Lung cancer and heart attacks

Fascinating paper in this week’s BMJ by Michael Baum (click here).  We know mammography screening reduces breast cancer deaths slightly, but for every death prevented, about three women are unnecessarily treated with either breast removal, radiotherapy or both (click here and here). Although screening appears to have no effect on total mortality, enthusiasts argue that the trials were not large enough to demonstrate one.  Another explanation would be unnecessary treatment causing some other deaths.

Baum reminds us that the radiation given to 80% of the unnecessarily treated cases will cause lung cancer (relative risk 1.78) and, by damaging the internal mammary artery, myocardial infarction (RR 1.27).  He calculates that the additional deaths at least balance out the breast cancer deaths prevented, and at worst outweigh them three-fold.

So the advice should be.

Screening reduces breast cancer mortality.  But for every death prevented three women will have their breast unnecessarily removed or irradiated. The radiation will cause at least as many other deaths from lung cancer and heart attacks as the screening prevented. Maybe more. Still want it?

It won’t happen. There are too many vested interests keeping this racket going.

Baum is professor emeritus of surgery at University College London, was chief investigator of many key breast cancer trials, and knows what he’s talking about.

Jim Thornton