1.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 to screen asymptomatic women for early detection, early diagnosis and early treatment through effective, easy and economical breast screening measures. Its ultimate goal is to reduce the mortality rate of breast cancer in the population.
There are 2 types of screening: opportunistic screening and mass screening. Opportunistic screening is a medical institution that provides breast screening for women on their own initiative or voluntarily; mass screening is a community or unit entity that provides breast screening for women of appropriate age in an organized manner.
2. The starting age for women to participate in breast cancer screening
(1) Opportunistic screening is generally recommended to start at the age of 40, but for some people with high risk of breast cancer, the starting age of screening can be advanced to 20.
(2) There is no recommended age for group screening, and any group screening conducted in China is at the research stage, and there is a lack of data on cost-benefit analysis of different ages. The age of free breast cancer screening for rural women conducted by the Ministry of Health is 35-65 years old, and ultrasound examination is used mainly to supplement mammography.
3. Measures used for breast cancer screening
3.1 Mammography
(1) The role of mammography in reducing breast cancer mortality in women over 40 years of age has been recognized by most scholars abroad.
(2) It is recommended that 2 body positions should be routinely taken for each breast, namely cephalopodial (CC) and lateral oblique (MLO) positions.
(3) Mammogram images should be independently reviewed by 2 or more specialized radiologists.
(4) Mammography screening is highly accurate in Asian women over 40 years of age. However, mammography has poor penetration to young dense breast tissues, therefore, mammography is generally not recommended for women under 40 years of age without clear risk factors for breast cancer or abnormalities found on clinical physical examination.
(5) Routine mammography is not harmful to women’s health because of its low radiation dose, but normal women do not need to undergo repeated mammograms in a short period of time.
3.2 Breast clinical examination
(1) Clinical breast examination is not effective as a screening method for breast cancer alone, and there is no evidence that this method improves the early diagnosis of breast cancer and reduces mortality.
(2) Physical examination is generally recommended as a combined screening measure for breast screening and may compensate for missed mammography screening.
3.3 Breast self-examination
(1) Breast self-examination does not improve the detection rate of early diagnosis of breast cancer and reduce mortality.
(2) Since it can raise women’s awareness of cancer prevention, primary health care workers are still encouraged to teach women the method of breast self-examination once a month, and premenopausal women should be recommended to choose 7-10 days after menstruation.
3.4 Breast ultrasound can be used as a combined screening measure with mammography screening or as a complementary screening measure for those with BI-RADS grade 0 mammography screening results. Given that the Chinese population has a higher peak incidence of breast cancer, a high proportion of premenopausal patients, and a relatively dense breast, ultrasound can be used as an adjunct to breast screening.
3.5 Magnetic resonance imaging (MRI) of the breast
(1) MRI examination can be used as a supplemental examination measure for suspected cases detected by mammography, clinical breast examination or breast ultrasound examination.
(2) It requires high equipment requirements, is expensive, is time-consuming to examine, and requires intravenous injection of enhancer.
(3) It can be used in combination with mammography for breast cancer screening in certain breast cancer high-risk groups.
3.6 Other examinations Current evidence does not support near-infrared scan, nuclear scan, ductal lavage and other examinations as breast cancer screening methods.
4. Breast cancer screening guidelines for women in the general population
4.1 Breast screening is not recommended for non-high-risk groups between the ages of 20-39 years.
4.2 40-49 years of age
(1) Opportunistic screening is appropriate.
(2) 1 mammogram per year.
(3) Recommended in conjunction with clinical physical examination.
(4) Combination with ultrasound is recommended for dense breasts.
4.3 50-69 years old
(1) Suitable for opportunistic screening and population screening.
(2) Mammography once every 1 to 2 years.
(3) Combination with clinical physical examination is recommended.
(4) Combination with ultrasound is recommended for dense breasts.
4.4 70 years of age or older
(1) Suitable for opportunistic screening.
(2) Mammography once every 2 years.
(3) Combination with clinical physical examination is recommended.
(4) Combined with ultrasound examination is recommended for dense breast.
5.Screening for high-risk groups of breast cancer
It is recommended that screening should be done in advance (before the age of 40) for people with high risk of breast cancer, and the screening interval is recommended to be once every six months.
6. Definition of high-risk group for breast cancer
(1) Those with obvious genetic predisposition to breast cancer (see Appendix I for details).
(2) Patients with previous moderate to severe atypical hyperplasia or lobular carcinoma in situ in the ducts or lobules of the breast.
(3) Patients with previous history of chest radiotherapy.
Appendix I: Genetic testing criteria for hereditary breast cancer-ovarian cancer syndrome in hereditary high-risk groupsa, b
(1) Carriers of BRCA1/BRCA2 gene mutation in blood relatives.
(2) Patients with breast cancer who meet 1 or more of the following conditionsc.
(i) age at onset ≤ 45 years; (ii) age at onset ≤ 50 years and 1 consanguineous relatived who is also a breast cancer patient with age at onset ≤ 50 years and/or 1 or more consanguineous relatives who are ovarian epithelial/fallopian tube/primary peritoneal cancer patients of any age; (iii) a single individual with 2 primary breast cancerse and age at first onset ≤ 50 years; (iv) any age at onset and 2 or (4) Any age of onset of breast cancer and/or ovarian epithelial cancer, fallopian tube cancer, or primary peritoneal cancer in 2 or more consanguineous close relatives of any age of onset; (5) Breast cancer in a consanguineous male close relative; (6) Combined past history of ovarian epithelial cancer, fallopian tube cancer, or primary peritoneal cancer.
(3) Patients with ovarian epithelial carcinoma, fallopian tube carcinoma, or primary peritoneal carcinoma.
(4) Patients with male breast cancer.
(5) Family history of the following.
(i) Any of the above conditions in first or second degree relatives with consanguinity; (ii) Two or more patients with breast cancer (at least one with age of onset ≤ 50 years) and/or ovarian epithelial cancer/fallopian tube cancer/primary peritoneal cancer in third degree relatives with consanguinity.
Notes.
a. Meeting 1 or more of the conditions suggests a possible hereditary breast cancer-ovarian cancer syndrome, necessitating specialized evaluation. When reviewing the patient’s family history, paternal and maternal relatives with cancer should be considered separately. Early-onset breast cancer and/or ovarian epithelial, fallopian tube, and primary peritoneal cancer at any age suggest the possibility of hereditary breast-ovarian cancer syndrome, which in some families with hereditary breast-ovarian cancer syndrome also includes prostate cancer, pancreatic cancer, gastric cancer, and melanoma.
b. Other considerations: individuals with a limited family history, such as <2 female first- or second-degree relatives, or female relatives >45 years of age, in which case the likelihood of carrying the mutation is often underestimated. Patients with triple-negative breast cancer with an age of onset ≤40 years should be considered for testing for BRCA1/2 gene mutations.
c. Breast cancer includes invasive and intraductal cancers.
d. Close relatives are defined as first-, second- and third-degree relatives.
e. 2 primary breast cancers include bilateral breast cancers or 2 or more definite primary breast cancers of different origin in the same side of the breast.