BMJ  2006;332:727 (25 March), doi:10.1136/bmj.332.7543.727-a

Letter

Ramifications of screening for breast cancer

Overdiagnosis in the Malmö trial was considerably underestimated

The first 150 words of the full text of this article appear below.

EDITOR—Updated results from the Malmö mammography screening trial have suggested that screening caused an over-diagnosis of breast cancer of 10% in women aged 55-69 years at randomisation.¹ The authors noted that evidence from randomised trials on the level of overdiagnosis was lacking. This is not correct. On the basis of data from the Malmö trial,² and the two trials from Canada,³ we have previously estimated a level of overdiagnosis of 30% (mean follow-up 8.8 years and 7 years, respectively)⁴ and have also suggested an over-diagnosis of 33% in the other Swedish trials, based on number of cancers identified before the control group was screened.⁵

Zackrisson et al followed up the women for an additional 15 years after the trial ended and noted that they could have underestimated the level of overdiagnosis as some asymptomatic women in the control group received mammography. They did not quantify this, but in . . . [Full text of this article]

Nordic Cochrane Centre, Rigshospitalet, DK-2100 Copenhagen Ø, Denmark pcg@cochrane.dk

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Rate of over-diagnosis of breast cancer 15 years after end of Malmö mammographic screening trial: follow-up study

Sophia Zackrisson, Ingvar Andersson, Lars Janzon, Jonas Manjer, and Jens Peter Garne
BMJ 2006 332: 689-692. [Abstract] [Full Text] [PDF]