Jay R Harris, MD Professor and Chair Department of Radiation Oncology Dana-Farber Cancer Institute Brigham and Women’s Hospital Harvard Medical School

Edited comments by Dr Harris

Accrual to RTOG-9915/SWOG-S9927: Postmastectomy radiation therapy versus observation in women with one to three positive nodes

It’s pretty clear that women with four or more positive nodes should receive postmastectomy radiation therapy, and women with negative nodes — unless the margins are positive — should not receive radiation therapy. The uncertainty is in women with one to three positive nodes. Unfortunately, accrual to the trial addressing this issue has been extremely slow.

We participated in the trial but found it very hard to do in Boston. I think it suggests that patients and their physicians feel strongly that they should or should not receive radiation. Unlike a trial comparing a medication to a placebo, in which patients don’t know what they are receiving, patients know when they’re being treated with radiation. This trial might actually close without an answer, which would be very unfortunate.

Outside of participating in a clinical trial, we try to use other factors to sway us one way or the other regarding the administration of radiotherapy. The most obvious factor is whether the woman has three positive nodes or one. We are also convinced that lymphatic vessel invasion, tumor size, closeness to the margins of resection and young patient age are important prognostic factors with regard to local recurrence.

Potential risks of postmastectomy radiation therapy

Long-term cardiac toxicity is the biggest concern we’ve had over the years, particularly for tumors in the left breast. Fortunately, technology has come to our aid, and radiation treatment is now planned and simulated by CT scan, allowing us to contour the heart and devise beams to minimize treating the heart. Use of CT simulation is rapidly becoming standard across the country. Patients and physicians should ask for this as a part of their treatment planning.

The other significant issue is increased risk of arm edema. If an axillary dissection has been performed, the risk of edema is in the range of 10 to 15 percent. This risk may increase with radiotherapy, depending on how the radiotherapy is done. It is critical whether or not the radiation is applied to the dissected area or to the adjacent nodal areas. You can double the risk of arm edema if you add radiation after a fairly thorough dissection; however, if it’s a more limited dissection and radiation stays away from that area, the increase in arm edema is quite modest.

Postmastectomy radiation therapy and breast reconstruction

There is a negative interaction between postmastectomy radiation therapy and implants. There is a significant problem with cosmetic results, and the chances for encapsulation and fat necrosis are significantly increased with irradiation of implants. We tell our patients that there is a 50 percent chance that they will need to remove the implant. In addition, it is difficult to contemplate putting an implant in after radiation. Although we're still learning in this area, a common belief is that these patients should have flap reconstruction. Most plastic surgeons would rather bring in fresh tissue with a fresh blood supply. Our preliminary findings suggest that radiation therapy in a patient with a flap has a much more modest effect on the cosmetic result than radiation therapy in a patient with an implant.

We don’t know the optimal timing of radiation therapy with respect to the flap; however, based on anecdotal information, the preference is to do the radiation first and then perform flap reconstruction. Within our medical community, if there’s a hint that the patient might need radiation, they’ll be told to hold off on reconstruction. Sentinel lymph node biopsy is helpful in that we are obtaining some indication about the nodal status earlier on, which facilitates decision-making.

Status of research on partial breast irradiation

I sometimes joke that McDonald’s is one of America’s great contributions to world civilization — fast is good. There’s an interest in finding a way to do radiation in less than six weeks. One method of partial breast irradiation involves the surgeon putting a balloon into the biopsy cavity soon after the resection and using highdose- rate radiation on an outpatient basis twice a day for five days to deliver radiation to a local area.

We have very limited information about this procedure, but there is a great deal of interest from patients. It has received FDA approval based on shortterm Phase I data, and many people around the country are already certified or trained. The NSABP is considering looking at partial breast irradiation in a randomized trial, which would be wonderful. We are finalizing our own Phase I study at Dana-Farber and Brigham and Women’s Hospital in a lowrisk group of older node-negative patients who do not have an extensive intraductal component or lymphatic vessel invasion. Our view as a group is that right now, based on the available data, we will only use this approach as part of a protocol and carefully follow those patients.

The biggest surgical issue seems to be the proximity to the skin, because if there isn’t much distance from the balloon to the skin, the skin may receive a substantial dose of radiation that could result in cosmetic problems. This would defeat the purpose of this technology: to attain local control and a cosmetic result as good as that of six weeks of external beam radiation.

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