In recent decennia, mammography screening has been introduced in many countries. There are ongoing debates on whether screening does more harm than good and on the related optimization of screening strategy. We cannot measure sensitivity directly as there are no methods to determine the amount of asymptomatic cancers that are detectable by screening. What is remarkable about the findings of their studies is that the sensitivity is 100% for tumors varying in size from 15 to 20 mm and over. The studies have shown that even tumors larger than 50 mm can be invisible on mammography.

 In this study, the tumor volume doubling time for women aged 50–70 years old was on average 157 days. The data from the first screening round was excluded as it is well known that in the first screening round relatively more and larger tumors are found compared to the subsequent screening rounds. The time between the diagnosis of an interval cancer which had a possible false-negative result in the previous one or two screenings rounds was therefor set at 502 and 1232 (two years plus 502 days) days respectively. The tumor volume doubling time was set to the lower and upper bounds of the 95% confidence interval (CI), which were 121 days and 204 days respectively.

As a result we can say that, for screen-detected cancers, the mean diameter and corresponding standard deviation (mm) were 14.0 (95%CI: 10.6–18.4) and 1.93 (95%CI: 1.52–2.46), while for interval cancers, these were 20.9 (95%CI: 18.5–23.8) and 1.77 (95%CI: 1.58–1.95), respectively.

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