Re: Harms from breast cancer screening outweigh benefits if death caused by treatment is included
Proponents of informed decision-making should offer simple numbers for women to remember. We provide a transparent alternative supporting Dr. Baum’s benefit analysis in Box 1.1 Previously we estimated the screen-free breast cancer death risk from U.S. SEER data by comparing the 1980 and 2004 age-specific cumulative breast cancer death risks over 15 years.2 We adjusted for roughly equal contributions of screening mammography and modern therapy in decreasing the risk, including a 10-year window.3 However, it is now clear that mammography has contributed much less than therapy, given the rate of advanced cancers has not decreased in screened populations, and younger women not eligible for screening have had greater mortality decreases than older groups with screening.4
Assuming that 25% of the mortality decrease results from screening yields the screen-free death risk in column 5. A 50 year-old woman has a 995/1000 or 99.5% chance of not dying from breast cancer over 10 years without screening:
After calculating the absolute risk reduction, the number needed to invite for routine (multiple) screening mammograms to extend one life is 500-5000, depending on the assumed RRR and the follow-up time. Explaining that about 1000 women need to endure routine screening (about 3-4 mammograms each in the UK, double in the US) to let one woman win the screening lottery is easy to remember. The harm of overtreatment, about 5 women/1000 at 30% overdiagnosis, will increase with actual screening participation.5 Ironically, mammography results in massively increased breast cancer incidence and earlier death for some women, as Dr. Baum has calculated.
1. Baum M. Harms from breast cancer screening outweigh benefits if death caused by treatment is included. BMJ 2013;346:f385.
2. Keen JD, Keen JE. What is the point: will screening mammography save my life? BMC Med Inform Decis Mak 2009;9:18.
3. Keen JD. Promoting screening mammography: insight or uptake? J Am Board Fam Med 2010;23(6):775-82.
4. Jorgensen KJ, Keen JD, Gotzsche PC. Is mammographic screening justifiable considering its substantial overdiagnosis rate and minor effect on mortality? Radiology 2011;260(3):621-7.
5. Gotzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2011(1):CD001877.
Rapid Response:
Re: Harms from breast cancer screening outweigh benefits if death caused by treatment is included
Proponents of informed decision-making should offer simple numbers for women to remember. We provide a transparent alternative supporting Dr. Baum’s benefit analysis in Box 1.1 Previously we estimated the screen-free breast cancer death risk from U.S. SEER data by comparing the 1980 and 2004 age-specific cumulative breast cancer death risks over 15 years.2 We adjusted for roughly equal contributions of screening mammography and modern therapy in decreasing the risk, including a 10-year window.3 However, it is now clear that mammography has contributed much less than therapy, given the rate of advanced cancers has not decreased in screened populations, and younger women not eligible for screening have had greater mortality decreases than older groups with screening.4
Assuming that 25% of the mortality decrease results from screening yields the screen-free death risk in column 5. A 50 year-old woman has a 995/1000 or 99.5% chance of not dying from breast cancer over 10 years without screening:
After calculating the absolute risk reduction, the number needed to invite for routine (multiple) screening mammograms to extend one life is 500-5000, depending on the assumed RRR and the follow-up time. Explaining that about 1000 women need to endure routine screening (about 3-4 mammograms each in the UK, double in the US) to let one woman win the screening lottery is easy to remember. The harm of overtreatment, about 5 women/1000 at 30% overdiagnosis, will increase with actual screening participation.5 Ironically, mammography results in massively increased breast cancer incidence and earlier death for some women, as Dr. Baum has calculated.
1. Baum M. Harms from breast cancer screening outweigh benefits if death caused by treatment is included. BMJ 2013;346:f385.
2. Keen JD, Keen JE. What is the point: will screening mammography save my life? BMC Med Inform Decis Mak 2009;9:18.
3. Keen JD. Promoting screening mammography: insight or uptake? J Am Board Fam Med 2010;23(6):775-82.
4. Jorgensen KJ, Keen JD, Gotzsche PC. Is mammographic screening justifiable considering its substantial overdiagnosis rate and minor effect on mortality? Radiology 2011;260(3):621-7.
5. Gotzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2011(1):CD001877.
Competing interests: No competing interests