Breast cancer can sometimes be detected in its early stages using a mammogram, an X-ray of the breast. Mammography is most beneficial for women as they age and undergo menopause. Mammography is a screening tool that can detect the possible presence of an abnormal tissue mass. By itself, it is not accurate enough to provide definitive proof of either the presence or the absence of breast cancer. If a mammogram indicates the presence of an abnormality, further tests must be done to determine whether breast cancer actually is present.