Table 4.

Frequencies of CBC patients carrying apathogenic DNA-damage repair pathway mutation

Age (years)	All CBC patients		Previous RT		No RT		Carriers versus non-carriers
	n	Percentage	n	Percentage	n	Percentage	OR for CBC after RT	95% CI
<40 (n = 91)	22/91	24	19/67	28	3/24	12	2.77	0.74–10.39
40–50 (n = 156)	29/156	18.6	22/102	21.6	7/54	12.9	1.85	0.73–4.65

Results for all contralateral breast cancer (CBC) patients, and patients stratified by previous radiation exposure, are presented, according to age at diagnosis of first primary breast cancer (before the age of 40 years or between 40 and 50 years of age). Odds ratio (OR) and 95% confidence interval (CI) are given for mutation carriers versus non-carriers to develop radiation-associated breast cancer. RT, radiation treatment.