. 2019 Nov 14;6(1):68–74. doi: 10.1001/jamaoncol.2019.3876

Table 1. Risk-Adapted Starting Age of Screening by Family History of Breast Cancer and Age at Diagnosis of Youngest Affected First-Degree Relative.

Family History	Youngest Age at Diagnosis in FDRs, y	No. of Patients	Risk-Adapted Starting Age of Screening, y
Whole population	NA	118 953	40^a	45^a	50^a
No family history	NA	102 751	41	46	52
0 FDR + 1 SDR	NA	2512	37	42	45
0 FDR + ≥2 SDRs	NA	276	36	39	41
1 FDR + 0 SDR	All ages	12 075	35	38	40
	<40	691	30	34^b	36
	40-44	916	32	36	38
	45-49	1426	34	37	39
	≥50	9042	36	39	41
1 FDR + ≥1 SDRs	All ages	544	32	36	38
	<40	55	23	25	26
	40-49	123	32	35	37
	≥50	366	34	37	38
≥2 FDRs + ≥0 SDRs	All ages	795	28	32	35
	<50	449	23	26	27
	≥50	346	33	35	36
10-y Cumulative risk in the general population, %	NA	NA	1.1	1.8^b	2.2

Abbreviations: FDR, first-degree relative; NA, not applicable; SDR, second-degree relative.

^{^a}

Ages 40, 45, and 50 years are recommended (benchmark) by the guidelines as the starting age of mass screening. Other ages are evidence-based risk-adapted starting age of screening recommended by the present study.

^{^b}

Example: When screening for women with average risk is recommended at age 45 years (10-year cumulative risk of 1.8%), women with 1 FDR who received a diagnosis before age 40 years reached the same level of risk at age 34 years, 11 years earlier than her peers in the general population.