Lumpectomy Margins

The minimum amount of breast cancer that can be detected depends on what type of cancer you are dealing with. In terms of a lump or mass (usually representing an invasive ductal cancer), a tumor as small as 3-4 millimeters (25 millimeters = one inch, so 3-4 millimeters is well under 1/4 of an inch) can sometimes be seen on mammogram, ultrasound or MRI, depending on the density of the breast tissue. DCIS, or in-situ (or noninvasive) cancer often does not form a mass, and typically is detected when microcalcifications are seen on mammogram - again the amount of disease can range from just a few millimeters to a much larger area. Unfortunately both non-invasive and invasive cancers can be present without microcalcifications or a mass on imaging, so sometimes it is very difficult to get a true idea of the extent of disease before surgery. Once the tissue is removed, the pathologist will measure the size of the cancer - it may be larger or smaller than what was anticipated based on the imaging studies.

As far as the minimum amount of breast tissue removed at lumpectomy - it really varies tremendously - there is no standard. The goal of a lumpectomy is to remove the tumor and a "margin" - a rim of normal breast tissue - and still preserve as best possible the cosmetic appearance of the breast. There remains considerable debate on what an adequate margin is - some will be comfortable with no cancer cells right at the edge of the specimen, and some like to go for a wide margin, as large as one centimeter (10 millimeters) or greater. As in many areas, the truth is probably somewhere in between - usually 2-5 millimeters is generally acceptable for invasive cancer and 5 millimeters or greater for DCIS. But as I mentioned in the paragraph above, it can sometimes be difficult to estimate the true extent of the cancer, which makes it very difficult to give a good estimate prior to surgery of just how much tissue will be removed. In addition, at the time of surgery sometimes areas of adjacent tissue look or feel abnormal - it's sometimes a judgement call how much to remove. We try to balance between not having to return to the operating room due to positive margins, versus the poor cosmetic results of removing too much normal breast tissue.

There are some devices being evaluated that are looking at intraoperative margin assessment - being able to tell during the surgery if breast tissue at the edge of the tumor has cancer cells or not. These devices are under investigation, but do seem promising for providing the surgeon more information during the procedure regarding how much tissue to remove. The minimum amount of breast cancer that can be detected depends on what type of cancer you are dealing with. In terms of a lump or mass (usually representing an invasive ductal cancer), a tumor as small as 3-4 millimeters (25 millimeters = one inch, so 3-4 millimeters is well under 1/4 of an inch) can sometimes be seen on mammogram, ultrasound or MRI, depending on the density of the breast tissue. DCIS, or in-situ (or noninvasive) cancer often does not form a mass, and typically is detected when microcalcifications are seen on mammogram - again the amount of disease can range from just a few millimeters to a much larger area. Unfortunately both non-invasive and invasive cancers can be present without microcalcifications or a mass on imaging, so sometimes it is very difficult to get a true idea of the extent of disease before surgery. Once the tissue is removed, the pathologist will measure the size of the cancer - it may be larger or smaller than what was anticipated based on the imaging studies.

As far as the minimum amount of breast tissue removed at lumpectomy - it really varies tremendously - there is no standard. The goal of a lumpectomy is to remove the tumor and a "margin" - a rim of normal breast tissue - and still preserve as best possible the cosmetic appearance of the breast. There remains considerable debate on what an adequate margin is - some will be comfortable with no cancer cells right at the edge of the specimen, and some like to go for a wide margin, as large as one centimeter (10 millimeters) or greater. As in many areas, the truth is probably somewhere in between - usually 2-5 millimeters is generally acceptable for invasive cancer and 5 millimeters or greater for DCIS. But as I mentioned in the paragraph above, it can sometimes be difficult to estimate the true extent of the cancer, which makes it very difficult to give a good estimate prior to surgery of just how much tissue will be removed. In addition, at the time of surgery sometimes areas of adjacent tissue look or feel abnormal - it's sometimes a judgement call how much to remove. We try to balance between not having to return to the operating room due to positive margins, versus the poor cosmetic results of removing too much normal breast tissue.

There are some devices being evaluated that are looking at intraoperative margin assessment - being able to tell during the surgery if breast tissue at the edge of the tumor has cancer cells or not. These devices are under investigation, but do seem promising for providing the surgeon more information during the procedure regarding how much tissue to remove.