Breast cancer is the second most-common cancer in the United States, following skin cancer, according to the Mayo Clinic. Screening is for early detection of breast cancer, allowing diagnosis before symptoms manifest, at which point the cancer is typically large and spread beyond the breast tissue. Finding breast cancer while it's small and contained to the breast are the most important factors for a promising prognosis, as the American Cancer Society (ACS) explains.
Clinical Breast Exam
The most basic method of breast cancer screening is a clinical breast exam. It is a manual examination of the breasts performed by a doctor or other health care professional. Breasts and underarms are thoroughly felt for lumps or other anomalies. The ACS recommends women in their 20s and 30s get a clinical breast exam at least once every three years, and that women in their 40s and older undergo the exam annually.
Women should perform their own breast exams at home, too. The ACS suggests starting breast self-exams in your 20s. Familiarize yourself with the way your breasts look and feel. See your doctor as soon as possible if you notice any changes.
Mammogram
Mammograms are X-rays of the breasts. They are useful for their ability to find tumors too small to feel with a clinical breast exam. Additionally, as the National Cancer Institute (NCI) points out, they detect ductal carcinoma in situ, a cellular abnormality that is sometimes a precursor to breast cancer.
The NCI explains that mammograms have some shortcomings, with findings depending on the size of a tumor, breast tissue density and even the experience level of the performing radiologist. Tumors are difficult to spot on a mammogram. Mammograms are most successfully used in women over 50, according to the NCI.
The ACS recommends women over 40 get a mammogram once every year.
Ultrasound
Ultrasounds are not a first method of breast cancer screening, but are a follow-up test if a clinical breast exam or mammogram finds anything suspicious, states the NCI. This technology bounces sound waves off the internal parts of the body, using echo patterns to construct images of masses in the body.
MRI
MRI (magnetic resonance imaging) is in use for breast cancer screening, but its efficacy is still being studied in clinical trials. Similar in principle to an ultrasound, and MRI uses sound and radio waves to build pictures of internal structures. MRIs can pick up more than mammograms, according to the NCI. The increased sensitivity means finding tumors and abnormalities a mammogram misses, but on the other hand, it also means finding more benign abnormalities. At this point, MRIs are relied on more for diagnosis than for screening.
Tissue Biopsy
Biopsy entails removing a sample of breast tissue for laboratory examination. Like MRIs, this method is used more for diagnosis than for screening. However, clinical studies are underway to determine how best to use tissue sampling in the screening process, according to the NCI.
