Most Women with DCIS Do Not Require Sentinel Lymph Node Removal

P. Veronesi, et al., Primary Therapy of Early Breast Cancer Conference, St. Gallen, Switzerland, January 2005, Abstract # S17

Background and importance of the study: When you're diagnosed with breast cancer, your treatment and outlook depends, in part, on whether breast cancer cells are found in the lymph nodes near the affected breast. Lymph nodes trap breast cancer cells that break away from the original tumor and that get swept up into the lymph fluid that drains from the breast. Sometimes the cancer cells go no further than the lymph nodes. But the presence of cells in the lymph nodes can mean a higher risk of the cancer spreading to another part of the body.

Ductal carcinoma in situ (DCIS) is the most common kind of non-invasive breast cancer. This type of cancer (which some experts call a "pre-cancer") hasn't grown through the wall of the milk duct. As a result, it has a very low risk of spreading beyond the breast. DCIS is generally found on a mammogram. Cancer cells inside the ducts appear on the mammogram and may appear along with tiny specks or microcalcifications—the buildup of material left from old, dead cancer cells.

It's very uncommon for DCIS cells to spread to lymph nodes since the cells have not broken through the milk duct. But a very tiny portion of the cancer sometimes breaks part-way through the wall of the milk pipe. This is called microinvasion. You can't see microinvasion on a mammogram. It's found after surgery, when the tissue is examined by a pathologist using a microscope. Sometimes an area of microinvasion can be missed. This can happen when the area of invasion is very small and the piece of breast tissue is relatively much bigger.

There is usually no need to look at lymph nodes with a diagnosis of DCIS. But it may be important to evaluate lymph nodes in subtypes of DCIS that are more likely to go to lymph nodes. Why? Because treatment for DCIS that's spread to lymph nodes is very different from treatment for the usual kind of DCIS that doesn't spread.

One way to look for breast cancer in the lymph nodes is a procedure known as sentinel lymph node removal. During sentinel lymph node biopsy, a surgeon injects a blue dye, a radioactive substance (tracer), or both into the area around the cancer or behind the nipple. The dye or tracer works its way from the breast area to the lymph nodes.

The surgeon then removes this sentinel or "watchdog" lymph node, which is generally the one that first takes up the dye or tracer.

If a pathologist finds cancer cells in the sentinel lymph node, the surgeon may recommend taking out additional nodes near the sentinel node. But if no cancer cells are found in the sentinel node, no more nodes are removed. There are fewer side effects with sentinel lymph node removal compared to the standard lymph node procedure, because less tissue is altered or removed.

This study was done to see how often breast cancer cells were found in the sentinel lymph node in women diagnosed with DCIS.

Study design: Italian researchers performed sentinel lymph node removal on 482 women with DCIS that was diagnosed after a biopsy with no evidence of microinvasion. Most of the women had their sentinel lymph nodes removed at the same time they had a lumpectomy to remove the breast cancer. Pathologists then examined the tissue removed so that they could give a more definitive diagnosis of the type of breast cancer the women had.

Study results: The researchers found breast cancer cells in the sentinel lymph nodes of nine out of the 482 patients (1.9%). Seven of those women were found to have invasive breast cancer—and not only DCIS—in the samples analyzed after their breast cancers were removed.

The researchers did not say if any of the other 473 women in this study were later found to have invasive disease.

Conclusion: The researchers concluded there is a very small chance of breast cancer cells spreading to the lymph nodes in women with DCIS.

Therefore, lymph node removal should not be routinely done for women with just DCIS. Lymph node evaluation is recommended for women with DCIS mixed with invasive disease.

Take-home message: The decision to do a lymph node removal procedure for DCIS should be based on the full pathology report of the breast surgery.

In general, if you only have DCIS without any signs of invasion, then lymph node removal can be avoided.

If your pathology report reveals a number of features that may go along with an increased risk of lymph node involvement, then your surgeon may recommend a sentinel lymph node removal. Such factors can include:

• microinvasion,
• a significant amount of high grade comedo variety of DCIS,
• radiographic signs suggestive of a large amount of DCIS. For example: a mammogram may show wide-spread microcalcifications within and surrounding the known area of DCIS: an MRI might show areas of enhancement well beyond the known area of DCIS,
• young age at presentation (under 40 years) along with a significant area of involvement.

Discuss these factors with your surgeon and figure out whether any lymph node removal is right for YOU.

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