Targeted Intraoperative Radiotherapy (TARGIT) Clinical Trial Outcomes Demonstrate the Potential for Single-Dose Radiation Therapy to Become the New Standard of Care in Breast Cancer Therapy

TARGIT-A, the largest randomized clinical trial conducted in the field of intra-operative radiotherapy (IORT) for the treatment of breast cancer, has achieved clinical results that may significantly broaden the use of a shorter and easier radiation therapy method for women battling breast cancer worldwide. With up to ten-year follow-up data, the TARGIT-A single-dose IORT clinical trial results will be presented for the first time during American Society of Clinical Oncology's (ASCO's) 46th Annual Meeting. These TARGIT study results have also been published as a fast-tracked paper in The Lancet.

The TARGIT-A (TARGeted Intra-operative radiation Therapy) multicenter clinical trial1 was launched in 2000 in which 28 centers from 9 countries participated. TARGIT-A trial compared standard whole breast external beam radiotherapy (EBRT) with single-dose targeted intra-operative radiotherapy (TARGIT2,3) using INTRABEAM® after breast conserving surgery in patients aged 45 years and over with invasive ductal carcinoma. Local recurrence was the primary outcome measure1. The original accrual goal of 2232 patients in the TARGIT-A trial, the first randomized clinical trial on partial breast irradiation using intra-operative radiotherapy, was reached in April 2010.

The results4,5 demonstrated the therapeutic equivalence of TARGIT using the INTRABEAM® system: The Kaplan-Meier estimate of local recurrence in the breast was 1.2% (CI 0.53-2.71) for TARGIT versus 0.95% for EBRT (CI 0.39-2.3) at 4 years. The absolute difference in local recurrence in the conserved breast was 0.25% (95%CI -1.04% to 1.54%.) i.e., the absolute difference in local recurrence rate could be at most 1.5% worse or at most 1.0% better with TARGIT than with EBRT. Median age was 63 and 83% patients were below 70 years, median tumor size was 12mm, and 17% of the patients were lymph node positive.

In terms of toxicity, TARGIT performed well in comparison with conventional therapy: The Radiation Therapy Oncology Group (RTOG) grade 3 toxicity (nil grade 4) was only seen in 0.5% patients in the TARGIT group vs. 2.1% patients in the EBRT group, while incidence of seroma requiring aspiration was higher in the TARGIT group (2.1% vs. 0.8%). Overall local toxicity as well as major complication rate was equivalent between the TARGIT group and the EBRT group4.

"It is a privilege to have the opportunity to reveal these positive clinical outcomes to my esteemed colleagues and to the millions of people who will ultimately benefit from advances in breast cancer treatment," said leading British oncologist Michael Baum, Professor Emeritus of surgery at the University College London and chairman of the TARGIT-A trial. "It is the sincere hope of the TARGIT group that these results influence a paradigm shift from conventional radiation approaches to single-dose treatment for eligible patients."

Jayant S Vaidya, who is a co-inventor of the TARGIT technique and who designed the trial alongside Professor Baum and Professor Jeffrey Tobias, added, "The first is that TARGIT single-dose treatment can replace whole breast radiotherapy approaches which are time-consuming and uncomfortable for the patient. The second is that a much smaller radiation dose can be adequate to achieve similar outcomes, thereby reducing toxicity and eliminating certain side affects, such as cosmetic reactions."

TARGIT single-dose treatment with the INTRABEAM® system provides increased patient convenience: three- to six weeks of radiotherapy may be replaced by a one-day treatment (approximately 30 minute treatment time). This approach may also make radiation therapy available for patients who do not have access today, e.g., in developing countries. Also, in industrialized countries, many women do not undergo the recommended breast radiation due to inconvenience or cost. TARGIT single-dose treatment with the INTRABEAM® system is considerably less expensive than conventional radiation therapy4, which it could replace.

"In addition to the profound benefits that TARGIT single-dose treatment offers to breast cancer patients, it can also be performed within any hospital or treatment centre at the time of surgery," added Professor Frederik Wenz, head of radiation oncology at the University Medical Center Mannheim. "It is our sincere hope that single-dose radiation therapy will become more widely available to patients who do not have acceptable access to treatment today."

Source: Lancet