Has Your Old Cancer Returned or Is It New?

By Lillie Shockney, R.N., M.A.S. - Posted on Fri, Mar 16, 2007, 12:00 pm PDT

Women who've had breast cancer sometimes say their "breast cancer has come back in the breast." What they mean is that they have a local recurrence of their disease. But there are situations in which the second discovery of cancer isn't a recurrence of the previous breast cancer but a brand new tumor that's grown in the same breast.

Here are several signs that help your doctor figure out whether a new finding of cancer is a recurrence or a new disease:

 Most local recurrences from the original cancer happen in the tumor bed where the original cancer grew. That means it's in the same quadrant of the breast. Most local recurrences happen within a couple of years after completion of the original cancer treatment. If it's been a long time (say, 15 years) since you first had cancer when a "new" cancer is found in the breast, there's a good chance that it literally is a new cancer unrelated to the earlier cancer.

 Comparing the pathology and prognostic factors of both tumors helps, too. If the doctor sees that the new cancer has a different pathology - for example, it's a different type of breast cancer, it has different ER receptors, its Her2neu status (positive or negative) is different - this is another sign that the cancer is new and not related to the original disease.
Many cancer experts now wonder if some recurrences aren't really cancers that were there all along but were not detected earlier. If so, this means there was more than one cancer in the breast at the same time. This is especially likely in cases of "recurrence" within months of completing treatment.
To resolve this doubt in women with a high risk of recurrence, doctors may order more breast MRIs before treatment is begun for women with dense breast tissue to detect even more possible lesions that aren't easily found by mammography or ultrasound.