Clinical investigation
Breast
Targeted intraoperative radiotherapy (TARGIT) yields very low recurrence rates when given as a boost

https://doi.org/10.1016/j.ijrobp.2006.07.1378Get rights and content

Purpose: Patients undergoing breast-conserving surgery were offered boost radiotherapy with targeted intraoperative radiotherapy (TARGIT) using the Intrabeam system to test the feasibility, safety, and efficacy of the new approach.

Methods and Materials: We treated 302 cancers in 301 unselected patients. This was not a low-risk group. One-third of patients (98/301) were younger than 51 years of age. More than half of the tumors (172, 57%) were between 1 cm and 2 cm, and one-fifth (62, 21%) were >2 cm; 29% (86) had a Grade 3 tumor and, in 29% (87), axillary lymph nodes contained metastasis. After primary surgery, 20 Gy was delivered intraoperatively to the surface of the tumor bed, followed by external-beam radiotherapy (EBRT), but excluding the usual boost.

Results: The treatment was well tolerated. The follow-up ranged from 3 to 80 months (164 and 90 patients completed 2 and 3 years follow-up, respectively). Four patients (1.3%) had local recurrence. The Kaplan-Meier estimate of local recurrence is 2.6% (SE = 1.7) at 5 years. This compares favorably with the 4.3% recurrence rate in boosted patients from the EORTC boost study, in which only 8.1% patients were node-positive, as opposed to 29% in our series.

Conclusion: Targeted intraoperative radiotherapy combined with EBRT results in a low local recurrence rate. This could be attributed to both accurate targeting and timeliness of the treatment. These data support the need for a randomized trial to test whether the TARGIT boost is superior to conventional external boost, especially in high-risk women.

Introduction

Early local recurrences after breast-conserving surgery and postoperative radiotherapy for breast cancer most commonly occur in the vicinity of the primary tumor bed (1). A radiotherapy boost to the tumor bed is therefore part of standard treatment. However, accurate targeting of this boost can be difficult because of deformation and positional change of the postoperative breast, particularly because there is often a considerable delay between surgery and radiotherapy planning. A “geographical miss” occurs in 50–80% of patients (2, 3, 4) and this may contribute toward a proportion of local recurrences. Modern radiotherapy planning by computed tomography simulation, in which surgical clips are outlined, may be able to reduce this. However, a much simpler and direct method may be to use intraoperative radiotherapy.

We developed a novel technique of delivering intraoperative therapeutic irradiation that we call targeted intraoperative radiotherapy (TARGIT) (5, 6). With this technique, using the Intrabeam system, the target tissue—namely, the tumor bed—is wrapped around or conformed to the radiotherapy source, which delivers radiotherapy from within the breast, usually under the same anesthetic as the primary surgery. The procedure can be performed in a standard operating theater and adds 20 to 40 min to the operation time.

We are currently testing whether partial-breast irradiation, using this technique in selected patients, can replace conventional whole-breast external-beam radiotherapy (EBRT) in a multicenter randomized trial (7, 8). Centers participating in this trial initially treated a series of pilot cases to test the feasibility and safety of using the new technique of intraoperative radiotherapy supplemented by standard EBRT in patients with a high risk of local recurrence. This article describes the outcomes in relation to local recurrence, among the 301 consecutive patients in whom intraoperative radiotherapy was used as a tumor bed boost.

Section snippets

Methods and materials

The study protocol was approved by the local ethics committee in each center. Patients of any age suitable for breast-conserving surgery were approached and consented to participate in the pilot studies at each of the five centers. Tumors were unifocal on mammography up to 4 cm in diameter. There was no restriction by tumor type, tumor grade, receptor status, or axillary lymph node involvement. Each patient had her breast-conserving surgery as per local protocol—typically a wide local excision

Results

Between July 1998 and Aug 2005, 321 patients participated in this pilot study; 20 patients were excluded. One patient had multiple diffuse margin involvement and declined further surgery, 1 patient had bilateral prophylactic mastectomy (at her request), and 18 patients had further surgery for involved margins: 13 mastectomy and 5 re-excision. Thus, the total evaluable patients included in this study are 301. One patient had bilateral cancers treated, making the total number of cancers equal to

Discussion

This study demonstrates that radiotherapy targeted to the tumor bed, when it is most accessible at the time of surgery for the cancer, is associated with a low rate of local disease recurrence: 2.6% in actuarial terms at 5 years. The patient population in this series is representative of patients suitable for breast-conserving therapy (with T1 = 78% and T2 = 21%, Gr1 = 22%, Gr2 = 48.8%, Gr3 = 28.7%, and 29% node-positive). Approximately one-third (98/301) of these patients were younger than 51

References (16)

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    The technique and its clinical application were described by Vaidya.12,13 IORT given as a boost is an effective option for breast-conserving treatment.14 Data gathered in the Targeted Intraoperative radiotherapy (TARGIT) and Intraoperative radiotherapy with electrons (ELIOT) trials support the idea that some patients with breast cancer can be offered APBI as a sole radiation modality in BCT.15–17

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J.S.V., M.B., and J.S.T. conceived the study.

J.S.V., M.B., J.S.T., S.M., M.R., B.H., U.K., F.W., D.J., C.S., A.M.T., J.A.D. recruited and treated patients. J.S.V., M.B., J.S.T., S.M, M.R., B.H., U.K., F.W., D.J., C.S., A.M.T., J.A.D., E.H., and J.H. collected the data.

M.K., R.S., M.D., and F.M. were involved in later follow-up care.

J.S.V., O.M., S.M., U.K.T., T.C., and B.H. analyzed the data.

J.S.V. and S.M. wrote the first draft and all other authors contributed to the final manuscript.

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