Defining the Boundaries of the Breast

When we think about "the breasts" and visualize their anatomy, we usually think about the mound of the breast, the nipple, and the areola. It might surprise you to know, then, that the tissues of the breast encompass a much larger area that this, extending as they do all the way up to your collar bone and all the way down to about 1 or 2 inches below the elastic band of your bra. Oh, and the breast tissues also extend sideways all the way to underneath your armpit area.

In fact, when we think about where breast cancers are most commonly found within the breast, 70 percent of them grow in the region of the breast mound closest to the armpits (the "upper-outer quadrant" of the breast).

Examining the outlying areas

This is why knowing about these boundaries is so important. When you're doing a breast self exam, you do not want to be focusing just on the mound area. Let your fingers do some more walking and check out the other anatomic zones I've just mentioned. That way, you can be sure that nothing unusual is happening in any of the more out-of-the-way regions where breast tissue resides.

Self exams after mastectomy?

That's right--you'll still need to do a breast self exam each month even if you've had mastectomy surgery. Though the skin of the breast is a different organ and so is not technically breast tissue, it's virtually impossible to surgically remove every single breast cell. And since microscopic breast cells can still remain underneath this skin, we tell patients that, even with a mastectomy, they still will have a 1-percent to 3-percent risk of getting local recurrence where the cancer once began.

So, when doing your breast self exam each month, please don't leave anything out--remember to check the outlying border areas beyond the breast mound.


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