The grades of evidence (I-III) and levels of recommendations (A-C) are defined at the end of the "Major Recommendations."
The following recommendations are based on limited and inconsistent scientific evidence (Level B):
- Women aged 40 to 49 years should have screening mammography every 1 to 2 years.
- Women aged 50 years and older should have annual screening mammography.
The following recommendations are based primarily on consensus and expert opinion (Level C):
- Despite a lack of definitive data for or against breast self-examination, breast self-examination has the potential to detect palpable breast cancer and can be recommended.
- All women should have clinical breast examinations annually as part of the physical examination.
Definitions:
Grades of Evidence
I Evidence obtained from at least one properly designed randomized controlled trial
II-1 Evidence obtained from well-designed controlled trials without randomization
II-2 Evidence obtained from well-designed cohort or case-control analytic studies, preferably from more than one center or research group
II-3 Evidence obtained from multiple time series with or without the intervention. Dramatic results in uncontrolled experiments also could be regarded as this type of evidence.
III Opinions of respected authorities, based on clinical experience, descriptive
studies, or reports of expert committees
Levels of Recommendations
Level A - Recommendations are based on good and consistent scientific evidence.
Level B - Recommendations are based on limited or inconsistent scientific evidence.
Level C - Recommendations are based primarily on consensus and expert opinion.