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Table 2 Probability of cancer detection at prevalent and incident screens, andmonthly incidence of interval cancers.

From: Modelling the overdiagnosis of breast cancer due to mammography screening in womenaged 40 to 49 in the United Kingdom

Description Parameter Definition
Any screen k   
Number of women screened n.scr k see Table 1
Negative screening episodes n.neg k n .sc r k ( 1 - P .sc r n p i s k - P .sc r p i s k - P .sc r i n v k )
Proportion of false negatives at screen k  
False negative NPIS P .fne g n p i s k ( P .sc r n p i s k n .sc r k ( 1 - S i s ) / S i s ) / n .ne g k
False negative PIS P .fne g p i s k ( P .sc r p i s k n .sc r k ( 1 - S i s ) / S i s ) / n .ne g k
False negative PIBC P .fne g i n v k ( P .sc r i n v k n .sc r k ( 1 - S i n v ) / S i n v ) / n .ne g k
Any pre-cancer state P .fne g k P .fne g n p i s k + P .fne g p i s k + P .fne g i n v k
Prevalent screen   
Screen-detected NPIS P .sc r n p i s 1 S is P12(age)/(P11(age)+ P12(age) + P13(age) +P14(age))
Screen-detected PIS P .sc r p i s 1 S is P13(age)/(P11(age)+ P12(age) + P13(age) +P14(age))
Screen-detected PIBC P .sc r i n v 1 S inv P14(age)/(P11(age)+ P12(age) + P13(age) +P14(age))
Incident screen k   
Screen-detected NPIS P .sc r n p i s k S i s ( 1 - P .fne g k - 1 ) P 12 ( t ) + P .fne g n p i s k - 1 P 22 ( t )
Screen-detected PIS P .sc r p i s k S i s ( 1 - P .fne g k - 1 ) P 12 ( t ) + P .fne g n p i s k - 1 P 22 ( t )
Screen-detected PIBC P .sc r i n v k S i n v ( 1 - P .fne g k - 1 ) P 14 ( t ) + P .fne g p i s k - 1 P 34 ( t ) + P . fne g i n v k - 1 P 44 ( t )
Monthly incidence of interval cancers in the first m months after screen k
In-situ I C i s k n .ne g k ( P 11 ( m - 1 ) P 16 ( 1 ) + P 12 ( m - 1 ) P 26 ( 1 ) ) + P .sc r i s k n .sc r k ( 1 - S i s ) / S i s ( P 22 ( m - 1 ) P 26 ( 1 ) )
Invasive I C i n v k n .ne g k ( P 11 ( m - 1 ) P 15 ( 1 ) + P 13 ( m - 1 ) P 35 ( 1 ) + P 14 ( m - 1 ) P 45 ( 1 ) ) + P .sc r i n v k n .sc r k ( 1 - S i n v ) / S i n v ( P 44 ( m - 1 ) P 45 ( 1 ) ) + P .sc r p i s k n .sc r k ( 1 - S i s ) / S i s ( P 34 ( m - 1 ) P 45 ( 1 ) + P 33 ( m - 1 ) P 35 ( 1 ) )
  1. Age, age at first screen; NPIS, non-progressive in situ breastcancer; PIBC, preclinical invasive breast cancer; PIS, progressive insitu breast cancerl; t, screening interval.