Sentinel Node Biopsy

16. Is sentinel node biopsy a good option for a . . .

A. 56-year-old woman with two centimeter BCA in upper outer quadrant and one centimeter BCA in lower inner quadrant?

B. 42-year-old woman with three centimeter BCA who wants mastectomy with immediate reconstruction using TRAM flap?

C. 55-year-old woman with two centimeter BCA high up in the upper outer quadrant in the tail of Spence?

Patrick Borgen, MD

Case A.
In general, I would say that SNB is not a good option for this patient. And certainly at the time that this meeting was held the answer should have been no. There has been some pretty compelling data that different quadrants may actually have different sentinel nodes. So, I think that in general someone with two cancers, we would probably do a sentinel node, but then do some backup dissection as well. I don't think we're 100 percent into the idea that there is one sentinel node for the breast.

Case B.
Absolutely a good option. There's precious little data that tumor size affects the accuracy of sentinel node mapping. And certainly it's as appropriate with mastectomy as it is with breast conservation.

Case C.
It's a good option, but the fact is that the higher the tumor is in the tail of the breast (i.e., how close it is to the actual sentinel node) the more technically demanding and difficult it becomes. So, I would say the higher a breast cancer is —if you're going to trust the sentinel node — you've got to really have a good deal of experience with it in order to rely on it. Anytime you can avoid doing a node dissection for whatever reason, it's very much in the patient's interest. It's just that here the problem is that the proximity of the tumor in the sentinel node could be very, very close, which makes the technical part of finding believable sentinel nodes more difficult.

What we do is we inject the tracer into the skin and then, as part of the lumpectomy or the re-excision, that skin is totally excised. So, the tissue —where the tracer was— is removed from the field. That removes 98 percent of your background noise. You inject a tiny amount of blue dye —instead of 2 or 3 cc's, it's .2 or .3 cc's —so there's just a tiny amount of blue in the tissues. And then you dissect very, very carefully, starting at the tumor bed, going progressively through until you hit that sentinel node. It's really the blue dye, because very often there's so much scatter radiating.

17. Is sentinel lymph node biopsy now a standard of care for patients with clinical T1NO cancers?

Patrick Borgen, MD

In the hands of a surgeon experienced in the technique who has validated his/her own experience, it certainly is the standard of care. If you look at the two trials that are out there, the American College trial accepts a negative sentinel node in the control arm. That's what they're calling the standard of care. The NSABP, in their trial, would argue no, it's not; you need to do a backup dissection. In about 40 studies now, involving about 6,000 patients around the world, the data is identical. The anatomic hypothesis, to me, has been answered. The question is, "Can you find the sentinel node or find all the sentinel nodes?" And that's really the remaining challenge. If the trials answer anything, it will be technical issues on how you find the sentinel node.

18. Do you believe sentinel lymph node biopsy is useful in patients with DCIS?

Patrick Borgen, MD

We know that one percent of patients with DCIS have metastatic disease in nodes, and we know that a proportion of that one percent will die of breast cancer. We also know that micro-invasion is frequently missed in the breast and, frankly, sometimes their cultivation is missed. So, the real question is, "Does the end justify the means?" We've shown a 7 to 8 percent rate of IHC positivity in sentinel nodes in very high-risk DCIS. That seven percent is higher than what you see clinically. We don't see seven percent of people reccurring in the axilla.

I think that this is a research tool in DCIS. It is fodder for a trial, but I don't think that it should be used routinely in the management of a patient with DCIS.

Some situations where we might use SNB would be palpable DCIS, where you have a reasonably high rate of finding invasion on the final pathology. Another instance where SNB might be done is if a mastectomy is done, where there's a reasonably high chance of finding invasion and the bridge of mapping has been burned. You can't go back and map that patient post-mastectomy. So, many patients with a broad range of DCIS who get a mastectomy will have mapping done here. But I think it's an important research question, and I don't think the standard at this point is to do sentinel node mapping in DCIS.

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