History of Breast Cancer Screening 101 (Part I)

Hello bOObs Bloggettes:

Today we’ll look at a VERY brief and interesting review of the most important breast cancer (BC) screening studies and look at the back and forth discussions in the medical literature through the years.

The first study that set mammography’s controversy into motion was the “HIP study” — the only large, randomized control study carried out in the U.S. to-date — initiated in 1963. While a 15-year follow-up analysis of HIP showed a 23% reduction in breast cancer mortality, the benefits were noted in the 50 to 59 age group only — with no benefits for the 40 to 49 or 60 to 64 age groups. In fact, women in their 40s actually saw a slight increase in mortality, which sent mammogram advocates into a defensive tailspin.

Since the HIP study, many others have been carried out with differing results depending on the assumptions used for each study and the Conflicts of Interest involved, per arguing researchers. But notably, none of these studies were large, randomized control studies which is the Gold Standard for “Evidence-Based Medicine.”

The only other randomized study on mammography was conducted during the 1980s in Canada. The study’s researchers also carried out a 25-year follow-up study because the original Canadian study continued to cast serious doubt on mammography — mostly for women in their 40s but also for women in their 50s. Neither of these age groups showed any benefit from BC screening. In fact, women in the 40s showed an increase of 36% more BC deaths, which (as you can imagine) startled the screening world.

The 25-year Canadian Study follow-up also showed no decrease for BC mortality in women of ages 40 to 60, so the authors stood by their original findings. In fact, the researchers went so far as to conclude this: “Caution should be exercised when recommending mammographic screening to women before age 50.”

Wow. Strong words.

The 40 to 49 age group is such an important consideration for BC screening programs because those women are largely pre-menopausal and therefore have denser breasts. If you remember from my previous blogs, dense breast tissue (DBT) makes it harder for the radiologist to see any possible cancer as both DBT and tumors have a whitish hue on a mammogram X-ray — so they have to crank up the radiation during mammography to try and see through the DBT.

At the same time, the denser the breast, the higher the risk of BC for that woman — and the more susceptible they are to radiation-induced cancer from mammography in this radiation-sensitive tissue (see previous blog).

However, excluding women in their 40s from screening is not reasonable or practical because: 1) it’s not fair for these women to forego breast cancer screening, and 2) radiology and hospitals would lose a large chunk out of the billions of $$$ they’re making from mammograms — hence, the latter would have a collective fit.

We discussed in a previous blog that in 2009 the BC screening guidelines changed, advising women to get screened every other year at certain ages. This was due largely to over-diagnosis of DCIS but also because the two important studies mentioned above showed there were no lives saved overall for women in their 40s (in other words, as many women were being harmed as were being saved).

The infighting in the screening research community has been ongoing every since over what to do with women ages 40 to 49.

Well, how about using ultrasound instead, for starters: It’s better than mammography at picking up cancers in the higher categories of DBT anyway. Then thrown in thermography to catch any inflammation that might be settling in as a precursor to BC (see previous blog), and you have a much better strategy. Doesn’t that make more sense, ladies?

Meanwhile, the radiology associations are pushing to cast a wider net for women who are screened, advising that women at higher than average risk start screening at age 30 — but these women have even denser breasts and are therefore more susceptible to radiation-induced cancer. Not to mention the fact that (again) a mammogram is less likely to pick up cancer in DBT than an ultrasound.

So, where’s the logic?

Blog at you soon, thanks for reading and helping to spread the word!  (Please see the “share” links below.)  And we’d love to hear comments from you! (see below as well)

Stay healthy,

Megan

Megan Smith, M.S.
Director, bOObs: The War on Women’s Breasts

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