by Anthony B. Miller, MD, FRCP. Professor Emeritus, Dalla Lana School of Public Health, University of Toronto
When the 25-year report of the Canadian National Breast Screening Study (CNBSS) was published , showing no benefit from mammography screening, there was much dissension, and attempts to show that what we reported could not be true [2,3], to which we responded . The belief that “early” detection of a cancer is bound to be beneficial is entrenched in our society, people do not understand that the mere early detection of a cancer does not automatically result in benefit, the cancer may not have been destined to be fatal with modern therapy even when detected later by the woman herself, the cancer might never have progressed to become detectable by the woman if it had not been revealed by the mammogram, or, the cancer was destined to kill whatever stage it was detected because of its innate biology. Even if we accept that mammography screening reduces breast cancer mortality by 15-20% , and I do not, that means that 80% or more of the deaths from breast cancer destined to occur will still do so.