 [ Symptoms ] would lad lesion cause tachycardia [ Disease ] mammography is an x ray examination of the breast that has the ability to detect a cancer in the breast when it is quite small long before it may be felt by breast examination approximately 85 90 of all breast cancers are detectable by mammography early detection by mammography has reduced the mortality rate from breast cancer by 20 30 in women over 50 years of age however some 10 15 of breast cancers are not visible on mammography but can be felt on physical examination of the breast therefore a normal mammogram does not exclude the possibility of breast cancer breast examination by your health care professional by palpation and visual inspection is also important during a routine physical checkup a doctor can conduct an examination of the breast