Risk of invasive breast cancer in relatives of patients with breast carcinoma in situ: a prospective cohort study

Table 3 Relative risk of breast cancer for family members of patients with invasive and in situ breast tumor by period before and after nationwide coverage with mammography screening

		Age at breast cancer diagnosis in index woman (years)
Period	Family history	All ages			< 50			≥ 50
Period	Family history	N	SIR	95% CI	N	SIR	95% CI	N	SIR	95% CI
1958–2015^a	No family history	102,177	Reference		31,693	Reference		70,484	Reference
	1 FDR with in situ	575	1.5	1.4–1.7	126	1.6	1.3–1.9	449	1.5	1.4–1.7
	1 FDR with invasive	11,990	1.7	1.7–1.8	2874	2.0	1.9–2.1	9116	1.7	1.6–1.7
1958–1994^b	No family history	21,139	Reference		14,113	Reference		7026	Reference
	1 FDR with in situ	42	2.0	1.5–2.8	24	1.9	1.2–2.8	18	2.3	1.3–3.6
	1 FDR with invasive	1381	1.9	1.8–2.0	884	1.9	1.8–2.0	497	1.8	1.6–1.9
1995–2015^c	No family history	81,038	Reference		17,580	Reference		63,458	Reference
	1 FDR with in situ	533	1.5	1.4–1.6	102	1.5	1.2–1.8	431	1.5	1.4–1.7
	1 FDR with invasive	10,609	1.7	1.7–1.7	1990	2.0	2.0–2.1	8619	1.6	1.6–1.7

All SIRs were adjusted for age, socio-economic status, period, and region
FDR first-degree relative, SIR standardized incidence ratio, CI confidence interval
^aEntire period screening
^bBefore and during scale up of mammography
^cAfter nationwide coverage of mammography screening

ISSN: 1741-7015