Edited comments by Dr Borgen

Sentinel node biopsy: The standard of care?

In experienced hands, sentinel node biopsy is absolutely a standard of care. The evidence is overwhelming. There are over 50 institutional series of 6,000 patients who had back-up axillary dissections. Sentinel node biopsy is actually more accurate than providing the pathologist 20 lymph nodes from an axillary dissection.

The question should not be whether sentinel node biopsy is an accepted standard of care, but rather, does each surgeon know how to do it, and is he or she comfortable accepting a sentinel lymph node biopsy result?

Patient selection is important — sentinel node biopsy is not for everyone. For example, if the tumor is very high in the tail of the axilla, sentinel node mapping can be problematic. Other examples of women who are not good candidates for sentinel node biopsy are patients with two cancers in one breast, clinically palpable nodes and those who have received neoadjuvant chemotherapy.

Parenchymal versus intradermal tracer injections for sentinel node biopsy

We started doing sentinel node biopsy with parenchymal injections of tracer in 1995, and in 1998 we began studying the intradermal injection. This became our standard of care in late 1999 because of the advantages to the intradermal injection.

First, the skin lymphatics drain much faster than the parenchymal lymphatics. Second, we can use a physician extender to inject the tracer — the surgeon doesn’t have to go to nuclear medicine to do the injection. And third, we can use two-thirds less radioactivity when injecting into the skin. The radioactivity in the lymph node is lower, and there is less radiation exposure to pathologists handling these nodes.

This intradermal technique is now being done widely. Kelly McMasters* from Louisville studied surgeons and found that the learning curve was far easier, and the success rate was much higher with intradermal injections of tracer than it was with intraparenchymal injections.

*McMasters KM. Ann Surg 2001;233(5):676-87.

Intraoperative radiation therapy

We have an active research protocol looking at intraoperative radiation therapy to the quadrant of the breast with the cancer. This would be an enormous advantage if we can prove that it is as safe and efficacious, over six weeks of external beam radiation therapy. It is one-third as expensive, completed in 30 minutes rather than six weeks, and patients can start systemic therapy immediately. We are very enthusiastic about the idea of jointly doing surgery and radiation therapy.

Veronesi’s group looked at their first 200 cases, using a different technology than we have in this country. Their early data shows local recurrence rates similar to rates with external beam therapy. Local recurrences overwhelmingly occur near the original cancer, so the idea of trying to not radiate the other three quadrants of the breast makes a lot of sense.

There also have been great improvements in systemic therapy, which affects the remainder of the breast. My early guess is that intraoperative radiation therapy will be as effective as external beam and will be embraced rapidly once we work out the optimal technology.

Evaluating results of the ATAC adjuvant trial in postmenopausal women

The headline news from the ATAC trial is that anastrozole looks better than tamoxifen, and the combination does not look any different than tamoxifen. This confirms the findings in the stage IV setting showing that anastrozole was at least as good as, if not better, than tamoxifen and certainly had a more favorable side-effect profile.

We have been using aromatase inhibitors at Memorial Sloan- Kettering since 1995 when anastrozole was approved, and these agents are very well tolerated. They don’t cause nearly the side effects that our patients on tamoxifen tell us about, and we’ve been enthusiastic about using them.

Future trials of aromatase inhibitors in DCIS

I’m confident that DCIS will be the first arena that we move into with the aromatase inhibitors beyond invasive breast cancer. The RTOG has a DCIS trial looking at women with small favorable lesions randomized to radiation or not. This trial requires that all women take tamoxifen. They couldn’t accrue enough patients, and ultimately they had to remove the tamoxifen requirement. This gets back to tamoxifen’s image problem. I think that the community will embrace an aromatase inhibitor trial in DCIS. The prospect of an agent with a better side-effect profile than tamoxifen is very exciting in both the DCIS and the chemoprevention settings.

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