Table 2 Base-case probabilities and sensitivity analysis parameter estimates

Parameters	High risk [sensitivity estimates]	Moderate risk [sensitivity estimates]
Mutation prevalence	18% (Stoppa-Lyonnet et al, 1997) [7% (Couch et al, 1997; Stoppa-Lyonnet et al, 1997), 27% (Eccles et al, 1998)]
Mutation penetrance	BRCA1/2	25%^a [17%, 33%]^c
	82% (Easton et al, 1993) [70%^a, 82%]
	Unidentified mutation
	40%^a [35%, 40%]^a
Prophylactic mastectomy	5%^c [5%^c, 38%^d]	0%^c
Prophylactic oophorectomy	5%^c [0%^c, 14%^d]	0%^c
Prophylactic mastectomy and oophorectomy	5%^c [0%^c, 13%^d]	0%^c
5 year death rate for genetics service patients	35 – 54 years 7.8% – 2 year lead time [3.8% with no lead time, 9.4% with a 2 year lead time]^b	35–54 years 7.8% – 2 year lead time [3.8% with no lead time, 9.4% with a 2 year lead time]^b
	55 – 59 years 11.5% – 2 year lead time [6.9% with no lead time, 16.7% with a 2 year lead time]^b	55 – 59 years 11.5%-2 year lead time [6.9% with no lead time, 16.7% with a 2 year lead time]^b
5 year death rate for nongenetics service patients	35 – 54 years 28.4%^b [24.4%, 35.1%) – no lead time^b	35–54 years 28.4%^b [24.4%, 35.1%] – no lead time^b
	55 – 59 years 34.9% [30.2%, 39.0%] – no lead time^b	55 – 59 years 34.9% [30.2%, 39.0%] – no lead time^b
Number of Markov cycles/years	24 [15, 24]	19 [9, 19]

^aPDP Pharoah (personal communication, 2002).
^bH Beer and H Fielder, Breast Test Wales (personal communication, 2002).
^cEstimated by this research team.
^dUp to 35 – 51% of women at increased risk of developing breast cancer (Hatcher et al, 2001; Meijers-Heijboer et al, 2003) have been found to have prophylactic mastectomy and 27 – 49% (Meijers-Heijboer et al, 2003; Schwartz et al, 2003) of women at increased risk of developing ovarian cancer have opted to have prophylactic oophorectomy. As this model deals solely with women with a family history of breast cancer, we estimated that a maximum of 51% of women will have mastectomy (38% mastectomy alone +13% mastectomy and oophorectomy) and 27% will have oophorectomy (14% oophorectomy alone +13% mastectomy and oophorectomy).

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