This is a medical question of type : exams and tests 
 How to diagnose Breast Cancer ? 
 Most cancers in their early, most treatable stages do not cause any symptoms. That is why it's important to have regular tests to check for cancer long before you might notice anything wrong. Detecting Breast Cancer Through Screening When breast cancer is found early, it is more likely to be treated successfully. Checking for cancer in a person who does not have any symptoms is called screening. Screening tests for breast cancer include, among others, clinical breast exams and mammograms. Recent studies have shown that ultrasound and MRI's may also be useful complementary screening tools, particularly in women with mammograms that are not definitive. During a clinical breast exam, the doctor or other health care professional checks the breasts and underarms for lumps or other changes that could be a sign of breast cancer.  A mammogram is a special x-ray of the breast that often can detect cancers that are too small for a woman or her doctor to feel. (Watch the video to learn more about digital mammography and dense breasts. To enlarge the video, click the brackets in the lower right-hand corner. To reduce the video, press the Escape (Esc) button on your keyboard.) Who Should Have a Mammography? Several studies show that mammography screening has reduced the number of deaths from breast cancer. However, some other studies have not shown a clear benefit from mammography. Scientists are continuing to examine the level of benefit that mammography can produce. The U.S. Preventive Services Task Force (USPSTF) recommends a screening mammography for women 50-74 years every two years.  Learn more about the USPSTF mammography recommendations here. Between 5 and 10 percent of mammogram results are abnormal and require more testing. Most of these follow-up tests confirm that no cancer was present. Worried about the cost of a mammogram? Learn about free and low-cost screenings. (Centers for Disease Control and Prevention) How Biopsies are Performed If needed, the most common follow-up test a doctor will recommend is called a biopsy. This is a procedure where a small amount of fluid or tissue is removed from the breast to make a diagnosis. A doctor might perform fine needle aspiration, a needle or core biopsy, or a surgical biopsy. - With fine needle aspiration, doctors numb the area and use a thin needle to remove fluid and/or cells from a breast lump. If the fluid is clear, it may not need to be checked out by a lab.  - For a needle biopsy, sometimes called a core biopsy, doctors use a needle to remove tissue from an area that looks suspicious on a mammogram but cannot be felt. This tissue goes to a lab where a pathologist examines it to see if any of the cells are cancerous.  - In a surgical biopsy, a surgeon removes a sample of a lump or suspicious area. Sometimes it is necessary to remove the entire lump or suspicious area, plus an area of healthy tissue around the edges. The tissue then goes to a lab where a pathologist examines it under a microscope to check for cancer cells.  With fine needle aspiration, doctors numb the area and use a thin needle to remove fluid and/or cells from a breast lump. If the fluid is clear, it may not need to be checked out by a lab. For a needle biopsy, sometimes called a core biopsy, doctors use a needle to remove tissue from an area that looks suspicious on a mammogram but cannot be felt. This tissue goes to a lab where a pathologist examines it to see if any of the cells are cancerous. In a surgical biopsy, a surgeon removes a sample of a lump or suspicious area. Sometimes it is necessary to remove the entire lump or suspicious area, plus an area of healthy tissue around the edges. The tissue then goes to a lab where a pathologist examines it under a microscope to check for cancer cells. Another type of surgical biopsy that removes less breast tissue is called an image-guided needle breast biopsy, or stereotactic biopsy. Eighty percent of U.S. women who have a surgical breast biopsy do not have cancer. However, women who have breast biopsies are at higher risk of developing breast cancer than women who have never had a breast biopsy. Other Detection Methods Magnetic resonance imaging, or MRI, and ultrasound are two other techniques which, as supplements to standard mammography, might help detect breast cancer with greater accuracy. Genetic Detection The most comprehensive study to date of gene mutations in breast cancer, published in September 2012, confirmed that there are four primary subtypes of breast cancer, each with its own biology. The four groups are called intrinsic subtypes of breast cancer and include HER2-enriched (HER2E), Luminal A (LumA), Luminal B (LumB) and Basal-like. The outlook for survival is different for each of these subtypes of breast cancer. Researchers found that one subtype, Basal-like breast cancer, shares many genetic features with a form of ovarian cancer, and that both may respond similarly to drugs that reduce tumor growth or target DNA repair. The authors hope that discovery of these mutations will be an important step in the effort to improve therapies for breast cancer. For the time being, there are no genetic tests that are commercially available based solely on these findings. Soon, however, knowing extensively which breast cancer gene mutations a woman has should help guide precision treatment.