Two Types of Radiation Therapy Yield Same Appearance
Cosmetic outcomes appear the same whether breast cancer patients get radiation therapy directly to the tumor bed during surgery or afterward with the conventional external beam approach, according to a randomized trial.
Objective measurement based on symmetry, color, and scarring revealed good to excellent cosmesis at two years in 78% of intraoperative radiation therapy and 74% of external beam cases (P=0.65), Norman Williams, PhD, of University College London, and colleagues reported here at the ASCO Breast Cancer Symposium.
Three year results were likewise similar between groups (P=0.11) in the international TARGIT trial, which is expected to yield its first safety results at the primary ASCO meeting next year, Williams said.
In the U.S. where six weeks of daily external beam radiation is standard, a single fraction of intraoperative radiation is still considered highly experimental, although it’s more accepted in Europe, commented Eleanor Harris, MD, of the Moffitt Cancer Center in Tampa, Fla.
Limiting radiation exposure outside of the area with highest tumor recurrence risk is anticipated to minimize damage to heart and lung, potentially making it a safer strategy than whole-breast external beam radiation, she said.
Convenience, though, is the primary factor that makes it so attractive, added Stephen Edge, MD, of the Roswell Park Cancer Institute in Buffalo, New York.
Thus, the preliminary findings on equal cosmesis between the two radiation approaches were reassuring, said Peter Y. Chen, MD, of the William Beaumont Hospital, which pioneered use of accelerated partial breast irradiation techniques in the U.S.
The TARGIT trial was designed to determine if intraoperative radiotherapy provides local relapse control equivalent to four to six weeks of conventional external beam radiation in early breast cancer.
Intraoperative radiotherapy patients were treated with the Intrabeam device, which Williams described as a portable x-ray machine that doesn’t require a specially shielded operating theater. Some of these women were randomized to intraoperative radiotherapy after their initial breast-conserving surgery and had to have a second surgery, which was necessary because of negative margins or pathology concerns in only about 10%, Williams said.
One of the anticipated effects of this was delayed wound healing, he said.
So a subset of 105 patients in the trial were assessed for cosmesis with digital photographs run through a software program that calculated symmetry, color, and scar differences between each woman’s breasts to determine a composite cosmetic outcome score ranging from excellent to poor.
At two years, only 21.8% of intraoperative radiotherapy-treated patients and 26% of conventional radiotherapy-treated patients had a score in the “fair” or “poor” range.
At three years, poor to fair cosmesis was seen in just 13.8% of the intraoperative radiation group compared with 30% of the external beam radiation group, though not a significant difference.
If the main trial results show equal efficacy between the two radiation strategies in early breast cancer, Williams said, intraoperative therapy will win out.
However, although intraoperative therapy has at least theoretical advantages for patient and the healthcare team, he noted that these don’t always look as good in practice. For example, patients in the trial who get intraoperative radiotherapy during initial surgery and then are found to have higher-risk pathology, such as lobular carcinoma, go on to external beam radiation as well per protocol.
“We have to be careful that we don’t describe [intraoperative radiation] as a one-stop cure-all without describing some of the potential downsides of it,” Williams said.