S2. Guidelines for breast cancer screening from U.S. Preventive Services Task Force.

Years	40−49 years old	50−74 years old	≥75 years old	References
2002	Screening with intervals of 1−2 years	Screening with intervals of 1−2 years	Screening with intervals of 1−2 years	(30). Ann Intern Med 2002;137:344-6.
2009	Do not screen routinely. Individualize decision to begin biennial screening according to the patient’s context and values	Screen every 2 years	No recommendation	(31). Ann Intern Med 2009;151:727-37.
2016	The decision to start screening should be an individual one	Screen every 2 years	No recommendation	(32). Ann Intern Med 2016;164:279-96.