What is screening?
Screening is looking for signs of disease, such as breast cancer, before a person has symptoms. The goal of screening tests is to find cancer at an early stage when it can be treated and may be cured. Sometimes a screening test finds cancer that is very small or very slow growing. These cancers are unlikely to cause death or illness during the person's lifetime. Scientists are trying to better understand which people are more likely to get certain types of cancer. For example, they look at the person's age, their family history, and certain exposures during their lifetime. This information helps doctors recommend who should be screened for cancer, which screening tests should be used, and how often the tests should be done. It is important to remember that your doctor does not necessarily think you have cancer if he or she suggests a screening test. Screening tests are done when you have no cancer symptoms. Women who have a strong family history or a personal history of cancer or other risk factors may also be offered genetic testing. If a screening test result is abnormal, you may need to have more tests done to find out if you have cancer. These are called diagnostic tests, rather than screening tests.
Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.
Breast cancer is the second leading cause of death from cancer in American women. Different factors increase or decrease the risk of breast cancer. Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast. The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called lobes, which have many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can produce milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts. Each breast also has blood vessels and lymph vessels. The lymph vessels carry an almost colorless, watery fluid called lymph. Lymph vessels carry lymph between lymph nodes. Lymph nodes are small, bean-shaped structures that filter lymph and store white blood cells that help fight infection and disease. Groups of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.
Breast cancer is the leading cause of death from cancer in Indian women. Women in the India get breast cancer more than any other type of cancer. Breast cancer is more likely to occur as a woman ages. Breast cancer rarely occurs in men. Because men with breast cancer usually have a lump that can be felt, screening tests are not likely to be helpful. Different factors increase or decrease the risk of breast cancer.
Breast Cancer Screening
KEY POINTS
Tests are used to screen for different types of cancer when a person does not have symptoms. Mammography is the most common screening test for breast cancer. Magnetic resonance imaging (MRI) may be used to screen women who have a high risk of breast cancer. Whether a woman should be screened for breast cancer and the screening test to use depends on certain factors. Other screening tests have been or are being studied in clinical trials. Breast Exam Thermography Tissue sampling -- Tests are used to screen for different types of cancer when a person does not have symptoms. Scientists study screening tests to find those with the fewest harms and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) helps a person live longer or decreases a person’s chance of dying from the disease. For some types of cancer, the chance of recovery is better if the disease is found and treated at an early stage.
Mammography is the most common screening test for breast cancer. A mammogram is a picture of the inside of the breast. Mammography may find tumors that are too small to feel. It may also find ductal carcinoma in situ (DCIS). In DCIS, abnormal cells line the breast duct, and in some women may become invasive cancer. There are three types of mammograms: Film mammography is an x-ray picture of the breast. Digital mammography is a computer picture of the breast. Digital breast tomosynthesis (DBT) uses x-rays to take a series of pictures of the breast from many different angles. A computer is used to make 3-D pictures of the breast from these x-rays.
Many factors affect whether mammography is able to detect (find) breast cancer:
- The age and weight of the patient.
- The size and type of tumor.
- Where the tumor has formed in the breast.
- How sensitive the breast tissue is to hormones.
- How dense the breast tissue is.
- The timing of the mammography within the woman's menstrual cycle.
- The quality of the mammogram picture.
- The skill of the radiologist in reading the mammogram.
Women aged 50 to 69 years who have screening mammograms have a lower chance of dying from breast cancer than women who do not have screening mammograms.
Magnetic resonance imaging (MRI) may be used to screen women who have a high risk of breast cancer. MRI is a procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI). MRI does not use any x-rays and the woman is not exposed to radiation. MRI may be used as a screening test for women who have a high risk of breast cancer. Factors that put women at high risk include the following:
- Certain gene changes, such as changes in the BRCA1 or BRCA2 genes.
- A family history (first degree relative, such as a mother, daughter or sister) with breast cancer.
- Certain genetic syndromes, such as Li-Fraumeni or Cowden syndrome.
- An MRI is more likely than mammography to find a breast mass that is not cancer.
Women with dense breasts who have supplemental screening (for example, an MRI) show higher rates of breast cancer detection, but there is limited evidence about whether this leads to better health outcomes.
Whether a woman should be screened for breast cancer and the screening test to use depends on certain factors. Women with risk factors for breast cancer, such as certain changes in the BRCA1 or BRCA2 gene or certain genetic syndromes may be screened at a younger age and more often. Women who have had radiation treatment to the chest, especially at a young age, may start routine breast cancer screening at an earlier age.
The benefits and risks of mammograms and MRIs for these women have not been studied.
Breast cancer screening has not been shown to benefit the following women:
- Elderly women who, if diagnosed with breast cancer through screening, will usually die of other causes.
- Screening mammograms for those aged 66 to 79 years may find cancer in a very small percentage of women, but most of these cancers are low risk.
- In women with an average risk of developing breast cancer, screening mammography before age 40 has not shown any benefit.
- In women who are not expected to live for a long time and have other diseases or conditions, finding and treating early stage breast cancer may reduce their quality of life without helping them live longer.
Other screening tests have been or are being studied in clinical trials.
Studies have been done to find out if the following breast cancer screening tests are useful in finding breast cancer or helping women with breast cancer live longer.
Breast Exam A clinical breast exam is an exam of the breast by a doctor or other health professional. He or she will carefully feel the breasts and under the arms for lumps or anything else that seems unusual. It is not known if having clinical breast exams decreases the chance of dying from breast cancer. Breast self-exams may be done by women or men to check their breasts for lumps or other changes. If you feel any lumps or notice any other changes in your breasts, talk to your doctor. Doing regular breast self-exams has not been shown to decrease the chance of dying from breast cancer.
Thermography Thermography is a procedure in which a special camera that senses heat is used to record the temperature of the skin that covers the breasts. Tumors can cause temperature changes that may show up on the thermogram. There have been no randomized clinical trials of thermography to find out how well it detects breast cancer or the harms of the procedure.
Tissue sampling Breast tissue sampling is taking cells from breast tissue to check under a microscope. Breast tissue sampling as a screening test has not been shown to decrease the risk of dying from breast cancer. Screening tests for breast cancer are being studied in clinical trials.
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Dr Pratik Patil
Medical Oncologist, Pune.
9637439163