I. Definition, purpose and classification of breast cancer screening
1. Tumor screening, or screening, is a cancer prevention measure for asymptomatic people, while medical examination for symptomatic people is called diagnosis.
2.Breast cancer screening is an effective, simple and economical breast examination measure to screen asymptomatic women for early detection, early diagnosis and early treatment. Its ultimate goal is to reduce the mortality rate of breast cancer in the population.
3. Screening: There are two types of screening: opportunistic screening and group screening. Opportunistic screening is an individual woman’s initiative or voluntary visit to a medical institution that provides breast screening; group screening is an organized community or unit entity that provides breast screening for women of appropriate age.
The starting age for women to participate in breast cancer screening
Generally, opportunistic screening is recommended to start at the age of 40, but for some high-risk groups, the starting age of screening can be advanced to 20.
The age of free breast cancer screening for rural women conducted by the Ministry of Health is 35-65 years old, with ultrasound examination as the main screening age, supplemented by mammography.
Measures used for breast cancer screening
1. Mammography
(1) The role of mammography in reducing breast cancer mortality in women over 40 years old has been recognized by most foreign scholars.
(2) It is recommended that each breast should be routinely taken in two positions, i.e. cephalopodial (CC) and lateral oblique (MLO) positions.
(3) Mammogram images should be independently reviewed by two or more specialized radiologists.
(4) Mammography screening is highly accurate in Asian women over 40 years of age. However, mammography does not penetrate well into young dense breast tissue, so mammography is generally not recommended for women under 40 years of age without clear risk factors for breast cancer or abnormalities found on clinical examination.
(5) The radiation dose of routine mammography is low and not harmful to women’s health, but normal women do not need to have repeated mammograms in a short period of time.
2.Clinical examination of the breast
(1) Clinical breast examination is not effective as a screening method for breast cancer alone, and there is no evidence that it can improve the early diagnosis rate and reduce the mortality rate of breast cancer.
(2) It is generally recommended to use physical examination as a combined screening measure for breast screening, which may compensate for the omission of mammography screening.
3.Self-examination of breast
(1) Breast self-examination cannot improve the detection rate of early diagnosis of breast cancer and reduce the mortality rate.
(2) Since it can raise women’s awareness of cancer prevention, primary health care workers are encouraged to teach women the method of breast self-examination once a month, and premenopausal women should be advised to perform it 7-10 days after menarche.
4. Ultrasound examination of the breast
It can be used as a combined screening test with mammography screening or as a supplemental test for those with BI-RADS level 0 mammography screening. Ultrasound can be used as an adjunct to breast screening because the Chinese population has a higher incidence of breast cancer, a higher percentage of premenopausal patients, and a relatively dense breast.
5.Magnetic resonance imaging (MRI) of the breast
(1) MRI examination can be used as a supplement to mammography, clinical examination of the breast or ultrasound examination of the breast in suspected cases.
(2) It requires high equipment requirements, is expensive and time-consuming, and requires intravenous injection of enhancer.
(3) It can be used in combination with mammography for breast cancer screening in certain groups with high risk of breast cancer.
6.Other tests
The current evidence does not support the use of near-infrared scan, nuclear scan and ductal lavage as breast cancer screening methods.
Breast cancer screening guidelines for general population
1. 20-39 years of age
Breast screening is not recommended for non-high risk groups.
2. 40-49 years old
(1) Opportunistic screening is appropriate.
(2) One mammogram per year.
(3) Recommended in combination with clinical examination.
(4) Combination with ultrasound is recommended for dense breasts.
3. 50-69 years old
(1) Suitable for opportunistic screening and population screening.
(2) Mammogram every 1 to 2 years.
(3) Combined with clinical examination is recommended.
(4) Combination with ultrasound is recommended for dense breasts.
4. 70 years of age or older
(1) Opportunistic screening is appropriate.
(2) Mammogram every 2 years.
(3) Combination with clinical examination is recommended.
(4) Combination with ultrasound is recommended for dense breasts.
V. Screening for high-risk groups of breast cancer
In addition to clinical examination, B-ultrasound and mammography, new imaging methods such as MRI can be used.
Definition of high-risk group for breast cancer
(1) Those who have a clear genetic predisposition to breast cancer (see Appendix I for details).
(2) Patients with previous ductal or lobular moderate to severe atypical hyperplasia or lobular carcinoma in situ.
(3) Patients with previous history of chest radiotherapy.