Typically, there are two main stages of breast cancer examinations, screening and diagnostic. Screening tests look for signs of breast cancer in asymptomatic women in order to allow for early detection, and should be performed on a routinely basis every 1 to 2 years (or less, in certain cases) depending on woman's age and risk profile. Diagnostic tests are mandated when breast cancer is suspected or has been diagnosed, requiring a more thorough investigation.
Breast Self Exam (BSE) is the most simple and readily available screening method. Ideally, it will be performed by all women on a regular monthly basis, allowing the woman a better chance of early detecting suspicious lumps as well as better familiarity with her breasts' regular structure. It is a quick and free exam, not requiring any help.
Nevertheless, BSE should not be relied upon solely, for several reasons: first, when a tumor is large enough to be palpated, it has usually reached a relatively advanced stage. Secondly, there are normal breast tissue changes that occur with age, menstrual cycle, pregnancy and menopause or from taking birth control pills, which may cause many "false alarms", unnecessary anxiety and redundant doctor visits. These disadvantages become substantially less significant the more frequent BSE are exercised and in adjunct to other screening methods.
A Clinical Breast Exam (CBE) is performed by a healthcare provider - physician, nurse or any other qualified professional. The healthcare provider inspects both breasts for shape, size, and color and palpates them to feel lumps or other problems. The advantages of CBE are its low cost, its availability, and the fact that an experienced professional performs it. The great disadvantage, however, is once again the stage the tumor reaches before it becomes palpable.
X-ray mammography is a method of acquiring an x-ray image of the breast in order to detect masses and microcalcifications in the breast tissue. Like all x-ray exams, mammography uses ionizing radiation to create images, although milder than the radiation used for hard tissue imaging. During the mammography procedure, the breast is compressed between two plates in order to flatten it as much as possible - exposing more of the breast to the camera and reducing the amount of radiation required to form a clear image. X-ray mammography is used both as a screening exam and as a diagnostic exam.
Along with its many virtues, mammography has quite a few drawbacks among which are limited accuracy (it fails to correctly identify approx. 20% of tumors, and approx. 80% of biopsies that follow a positive mammogram turn out negative for breast cancer), extreme inconvenience, exposure to radiation, and it being unsuitable for women with denser breasts (which constitutes approx. 30% of all women aged 50 and more and nearly 100% of women under the age of 40).
The main limitation of both Screen Film Mammography (SFM) and Full Field Digital Mammography (FFDM) is the fact that the three dimensional anatomical information i.e. the breast is projected into a two dimension image plane. Therefore, anatomical structures that overlap the tumor limit the radiologist's ability to detect certain cancers. 3D Tomosynthesis claims to overcome this limitation by acquiring several views of the breast from different viewing angles and reconstructing slice images into a 3D volume set. Moreover, 3D Tomosynthesis causes the examinee less discomfort than mammography does, as it does not require the same level of compression of the breast as mammography. Nevertheless, Tomosynthesis bears one major drawback - the amount of radiation it exposes the examinee to, is at least twice as much as conventional mammography requires. 3D Tomography devices are currently not approved for marketing.
A breast ultrasound (BUS) examination is an investigative technology used for diagnosis rather than a screening test. It is performed when a suspicious finding is spotted during mammography or a CBE. BUS allows the physician to more thoroughly examine suspicious masses in the breasts with significant freedom in obtaining images of the breast from almost any orientation.
Ultrasound uses high-frequency sound waves that are transmitted through breast tissue and bounce differently off dissimilar tissue types. Because ultrasound is excellent at imaging cysts - round, fluid-filled pockets - inside the breast, it often quickly determines if a suspicious mass is in fact a cyst or a solid tissue. Solid mass diagnosis by BUS may require a biopsy to determine whether it is malignant.
Breast Magnetic Resonance Imaging (MRI) is a powerful diagnostic tool that uses a magnetic field and RF transmission to create images of the body. During a breast MRI exam, the examinee lies facing down and is moved in and out of a narrow tube as the machine creates images of her body.
The value of MRI for breast cancer detection has not been unequivocally proven yet, although some physicians and radiologists believe MRI can distinguish a breast cancer from normal breast gland tissue better than other imaging techniques. Moreover, MRI is effective in assessing lesions even in densely glandular breasts, making it applicable for the diagnosis of breast cancer in women younger than 40. However, due to the exam's significant high cost and the limited number of MRI centers and adequately trained experts, it is unlikely to be used as a general screening tool. In addition, breast MRI suffers from a high false positive rate of 20%. Still, it may be proven useful in evaluating women who have a palpable mass that is not visible with ultrasound or mammography and for screening of young women at high risk of cancer (family history or breast cancer related genes).
Infrared (IR) breast imaging, unlike other imaging modalities, is a passive imaging technique that does not expose the patient to any kind of radiation. Rather, it measures the thermal radiation naturally emitted from the breast tissue using an Infra Red measurement device ("infrared camera").
The principle underlying Infrared Breast Imaging is that dissimilar tissue emit different levels of heat, in part due to increased vascularization (which, in the case of tumors, is already present while the tumor is as small as 2 cubic mm) and in part due to increased metabolic activity - such that is particularly present when a tissue is exhibiting an enhanced growth. The greater blood flow to tumor site and enhanced metabolic activity can be detected in the infrared image as differences in light absorption signal.
Infrared imaging devices were developed as early as 3 decades ago. However, due to the old fashioned technology used by the early IR imaging devices and an insufficient understanding of bio-thermodynamics, IR imaging showed less than dissatisfying results and was unable to prove neither superiority nor equivalency to other imaging modalities.