ASCO 2010: Targeted intraoperative radiotherapy is as good as whole breast radiotherapy at reducing breast cancer recurrence

5 Jun 2010

Targeted intraoperative radiotherapy (TARGIT) for breast cancer—in which radiotherapy is confined to the area of the breast where the tumour has been removed—is as good as whole breast radiotherapy at reducing breast cancer recurrence, and can be carried out in one hospital visit. This could mean much more convenient care for breast cancer patients, as well as reduced waiting lists and substantial savings for health-care systems. The findings of the TARGIT-A study were presented at the American Society of Clinical Oncology (ASCO) meeting in Chicago, USA. The study is by Jayant S Vaidya, University College London, UK, and David Joseph, University of Western Australia, Perth, Australia, and colleagues from 28 centres from 9 countries.

After breast-conserving surgery, 90% of local recurrences occur very close to the removed tumour (called the index quadrant) despite the presence of multicentric cancers elsewhere in the breast. Thus, restriction of radiation therapy to the site of tumour removal (tumour bed) during surgery could be adequate for selected patients. In TARGIT-A, the authors compared targeted intraoperative radiotherapy with the conventional policy of whole breast external beam radiotherapy.

In this prospective, randomised, non-inferiority trial, women aged 45 years or older with invasive ductal breast carcinoma undergoing breast-conserving surgery were enrolled. Patients were randomly assigned in a 1:1 ratio to receive targeted intraoperative radiotherapy or whole breast external beam radiotherapy. Postoperative discovery of predefined factors (eg, lobular carcinoma) could trigger addition of external beam radiotherapy to targeted intraoperative radiotherapy (in around 15% of patients). The primary outcome was local recurrence in the conserved breast.

A total of 1113 patients were randomly allocated to targeted intraoperative radiotherapy and 1119 were allocated to external beam radiotherapy. Of 996 patients who received the allocated treatment in the targeted intraoperative radiotherapy group, 854 (86%) received targeted intraoperative radiotherapy only and 142 (14%) received targeted intraoperative radiotherapy plus external beam radiotherapy.1025 (92%) patients in the external beam radiotherapy group received the allocated treatment. At 4 years, there were six local recurrences in the intraoperative radiotherapy group and five in the external beam radiotherapy group. This translated to very similar recurrence rates in both groups: 1·20% in the targeted intraoperative radiotherapy and 0·95% in the external beam radiotherapy group. The frequency of any complications and major toxicity was similar in the two groups. For major toxicity, the rates were 3·3% in the targeted intraoperative radiotherapy group versus 3·9% in the external beam radiotherapy group. Radiotherapy toxicity (Radiation Therapy Oncology Group grade 3) was lower in the targeted intraoperative radiotherapy group (0·5%) than in the external beam radiotherapy group (2·1%).

While optimistic about the results, the authors caution that the results are only applicable to women with a profile similar to those in TARGIT-A. Patients aged 45 years or over who had early invasive breast cancer suitable for breast conserving surgery were eligible to participate and 82% of patients were younger than 70 years old.

The authors say: "In addition to the obvious benefits of completing all the necessary radiotherapy in a single session at the time of surgery, targeted intraoperative radiotherapy almost completely avoids irradiation of the intrathoracic structures such as the heart, lung, and oesophagus. Consequently, the damage to these structures, which can occur even with modern external beam radiotherapy, will have been avoided."

They add: "A crucial issue in understanding this trial centres on the benefits to the patient and the effect on the workload of a radiotherapy centre. Treatment of patients with breast cancer accounts for about a third of the workload of radiotherapy departments in some parts of the world and contributes substantially to the unacceptable waiting lists seen in many oncology departments worldwide. In countries such as the UK where the waiting list for postoperative radiotherapy could rapidly diminish with use of targeted intraoperative radiotherapy, we estimate savings of around £15,000,000 (US$23,000,000) a year."

They conclude: "For selected patients with early breast cancer, a single dose of radiotherapy delivered at the time of surgery by use of targeted intraoperative radiotherapy should be considered as an alternative to external beam radiotherapy delivered over several weeks."

In an accompanying comment, Dr David Azria, Department of Radiation Oncology and INSERM U896, CRLC Val d'Aurelle, Montpellier, France; and Dr Céline Bourgier, Department of Radiation Oncology, Institut Gustave Roussy, Villejuif, France, say: "We still await long-term follow-up and the results of another randomised trial from the National Surgical Adjuvant Breast and Bowel Project B-39. Nevertheless, in the elderly, we are already convinced that accelerated partial-breast irradiation is the new standard and intraoperative radiotherapy an excellent approach."


Source: Lancet Oncology