The results of a new trial presented at the American Society of Clinical Oncology annual meeting in Chicago indicate that partial breast irradiation performed immediately after lumpectomy may be as safe and effective as the weeks of radiation therapy that breast cancer patients typically undergo. The trial was designed to compare partial breast irradiation with standard whole breast radiation treatment after lumpectomy in patients at least 45 years old with invasive ductal breast cancer. After lumpectomy, 90% of local recurrences occur within the same quadrant of the breast in which the cancer was first diagnosed. Therefore, restricting radiation therapy to the immediate area around the tumor bed after removal of the primary tumor may be adequate. The TARGIT-A trial was initiated in March 2000. TARGIT-A uses a probe to deliver a high dose of radiation directly into the breast where the tumor has been removed by lumpectomy and while the patient is still under anesthesia. The trial compared TARGIT to standard whole breast external beam radiotherapy after breast conserving surgery in 2,232 patients with invasive ductal carcinoma. The primary outcome measure evaluated was local recurrence. Median age at enrollment was 63 years, median tumor size was 13mm, and positive lymph nodes were found in 17% of the patients. The participants have been followed for a median period of 24.6 months to date (maximum 10 years).

Wound breakdown or delayed healing was reported in 28 of the TARGIT group and grade 3 radiation-related toxicity occurred in six women. This compares with wound healing problems in 20 and grade 3 toxicity in 21 of the whole breast radiotherapy group. However, overall local toxicity was equivalent (34 of the 1,092 TARGIT study group compared to 41 of the 1,096 whole breast radiotherapy group). The Kaplan-Meier estimate of local recurrence in the breast was 0.31% for TARGIT compared to 0.29% for whole breast radiotherapy at 24 months. The authors conclude that in the TARGIT group, the radiotherapy toxicity was significantly lower than in the whole breast external beam radiotherapy group, while the slight increase in wound complications was not statistically significant. This suggests that local control with TARGIT partial breast irradiation is comparable to whole breast external beam radiotherapy as of the two-year mark. Longer term follow-up is essential since cancer can recur after many years and a large dose of radiation can cause tissue damage that might not become apparent for three to 10 years.