New study out of Norway: calling mammograms into question

A new study came out of Norway and appeared in the New England Journal of Medicine recently, casting doubt on the benefit of mammograms.  It analyzed data on over 40,000 women, aged 50-69yrs, over a nine year period, and found that mammographic screening alone accounts for a modest 10% decrease in breast cancer death.

Based on these results, some naysayers may want to denounce the use of regular mammograms to help the battle against breast cancer.  But I would disagree.  As with any study, we need to consider the possibilities.

Partial list of risk factors for breast cancer

• Genetics: BRCA-1 and BRCA-2
• Family history
• Age: increased risk with age
• Obesity
• Excessive alcohol use
• Lack of physical exercise

This list is hardly complete, but I want to stress a point: looking at one group of women leaves open many possibilities.  

• Do the BRCA gene mutations run in the Norwegian population?  Since it does have a prevalence in the American population, this is an important question.
• Obesity: a very clear risk factor; America has a definite problem with obesity, does Norway?
• Excessive alcohol use: is this prevalent in Norway?
• Lack of physical exercise: America is not known as a very active nation, how does Norway compare?

Those four questions alone could drastically change the outcome of the study.  If the population is less likely to develop breast cancer in general, then mammograms will diagnose breast cancer less frequently.  We also have to consider the presentation of breast cancer: how do lifestyle and genetics affect the radiographic presentation of breast cancer?  This too could affect the outcome of the study.

Other studies contradict the Norwegian study, and I have to agree with the contradictions, although on different grounds.  Mammography does not expose a woman to significant levels of radiation.  What significant disadvantages exist?  

Even going by this Norwegian study: 10% more lives saved is 10% more than zero.

For the record: One study is hardly enough to change a well practiced medical routine.

Mette Kalager, M.D., Marvin Zelen, Ph.D., Frøydis Langmark, M.D., & Hans-Olov Adami, M.D., Ph.D. (2010). Effect of Screening Mammography on Breast-Cancer Mortality in Norway NEJM, 1203-1210

http://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-risk-factors

Where to begin?

I began this blog as a means of discussing science, both old and accepted as well as new and open for question. In reality all science can be viewed as open for question.  Without questioning things rarely change, because they have no reason to.  When we accept something as fact and without question, we essentially end any discussion of an alternative.  Just as in the past, today is no exception in that we have people against this idea of questioning.  Take for instance evolution, one unnecessarily hot topic.

Evolution began as an idea originally postulated by two men: Charles Darwin and Alfred Russel Wallace.  Previously the work of a Catholic monk, Mendel, had suggested the basic mechanism of evolution.  These former two men suggested that nature selects who moves on to pass on their genes, and who does not and thus disappears.  This simplistic explanation belies the true science behind evolution, but let me try to explain it:

An offspring is born with various mutations, most of which go unnoticed throughout his lifetime.  However, sometimes the environment of that offspring changes, thus making the mutation useful.  In this instance he thus has an advantage over those around him, and therefore has a greater likelihood of passing on his genes.  Each of his offspring inherits the advantageous gene, and so on.  Overtime a population develops to survive their environment, and adapts through this genetic process to survive changes in the future.

To put an example to it: an individual is born with a mutation that affects his immune system, making it lack a certain biochemical marker.  Because the immune system has numerous pathways this individual notices no difference in health compared to others around him.  However, a new and unknown virus breaks out in the population, which requires that specific biochemical marker in which to enter cells.  Some survive by chance, but most perish.  Meanwhile this individual survives not by chance but by merit of this mutation.  He then mates and passes on this gene.  In the future when the virus reappears in the population his children will have an advantage over those without this trait, and over time their genes will come to dominate the gene pool.  Similarly other mutations will be selected for as the environment changes.  Some will select for physical characteristics, others for biochemical, and so on; surviving disease, getting food, attracting mates---these characteristics serve a purpose to increase the likelihood of survivability.  Thus with time the population evolves, adapting to its environment through changes to its gene pool.  For some species this can take as little as days, where as for others it can take hundreds of thousands of years.  Nonetheless enough research has backed this science that it has reached the level of theory, something not easily attained in the world of science.

This theory, however, has come under attack from those who wish to adhere to the Biblical story of creation. The stories of Adam & Eve romanticize the origin of humanity, promoting the belief that a deity created humans.  This group of people uses the term theory loosely, referring to their story of creation as a theory in its own right.  While it lacks the protocols requisite of a scientific theory, they insist it has as much merit as evolution.  But why?  Why does the idea of evolution create so much fear and hostility with this group?  I do not know, but to drop evolutionary science would set science back.  In fact, to disregard it outright would essentially deny any importance to genetics.

I do not wish to come off as anti-Bible.  In fact, I hold a strong belief in God.  But to understand science and to watch it grow, we need to put aside our firmly held beliefs in order to question.  This all brings me back to my original question: where to begin?  Let's begin with approaching science with a clean slate, and later justifying any realities discovered along the way.

Internal Medicine

Part 1: Patient Encounter- note writing and presentation

Cardiology

Part 1: Physical Exam

Part 2: Murmurs

Part 3: Jugular Venous Pressure

Hematology / Oncology

Part 1: Anemia

Part 2: Sugar-Baker Procedure

Part 3: Norwegian study on mammograms

Developmental Biology

Part 1: Introduction and developmental periods