Evidence That BRCA1- or BRCA2-Associated Cancers Are Not Inevitable

Table 1 Rates of spontaneous SCE determined by BrdU in normal human lymphocyte cultures differ among laboratories but increase greatly in response to exogenous mutagens.

Reference	Spontaneous SCEs ± SD per cell determined by BrdU; n	Test mutagen	SCEs ± SD (max)/cell with mutagen; n	Two-sample unpaired t test results, mutagen SCEs versus spontaneous SCEs
43	7.01 ± 1.24; 22	Chemotherapy	11.52 ± 3.33; 24	P < 0.001
44	5.175 ± 0.607; 31	Chlormethine hydrochloride^a	18.433 ± 4.523; 10	P < 0.001
45	8.4 ± 0.11; 5	Ptaquiloside	26.1 ± 0.14; 5	P < 0.001
46	2.54 ± 0.82; 20	Type 1 diabetes	5.44 ± 1.47; 35	P < 0.001
47	21.84 ± 4.21; 20	White fluorescent light in S phase	28.37 ± 5.98	P = 0.0003
48	6.9 ± 0.9; 22	Smoking	8.4 ± 1.2; 18	NS
49	7.16 ± 1.13; 15	Smoking	8.65 ± 1.43; 14	NS
50	9.32 ± 1.0; 8	Smoking	10.76 ± 1.36; 6	NS
51	4.70 ± 0.24; 2 4.48 ± 0.46; 2	MMC^b	34.82 ± 1.25; 2	P < 0.0001 for weighted
52	4.45 ± 0.68; 4	MMC^b	53.37 ± 5.1; 4	averages of SCEs
53	5.95 ± 0.31; 1		25.95 ± 0.81; 1	from MMC versus
	6.40 ± 0.59; 1 6.64 ± 0.47; 1	MMC	23.52 ± 1.30; 1	SCEs in control cells (51–53)

n, Number of subjects; NS, not statistically significant.
^aAdded to cells as a positive control mutagen.
^bMMC greatly increased the frequency of chromosomal aberrations as independent supporting evidence.

ISSN: 1528-3658