How good is mammography at detecting tumors?
Can mammograms miss tumors?
Mammograms are the primary modality used in this country to screen for breast cancer and constitute a significant advance in the early detection of the disease. In fact, it is the only modality of screening that has been definitively shown to decrease the mortality due to breast cancer in those patients who are screened. Mammography has the ability to detect breast cancer between 1.5 to 4 years before it is clinically evident (as a mass on breast exam or by causing symptoms). However, the test is not perfect. The false negative rate of screening mammography (the likelihood that a person with breast cancer will get a mammogram that is read by a radiologist as negative for cancer) has been reported to be between 10-30%. Up to 15% of cancers detected on clinical breast exam are not visible on screening mammography. This is why the diagnosis of breast cancer requires a multimodal approach: several techniques of screening must be combined to maximize diagnostic accuracy. The two primary modalities are clinical breast exam by a licensed physician on at least an annual basis and a screening mammogram on at least an annual basis. If any of these two modalities produce findings suspicious for a tumor, diagnostic mammography is performed (more in depth, focused mammography guided towards investigating an abnormal finding). If these modalities yield abnormal findings then several approaches are used. Further imaging can be obtained with either ultrasound or MRI. Finally, the gold standard for diagnosis of breast lesions are biopsy and excision and pathologic analysis. Using this multimodal approach it is difficult to place exact figures on accuracy of detection, but the consensus is that the large majority of malignant lesions can be detected in an early stage across the majority patients who undergo regular screening. This screening process all begins with annual examination with a licensed physician, such as a primary care physician or OBGYN. I urge you to make an appointment with such a trusted professional so that you can discuss in person what risk category you fall into for breast cancer and what type of screening algorithm would be most appropriate for you.
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