Bloggers love it when other bloggers cite them to support their arguments. I’m no different, as even a blinking Plexiglass box of lights likes to have its arguments appreciated. I particularly love it when a skeptical blogger uses some small thing I’ve written to refute particularly egregious nonsense. Unfortunately, there’s the flip side to this. There are times when I’d prefer I wasn’t cited. No, I’m not talking about anti-vaccinationists like J.B. Handley launching broadsides against me when I hit a particular nerve, various quacks or boosters of quackery going after me when, well, I hit a particular nerve, or pseudoscientists of all stripes attacking me because, well, I scored points against them. To me those are examples that validate what I’m doing; they mean I’m being effective.
What I don’t like is being cited to support a viewpoint that I most assuredly do not support and that, in fact, the post being makes it clear that I don’t support. In other words I hate it when I’m cited in such a way that makes it clear that the blogger doing the citing either didn’t read what I wrote and/or didn’t understand it. I’ve found just such an example citing my post from last week about the USPSTF’s new recommendations regarding mammography. A blogger named Susie Madrak completely missed the boat citing my work:
So I’m reading all these stories and saying, “Where’s the data about the risk from radiation?”
I finally found this important (and missing) piece of the puzzle in the San Francisco Chronicle:
Radiation causes 1 death for every 2,000 women screened annually starting at age 40, according to a study published in 2005 in the British Journal of Cancer. Another study shows that each mammogram increases the risk of breast cancer by 2 percent. Mammography also saves women’s lives, so that’s why it’s a trade-off.
Here’s some more info from Respectful Insolence, a medical research blog.
Got that? Statistically, some women have approximately as much chance of getting breast cancer from a mammogram as they have of it saving their lives. That’s why it’s considered a policy wash.
Yes, you might be one of those rare women saved by early detection. But you might also be someone who develops breast cancer from the yearly radiation exposure.
No, no, no, no. I said nothing of the sort. In fact, in the post cited, I didn’t even mention risks of secondary malignancy Interestingly, this same blogger has a different version of the same post that doesn’t cite me and has an even more overblown message:
Got that? Statistically, you have as much chance of getting breast cancer from a mammogram as you have of it saving your life. That’s why it’s considered a policy wash.
Yes, you might be one of those rare women saved by early detection. You ‘re
just as likely toalso might be someone who gets breast cancer from the yearly radiation exposure.
Where Ms. Madrak got the idea that my post said anything that supports her viewpoint, I have no idea. Although I like being cited as much as the next blogger, I don’t like it when my posts are used for a purpose opposite to my purpose and at odds with what I wrote. Even my more recent post, which explicitly addressed the issue of screening mammography and the risk of breast cancer from low dose radiation exposure wouldn’t give aid and comfort to Ms. Madrak’s misunderstanding of the issue.
As far as the San Francisco Chronicle referenced, the BJC article cited does indeed estimate 1 breast cancer death for every 2000 women screened modeling based on an excess relative risk model, which means that the risk of radiation-induced breast cancer was calculated relative to the estimated “underlying” incidence of breast cancer in the UK population. Moreover, the study also found that beginning mammographic screening of women between the ages of 40-49 may reduce the risk of dying of breast cancer by as much as 20%. Basically, the study concluded that if the reduction of the death rate due to breast cancer in a population that begins screening at age 40 is 20%, then the benefits in early diagnosis clearly outweigh the risks of a radiation-induced cancer from mammography, but if mammographic screening only reduces the risk by 10% then it’s close to a wash, with small or possibly no benefit.
As for the article referenced claiming that there is a 2% increase in the risk of cancer for each mammogram, I couldn’t find it. Moreover, another study suggest that the risk is 8 deaths from radiation-induced cancers for 100,000 women screened beginning at age 40. Meanwhile another study suggests that, for high risk BRCA carriers, weighing the relative risk of cancer from mammography, there would be “no net benefit from annual mammographic screening of BRCA mutation carriers at age 25-29 years; the net benefit would be zero or small at age 30-34 years, but there should be some net benefit at age 35 or older.” And these latter two are studies of young women, which, as I discussed the other day, are at higher risk from radiation-induced tumors to begin with.
Finally, another problem with a lot of these studies is that, because they have to span many years, they are looking at mammography as it was done 10, 20, or even 30 or more years ago. Back in those days, the radiation doses from mammography were much higher now, particularly compared to modern digital mammograms. These days, the dose of a standard screening mammogram is on the order of 0.7 mSv. (For comparison, typical radiation exposure from normal background radiation is around 2.5 mSv/year.)
So, to Ms. Madrak, I say, thanks but no thanks for your citation and incoming link. Next time, please read what I wrote and make sure you understand it before citing it in support of your ill-informed viewpoint.