ROYAL OAK, MichInterstitial implants that deliver radiation therapy
to the tumor bed alone after lumpectomy have been well tolerated with no
significant acute or late toxicity in the first 50 patients in a Michigan
study. In addition, with three years' median follow-up, no patients have
recurred locally or distantly.
"It's still early, but we're quite encouraged with the results
so far," Vinay Sharma, MD, a brachytherapy fellow at William Beaumont
Hospital, said at a poster presentation of the study, which was conducted
by Frank Vicini, MD, and colleagues. [See page 10 for a report on intraoperative
external beam radiation in this setting.]
The pilot study, begun in March 1993, includes selected patients with
early-stage breast cancer treated with breast-conserving therapy. Eligible
patients had tumors less than 3 cm, margins clear by 2 mm, no extensive
intraductal component, a breast technically suitable for implant, and three
or fewer involved nodes.
Implants Loaded into Catheters
Patients received a 50 Gy dose to the tumor bed over a 96-hour period.
The implants, radioactive iodine 125 seeds, are loaded into catheters placed
within the breast. About 30% of the time, the implants are placed at the
time of re-excision. "In that setting, the tumor cavity is open and
we see exactly where we're putting our needles," Dr. Sharma said.
The other 70% of the time, he said, seed implantation is done as a separate
operation or at the time of an axillary lymph node dissection "and
then we're dealing with a closed cavity."
In these cases, the researchers use three-dimensional (3D) computed
tomography and ultrasound computer reconstructions to help guide their
placement of the needles.
The researchers conclude that the brachytherapy technique may provide
a safe, quick, and effective alternative to standard external beam radiation
The implant method significantly decreases patient inconvenience and
reduces delays in the initiation of systemic therapy, Dr. Sharma said.
He noted, however, that longer follow-up will be needed to establish whether
this approach is equivalent in efficacy to that of standard post-lumpectomy
external beam radiation therapy.