Breast neoplasms consist of a wide spectrum of pathologies from benign proliferations, high-risk lesions, precursor lesions, to invasive malignancies. This article provides an overview for radiologists, with a focus on breast cancer.
For a summary article for medical students and non-radiologists, see breast cancer (summary).
On this page:
Epidemiology
Breast cancer is the most common nonskin malignancy in women. In the affluent populations of North America, Europe, and Australia, 6% of women develop invasive breast cancer before age 75, compared to a 2% risk in developing regions of Africa and Asia 8. The difference has been attributed to risks associated with a Westernized lifestyle, including high-calorie diet rich in fat and protein and physical inactivity 8.
Risk factors
increasing age 8
-
reproductive lifestyle factors increasing unopposed oestrogen load 8
early menarche
nulliparity, infertility, or, if parous, few children with late age at first delivery
lack of breastfeeding
late menopause
unopposed oestrogen hormone replacement therapy
personal history of breast cancer or a high risk breast lesion
first degree relative with breast cancer
-
genetic mutations
alcohol consumption 8
Pathology
Classification
The main pathological classification of breast neoplasms is published by the World Health Organisation: WHO classification of tumours of the breast.
The vast majority of breast cancers are adenocarcinomas (99%). The most common types are 8:
invasive carcinoma of no special type (ductal carcinoma not otherwise specified): 40-75%
ductal carcinoma in situ: 20-25%
invasive lobular carcinoma: 5-15%
Categories of benign epithelial neoplasms include:
Non-epithelial malignancies are uncommon and include:
breast sarcomas (0.5-3% 6)
Immunophenotype
Three molecular biomarkers are routinely evaluated in invasive breast cancers because they have therapeutic implications:
oestrogen receptor (ER)
progesterone receptor (PR)
human epidermal growth factor receptor 2 (HER2; proto-oncogene Neu; receptor tyrosine-protein kinase erbB-2)
Staging
Staging of breast tumours is performed according to the TNM system published by the American Joint Committee on Cancer (AJCC) / Union for International Cancer Control (UICC): breast cancer (staging).
Radiographic appearance
Dedicated evaluation of the breast involves multiple imaging modalities to detect and localise lesions for biopsy. In all modalities, regional metastasis can be suspected by the presence of axillary adenopathy.
Mammography
Neoplasms have varied appearances, including masses, asymmetries, calcifications, or architectural distortions.
Ultrasound
Neoplasms can appear as masses or architectural distortions. Calcifications can sometimes be seen.
MRI
Neoplasms can manifest as masses with or without enhancement, non-mass enhancement, or foci of enhancement.
CT
Breast masses may be incidentally identified but CT is not the preferred modality for dedicated breast evaluation. If calcifications are visualised on CT, they are nearly all benign 9.
Radiology report
The use of a standard lexicon is recommended to enhance communication with referrers and audit performance: breast imaging-reporting and data system (BI-RADS).
Unable to process the form. Check for errors and try again.