Overdiagnosis of breast cancer at screening is clinically insignificant.

Long-term follow-up of randomized trials provide the most accurate estimates of overdiagnosis. Estimates from follow-up of service screening studies are almost as accurate if there is sufficient adjustment for lead time and risk status. When properly analyzed data from both of these types of trials indicate that the rate of overdiagnosis at screening mammography is clinically negligible: 0-5%. Population trend studies are a potentially highly inaccurate means to estimate overdiagnosis. Most cases of DCIS detected at screening are medium and high grade with substantial potential to become an invasive disease. To avoid overtreatment, clinicians need to tailor their treatment of DCIS to the histologic and molecular characteristics of each case.