The age and frequency of screening is controversial. Some cancer societies recommend screening at age 40, whereas others recommend screening starting at age 50 in normal-risk patients. Similarly, the ideal interval is controversial, with some recommending annual screenings and others biennially. At what age screening should stop is also unclear. Some agencies recommend that screening end at age 74 (US Preventive Services Task Force). Others recommend “continuing for as long as a woman is in good health” (American Cancer Society). In addition to mammography, the American Cancer Society recommends clinical breast examination every 3 years from age 20–39 and annually thereafter. The US Preventive Services Task Force sites insufficient evidence to recommend clinical breast examination.

Mammograms utilize small doses of radiation, which over time, can place patients at an increased risk for cancer. However, for most women over 50, the benefits of regular mammograms outweigh any potential radiation risks. Additionally, mammograms can miss up to 20 % of cancers if they are too small or in areas that are difficult to view. On the other end of the spectrum, it may detect cancers that would have otherwise never led to symptoms, subjecting the patient to the adverse effects of intervention or additional testing (e.g., biopsy). Lastly, mammograms are not always accurate. Mammographic findings are heavily dependent on the technique used in attaining the images, the experience of the radiologist evaluating the images, and the breast density of the patient.

Younger women tend to have denser breast tissue due to a decreased level of fat. Dense breasts make it difficult to detect abnormal calcifications or masses. Nevertheless, masses may still be detected with mammograms.

The most commonly implemented risk assessment model is the Breast Cancer Risk Assessment Tool (BCRAT), also known as the Gail model. The BCRAT is a mathematical model used to calculate the risk of developing breast cancer. The model considers factors such as age, age at menarche, reproductive history, family history in first-degree relatives, and prior biopsies. One disadvantage of the model is that it can underestimate breast cancer risk in women with a strong family history of breast or ovarian cancer that does not involve first-degree relatives; if this is the case, alternative risk models should be implemented.

Larger calcifications (macrocalcifications) are almost always benign, while smaller calcifications (microcalcifications) are more frequently seen in patients with breast cancer.

Ductal carcinoma in situ (DCIS) is characterized by malignant epithelial cells within the mammary ductal system, without invasion into the surrounding stroma (Table 4.1). DCIS has several histological patterns, including comedo with prominent central necrosis, cribriform with back to back glands, and papillary. Comedo-type DCIS is typically high grade and associated with a worse prognosis. DCIS is often multifocal and can be associated with a concurrent invasive carcinoma. DCIS lesions have a high risk of subsequent invasive carcinoma at the site of the DCIS.