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December 1, 2004

Spontaneous Regression of Cancerous Tumors Detected by Mammography Screening—Reply

Author Affiliations

Letters Section Editor: Robert M. Golub, MD, Senior Editor.

JAMA. 2004;292(21):2579-2580. doi:10.1001/jama.292.21.2580-a

In Reply: Dr Zahl and colleagues suggest that as many as one third of all cancerous tumors detected by mammography screening among women aged 50 to 69 years would not have been detected during the individual’s lifetime without screening, and therefore represent overdiagnosis.1 They suggest further that many subclinical cancerous tumors, invasive and noninvasive, may regress spontaneously without treatment. They base this hypothesis on the high breast cancer detection rates in the screened cohorts of women compared with nonscreened cohorts, the absence of a substantial and durable decline in detection rates following screening, and the time trends of breast cancer incidence rates that increase markedly (as much as 50%) in the screened cohorts after initiation of population-based mammography screening. A strong tendency of many of the tumors detected by mammography screening to undergo apoptosis and even regress spontaneously would be consistent with a favorable outcome of cancerous tumors of similar size found outside of screening.

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