lumclogo.gif (1964 bytes)Prevalence of BRCA1 among a retrospectively collected series of 642 breast cancer cases

This work was published by Papelard et al. (2000). The prevalence of disease-related BRCA1 mutations was investigated in 642 Dutch breast cancer patients not selected for family history or age at diagnosis. Cases were collected consecutively in the Leiden Academic Hospital during 1984-1996. BRCA1 was screened for mutations using a DSDI-test which would pick up ~70% of the currently known Dutch BRCA1 mutation spectrum (including the major founder deletions).

Table 1: Frequency of disease-related BRCA1 mutations by age-group

Age group Number tested Proportion of total Mutation positive (%) Expected % 
(Ford et al, 1995)
20-29 5 0.008 0 - 7.5
30-39 51 0.079 4 7.8 5.1
40-49 154 0.240 6 3.9 2.2
50-59 158 0.246 0 - 1.4
60-69 128 0.199 0 - 0.8
70+ 147 0.227 0 - -
Totals 642 1.000 10 1.6 1.7

Data on family history of cancer was available from 6 mutation carriers, who filled in questionnaires. Two carriers had died, and two did not return the questionnaires. From the latter four, family history data were restricted to medical records and hence limited to breast cancer that developed in relatives prior to the diagnosis of the case. Five out of 10 carriers had a first- or second degree relative with breast cancer.

Table 2: Family history of breast and ovarian cancer in the 10 mutation carriers

Case Number of 1st-degree relatives with breast (br) or ovarian (ov) cancer Number of 2nd-degree relatives with breast (br) or ovarian (ov) cancer Total number of 1st/2nd-degree female relatives
MC1 0 2 ov 2/5
MC2 1 br 1 br 4/6
MC3 0 2 br 2/11
MC4 0 0 1/6
MC5 1 br, 1 ov 3 br 2/7
MC6 1 br 0 4/3
MC7 0 0 br, ? ov unknown
MC8 0 0 br, ? ov unknown
MC9 0 br, ? ov 0 br, ? ov unknown
MC10 0 br, ? ov 0 br, ? ov unknown

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