Table 4. Standardised incidence ratio (SIR) and absolute excess risk (AER) for all second cancers diagnosed 1972–2003 following BCIS (breast carcinoma in situ) in southern Netherlands, according to women's characteristics at the time of BCIS diagnosis.

		Second breast cancer				Second other cancers
Characteristic	PYRa	Obsb	Expc	SIR	AER	Obsb	Expc	SIR	AER
Age at diagnosis
≤49 years	2334	20	4.9	4.0d	65	10	6.6	1.5	15
≥50 years	4204	41	13.1	3.1d	66	42	29.8	1.4d	29
Treatment
No Radiotherapy	4474	39	12.4	3.1d	59	29	25.2	1.1	8
With Radiotherapy	2064	22	5.6	3.9d	79	23	11.1	2.1e	57
Subtype of initial cancer
DCIS	6106	58	16.8	3.4d	67	47	34.3	1.4d	21
LCIS	432	3	1.2	2.5	42	5	2.1	2.4	67
Time of diagnosis e
1972–1992	2708	24	7.0	3.4d	63	17	14.4	1.2	9
1993–2002	3830	37	11.0	3.4d	68	35	21.9	1.6d	34

^aPYR: person-years.

^bObs: observed numbers of second primary cancers.

^cExp: expected numbers of second primary cancers.

^d95% confidence interval excludes 1.

^eBreast cancer screening in southern Netherlands began to have impact in 1993 (Fracheboud et al, 2004).