Unfortunately, the average person places far too much trust in the pronouncements of the medical establishment, not recognizing that these are simply opinions of a group of individuals. Those individuals are often considered to be experts, but therein lies the rub. Experts often hoe a narrow furrow. That is, they often possess a deep but narrow understanding, further exploring the terrain they began investigating many years ago. As an expert becomes more entrenched, the incentives to avoid deviating from the party line grow. First off, they created the party line, so they “own it” in an intellectual and emotional sense. Next, often someone else has something to gain economically, so they hire these experts. The expert now experiences a new level of “ownership” and has even less incentive to question his/her previous conclusions. Mistaken medical opinions erode slowly.
For decades we have “known” that mammograms and breast self-examination (BSE) are essential components of good preventive health care. Breast cancer has long been one of the major killers of women. We assumed that we fully understood the natural hsitory of breast cancers (i.e. how an untreated breast cancer changes over time and what it does to the woman). We assumed that we fully understood the risks of the screening. We assumed that finding these cancers early would improve the response to treatment, thereby saving the lives of as many women as possible. Mammography became established as THE medical screening, while BSE was the responsibility of each individual woman.
As I wrote long ago, BSE is clearly ineffective and actually associated with an increased likelihood of death from breast cancer. That seems totally wrong, but from very large and well-designed studies, we now know it to be true. As we continue to learn why our obvious assumption was wrong, our understanding of breast cancer grows in important ways. We now recommend “breast awareness”, i.e., seeking professional evaluation of any accidentally discovered lumps, but not actively looking for them.
The latest data continue to squeeze the dwindling confidence we have in mammograms.
The recent firestorm over recommendations that most women delay mammograms until age 50 and end them by age 70 was a consequence of critical evaluation of scientific data. The newer study adds fuel to that fire. This study included all women in Norway’s breast cancer screening and treatment program which began in 1996. It appears that bi-annual screening mammograms reduced the risk of dying from breast cancer by 3-4%. Dr Gilbert Welch noted in an editorial that this means that screening 2,500 women for 10 years would save one life. (BTW- I highly recommend his books for their simple and brilliantly clear discussions of how to understand statistical information about your health risks).
The risk reduction, in the age group at the greatest risk of breast cancer, is about 1/3 of what was previously accepted. The study also determined that 2/3 of the reduction in breast cancer deaths during the period was a result of improved treatment.
Most of the important studies on breast cancer screening have been coming from Scandinavia in recent years. Opposing their local rivals, a Swedish study released this week would appear to indicate that bi-annual screening of women in their 40’s reduces the risk of dying of breast cancer by 25%. However, a wide range of experts feel this study is badly tainted. As Dr. Otis Brawley of the American Cancer Society pointed out, these investigators overestimated the impact on death rates because they overlooked the fact that somewhere between 15 and 25% of breast cancers do not need any treatment.
Even those who view mammograms in the most positive light believe that the optimal combination of mammography, breast awareness (seeking evaluation when a breast lump is discovered accidentally) and the very best currently available treatment could reduce breast cancer deaths from roughly 54,000 a year down to 45,000 a year. That is a large number of survivors but still a small portion of all women affected. Mammograms are only part of the equation. While there is a place for mammography, we clearly need better breast cancer prevention, screening and treatment.