breast cancer screening breast cancer screening breast cancer screening is the medical screening of asymptomatic, apparently healthy women for breast cancer in an attempt to achieve an earlier diagnosis. the assumption is that early detection will improve outcomes. a number of screening tests have been employed, including clinical and self breast exams, mammography, genetic screening, ultrasound, and magnetic resonance imaging. breast cancer screeninga woman having a mammogram a clinical or self breast exam involves feeling the breast for lumps or other abnormalities. medical evidence, however, does not support its use in women with a typical risk for breast cancer. universal screening with mammography is controversial as it may not reduce all-cause mortality and may cause harms through unnecessary treatments and medical procedures. many national organizations recommend it for most older women. the united states preventive services task force recommends screening mammography in women at normal risk for breast cancer, every two years between the ages of 50 and 74. other positions vary from no screening to starting at age 40 and screening yearly. several tools are available to help target breast cancer screening to older women with longer life expectancies. similar imaging studies can be performed with magnetic resonance imaging but evidence is lacking. earlier, more aggressive, and more frequent screening is recommended for women at particularly high risk of developing breast cancer, such as those with a confirmed brca mutation, those who have previously had breast cancer, and those with a strong family history of breast and ovarian cancer. abnormal findings on screening are further investigated by surgically removing a piece of the suspicious lumps (biopsy) to examine them under the microscope. ultrasound may be used to guide the biopsy needle during the procedure. magnetic resonance imaging is used to guide treatment, but is not an established screening method for healthy women. breast exam a pictorial example of breast self-examination in six steps. steps 1-3 involve visual inspection of the breasts with the arms in different positions. step 4 is palpation of the breast. step 5 is palpation of the nipple. step 6 is palpation of the breast while lying down. main article: breast self-examination breast examination (either clinical breast exams (cbe) by a health care provider or by self exams) were once widely recommended. they however are not supported by evidence and may, like mammography and other screening methods that produce false positive results, contribute to harm. the use of screening in women without symptoms and at low risk is thus controversial. a 2003 cochrane review found screening by breast self-examination is not associated with lower death rates among women who report performing breast self-examination and does, like other breast cancer screening methods, increase harms, in terms of increased numbers of benign lesions identified and an increased number of biopsies performed. they conclude "at present, breast self-examination cannot be recommended". there was no high quality evidence looking at clinical breast examination. mammography main article: mammography mammography is a common screening method, since it is relatively fast and widely available in developed countries. mammography is a type of radiography used on the breasts. it is typically used for two purposes: to aid in the diagnosis of a woman who is experiencing symptoms or has been called back for follow-up views (called diagnostic mammography), and for medical screening of apparently healthy women (called screening mammography). mammography is not very useful in finding breast tumors in dense breast tissue characteristic of women under 40 years. in women over 50 without dense breasts, breast cancers detected by screening mammography are usually smaller and less aggressive than those detected by patients or doctors as a breast lump. this is because the most aggressive breast cancers are found in dense breast tissue, which mammograms perform poorly on. the european commission's scientific advice mechanism recommends that mri scans are used in place of mammography for women with dense breast tissue. the presumption was that by detecting cancer in an earlier stage, women will be more likely to be cured by treatment. this assertion, however, has been challenged by recent reviews which have found the significance of these net benefits to be lacking for women at average risk of dying from breast cancer. mechanism normal (left) versus cancerous (right) mammography image. screening mammography is usually recommended to women who are most likely to develop breast cancer. in general, this includes women who have risk factors such as having a personal or family history of breast cancer or being older women, but not being frail elderly women, who are unlikely to benefit from treatment. women who agree to be screened have their breasts x-rayed on a specialized x-ray machine. this exposes the woman's breasts to a small amount of ionizing radiation, which has a very small, but non-zero, chance of causing cancer. the x-ray image, called a radiograph, is sent to a physician who specializes in interpreting these images, called a radiologist. the image may be on plain photographic film or digital mammography on a computer screen; despite the much higher cost of the digital systems, the two methods are generally considered equally effective. the equipment may use a computer-aided diagnosis (cad) system. there is considerable variation in interpreting the images; the same image may be declared normal by one radiologist and suspicious by another. it can be helpful to compare the images to any previously taken images, as changes over time may be significant. if suspicious signs are identified in the image, then the woman is usually recalled for a second mammogram, sometimes after waiting six months to see whether the spot is growing, or a biopsy of the breast. most of these will prove to be false positives, resulting in sometimes debilitating anxiety over nothing. most women recalled will undergo additional imaging only, without any further intervention. recall rates are higher in the u.s. than in the uk. effectiveness on balance, screening mammography in older women increases medical treatment and saves a small number of lives. usually, it has no effect on the outcome of any breast cancer that it detects. screening targeted towards women with above-average risk produces more benefit than screening of women at average or low risk for breast cancer. a 2013 cochrane review estimated that mammography in women between 50 and 75 years old results in a relative decreased risk of death from breast cancer of 15% and an absolute risk reduction of 0.05%. however, when the analysis included only the least biased trials, women who had regular screening mammograms were just as likely to die from all causes, and just as likely to die specifically from breast cancer, as women who did not. the size of effect might be less in real life compared with the results in randomized controlled trials due to factors such as increased self-selection rate among women concerned and increased effectiveness of adjuvant therapies. the nordic cochrane collection (2012) reviews said that advances in diagnosis and treatment might make mammography screening less effective at saving lives today. they concluded that screening is "no longer effective" at preventing deaths and "it therefore no longer seems reasonable to attend" for breast cancer screening at any age, and warn of misleading information on the internet. the review also concluded that "half or more" of cancers detected with mammography would have disappeared spontaneously without treatment. they found that most of the earliest cell changes found by mammography screening (carcinoma in situ) should be left alone because these changes would not have progressed into invasive cancer. the accidental harm from screening mammography has been underestimated. women who have mammograms end up with increased surgeries, chemotherapy, radiotherapy and other potentially procedures resulting from the over-detection of harmless lumps. many women will experience important psychological distress for many months because of false positive findings. half of suspicious findings will not become dangerous or will disappear over time. consequently, the value of routine mammography in women at low or average risk is controversial. with unnecessary treatment of ten women for every one woman whose life was prolonged, the authors concluded that routine mammography may do more harm than good. if 1,000 women in their 50s are screened every year for ten years, the following outcomes are considered typical in the developed world: one woman's life will be extended due to earlier detection of breast cancer. 2 to 10 women will be overdiagnosed and needlessly treated for cancer that would have stopped growing on its own or otherwise caused no harm during the woman's lifetime. 5 to 15 women will be treated for breast cancer, with the same outcome as if cancer had been detected after symptoms appeared. 500 will be incorrectly told they might have breast cancer (false positive). 125 to 250 will undergo breast biopsy. the outcomes are worse for women in their 20s, 30s, and 40s, as they are far less likely to have a life-threatening breast cancer, and more likely to have dense breasts that make interpreting the mammogram more difficult. among women in their 60s, who have a somewhat higher rate of breast cancer, the proportion of positive outcomes to harms are better: for women in their 40s: about 2,000 women would need to be screened every year for 10 years to prevent one death from breast cancer. 1,000 of these women would experience false positives, and 250 healthy women would undergo unnecessary biopsies. for women in their 50s: about 1,350 women would need to be screened for every year for 10 years to prevent one death from breast cancer. half of these women would experience false positives, and one-quarter would undergo unnecessary biopsies. for women in their 60s: about 375 women would need to be screened for every year for 10 years to prevent one death from breast cancer. half of these women would experience false positives, and one-quarter would undergo unnecessary biopsies. mammography is not generally considered as an effective screening technique for women at average or low risk of developing cancer who are less than 50 years old. for normal-risk women 40 to 49 years of age, the risks of mammography outweigh the benefits, and the us preventive services task force says that the evidence in favor of routine screening of women under the age of 50 is "weak". part of the difficulty in interpreting mammograms in younger women stems from breast density. radiographically, a dense breast has a preponderance of glandular tissue, and younger age or estrogen hormone replacement therapy contribute to mammographic breast density. after menopause, the breast glandular tissue gradually is replaced by fatty tissue, making mammographic interpretation much more accurate. recommendations recommendations to attend to mammography screening vary across countries and organizations, with the most common difference being the age at which screening should begin, and how frequently or if it should be performed, among women at typical risk for developing breast cancer. in england, all women were invited for screening once every three years beginning at age 50,. there is a trial in progress to assess the risks and benefits of offering screening to women aged 47 to 49. some other organizations recommend mammograms begin as early as age 40 in normal-risk women, and take place more frequently, up to once each year. women at higher risk may benefit from earlier or more frequent screening. women with one or more first-degree relatives (mother, sister, daughter) with premenopausal breast cancer often begin screening at an earlier age, perhaps at an age 10 years younger than the age when the relative was diagnosed with breast cancer. as of 2009 the united states preventive services task force recommends that women over the age of 50 receive mammography once every two years. in march 2022, the european commission's scientific advice mechanism recommended extending screening to women in their mid-40s. the cochrane collaboration (2013) states that the best quality evidence neither demonstrates a reduction in either cancer specific, nor a reduction in all-cause mortality from screening mammography. when less rigorous trials are added to the analysis there is a reduction in breast cancer specific mortality of 0.05% (a relative decrease of 15%). screening results in a 30% increase in rates of over-diagnosis and over-treatment, resulting in the view that it is not clear whether mammography screening does more good or harm. on their web site, cochrane currently concludes that, due to recent improvements in breast