I wrote saying this very thing several years ago, and I couldn’t believe how much I was attacked. People really buy into that whole “early detection saves lives” slogan. But it doesn’t, as this study shows:
More than twenty-five years ago, 89,835 women between the ages of 40-59 were randomized to either get annual screening with mammography for five years or no mammography. I can imagine some of you are gasping in horror. After all, how could we possible not give women annual mammograms. Wouldn’t that be malpractice?
Of the 44,925 women in the mammogram group, 500 died of breast cancer. Of the 44, 910 in the no mammogram group, 505 died of breast cancer. This was not a significant difference. There wasn’t a significant difference if you looked at only older women (50-59) or younger women (40-49). There wasn’t a difference if you lengthened the screening period to seven years.
Mammograms did not affect mortality at all.
However, they did affect diagnosis. During the screening period, 666 cases of cancer were diagnosed in the mammography group versus 524 in the no mammography group. This meant an excess of 143 breast cancers were diagnosed with screening. Fifteen years later, the excess settled in at 106 cases of cancer.
More than 20% of the cancers detected by mammography were over-diagnosed. This means that mammography over-diagnosed one case of breast cancer for every 424 women screened with mammography. Do you know how many women we screen a year here?
This study is going to make a whole lot of people upset. It’s a large, well designed randomized control trial with a really long follow-up period. The people in the mammogram groups actually complied with screening in surprisingly high numbers. It’s hard to find fault with much of this. The data make a really good case that universal screening with mammograms does almost no good, and likely does harm.
Oh, they did find that the 25-year survivial rate was significantly better in the mammogram group (even if mortality wasn’t). But you all know why, right?
Although the difference in survival after a diagnosis of breast cancer was significant between those cancers diagnosed by mammography alone and those diagnosed by physical examination screening, this is due to lead time, length time bias, and over-diagnosis.
I don’t know why they kept saying that slogan when anyone with a high school education (at least as far as science goes) would know that radiation CAUSES cancer, that there isn’t any “minimum dose” that isn’t harmful and that all radiation exposure is cumulative – it doesn’t go away.
I do 3D scientific visualization for a living, and I’ve worked with a lot of CT & MRI data. Using a 2D scanning technique on a 3D squashy tissue is bloody stupid, and irradiating it at the same time is even worse.
My doctor has reduced my mammograms to every other year. My family has no history on either side. She also said I am out of the younger age group that gets aggressive cancers. I have also read that it has been determined by some oncologists that some cancers require monitoring, not treatment, as they can be “self correcting” and don’t require chemo or surgery. My fear is about “over treatment” not missed diagnosis. I have witnessed some women’s side effects, including horrible infections that were very difficult to treat. There are many that disagree with this and I can understand why, due to a relative being ill or a personal positive screening.