesthesia residents is encouraging them to apply their medical education and years of practice as a general practitioner to think and act as a physician.

Under these circumstances, simulation is a critical component to the residents� didactics to create opportunities for making managing complicated or emergency scenarios. However, the simulation center was recently shut down due to lack of funding for a managerial administrator. Also, as commonly happens to expensive equipment sent to developing countries lacking the technical support for maintenance, the SimMan requires repair and can function now only as a low-fidelity mannequin. Thus, instead of designing a classical intraoperative scenario, I designed cases where the residents were called on the phone to help an anesthesia tech manage an intraoperative event. Considering the role of anesthesiologists as consultants, not using the SimMan actually better approximates their future responsibility.

Another unanticipated challenge of simulating the case was relocating our class at a moment�s notice to the lounge of a hotel. We learned just when class was about to begin that no room was available at the college due to exams. This experience in teaching anesthesia in a low-resource country has challenged me to identify educational and knowledge gaps through careful observation, to tailor lessons to local practices, and to be flexible in adjusting to surprise circumstances. Thankfully, the two first-year residents I worked with were very obliging, and engaged fully in the scenario. Meanwhile, we were able to enjoy the perks of having class at a 5-star hotel � high-speed wifi, plush couches, and fine Rwandan coffee.

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Editor's Note #23: Tweepidemiology#2..

Thought it was time to update the "Tweepidemiology" graph I first posted back in September of 2014.

The Ebola virus disease epidemic of 2014 certainly drive the biggest of my Tweepidemics.

Followers of my @MackayIM Twitter account (and this blog which gets
promoted through it) since I started tweeting.
This shows the cumulative rise, and pause, of followers and the relationship between the rate of that rise and some active periods of infectious disease outbreaks..
Click on the graph to enlarge

This will be something I check back in on from time to time. Interesting stuff. 

As above but zoomed in to show the dip in followers of the @MackayIM Twitter account.
Click on the graph to enlarge.

Something else this little analysis showed me was still interesting, but very disappointing. That thing was one of the biggest losses of followers and slowest periods of follower gains that my Twitter account has had in its 2 years. 

This dip happened immediately after I changed the background on my avatar to reflect my support for the US Supreme Court's legalisation of same sex marriage. I kept that background for a week. I haven't been able to find anything else to attribute to the dip - I haven't been any more annoying or rude than I usually am! I don't blog to gain followers per se but followers are very helpful because they help spread sometimes useful information further than it might otherwise reach. Also, because you're mostly a likable bunch of course! In the scheme of things it was a blip - and there is always a turnover of newcomers and "newleavers" and the latter generally increases in proportion to a decrease in my level of engagement. It just strikes me as sad that people feel so much dislike or annoyance that they need to respond by leaving the table in disgust or annoyance like a child who doesn't get what they want.

Data. So many things to learn from them.

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