Delivering radiation to the tissues surrounding a breast cancer tumor immediately after it is removed now has the support of a positive clinical trial -- but doctors say much more proof is still needed before it can be considered anything but experimental.
The procedure is known by the acronym TARGIT -- short for targeted intraoperative radiation therapy. Doctors expose the tissues around the site of a tumor to a short period of radiation during breast-conserving surgery. The idea is to target the tissues that where the cancer has the highest risk of returning.
But breast cancer experts cited concerns about the low radiation dose used in the procedure, the relatively short follow-up in the clinical trial, and the expense of the equipment. Most said they would not offer the procedure outside of a clinical trial.
"It is way too early to draw solid conclusions in order to safely recommend targeted intraoperative radiotherapy to any group of patients based on these immature data," according to Dr. Henry Mark Kuerer of M.D. Anderson Cancer Center in Houston, Texas.
The data come from a large randomized trial that found the process to be at least as effective as standard radiation therapy.
The procedure could help patients avoid the lengthy and often difficult process of whole-breast radiation therapy by combining both lumpectomy and radiation in a single procedure, according to Jayant Vaidya of University College London. Vaidya was lead author on the study, published online in The Lancet and presented at the same time at the Chicago meeting of the American Society of Clinical Oncology.
They argued that the data are sufficiently strong that the process "should be considered as an alternative to external beam radiotherapy delivered over several weeks."
But most experts who responded to a query about the issue begged to differ.
The therapy "would be welcomed by women with early breast cancer," Kuerer said in an email to ABC News, but the data aren't yet strong enough. Specifically, he said, the average follow-up for patients was only two years, and fewer than 20 percent were followed for longer than four years.
"For breast cancer, this very short follow-up period is considered unacceptably small to draw conclusions about local recurrence," he said.
Indeed, the follow-up is so short, according to Dr. William Wood of Emory University in Atlanta, that the results remind him of the answer given by the man who had jumped from a skyscraper and was asked as he passed the 20th floor how he was enjoying the trip -- "exhilarating!"
The current data, he said in an email, "are like that mythic interview" since problems would take 10 or more years to show up.
Dr. Len Lichtenfeld, deputy chief scientific officer for the American Cancer Society, also asked if the follow-up was adequate but told MedPage Today that's not the only issue with the study.
Lichtenfeld noted that two major centers -- contributing more than 500 patients to the 2,232-patient study -- were allowed to decide how to treat patients after their removed tumor had been tested pathologically.
That, he said, raises the "potential of selection bias" -- in other words, that some women who got the TARGIT treatment were selected because they would probably do well.
Indeed, Lichtenfeld said, most of the women in the study had favorable characteristics, making it difficult to know how widely the findings apply.