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

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. 