QUESTION: Are there any cases in which a doctor found a cancerous lump with palpation that was not detected by X-ray or sonogram?
ANSWER: Yes, it is possible for a palpable lump—a lump you can feel—to be a cancer, even it isn't visible on a mammogram or a sonogram (ultrasound is another word for the same test). In fact, about 25% of breast cancers are diagnosed by palpation—and these cancers tend to be diagnosed a little later than they should, because people are overly reassured by the "normal" mammogram or sonogram test reports. If you feel a lump in your breast, there's about an 80% chance that it's NOT cancer, and about a 20% chance that it IS cancer.
So even if the mammogram doesn't show anything, you need to have a lump evaluated further just to make sure it's OK. Ultrasound is usually the next step. But some doctors go right to removing cells or fluid, so that a piece of the lump can be examined under the microscope (biopsied). Your doctor will likely recommend a special biopsy procedure where multiple pieces of breast tissue are removed through a hollow or "fine" needle. But if your doctor is very concerned that the lump might be cancer, he or she may suggest that the whole lump be removed as the next step.
—Marisa Weiss, M.D.