An international randomised controlled trial to compare TARGeted Intraoperative radioTherapy (TARGIT) with conventional postoperative radiotherapy after breast-conserving surgery for women with early-stage breast cancer (the TARGIT-A trial)

Abstract

BackgroundBased on our laboratory work and clinical trials we hypothesised that radiotherapy after lumpectomy for breast cancer could be restricted to the tumour bed. In collaboration with the industry we developed a new radiotherapy device and a new surgical operation for delivering single-dose radiation to the tumour bed – the tissues at highest risk of local recurrence. We named it TARGeted Intraoperative radioTherapy (TARGIT). From 1998 we confirmed its feasibility and safety in pilot studies.ObjectiveTo compare TARGIT within a risk-adapted approach with whole-breast external beam radiotherapy (EBRT) over several weeks.DesignThe TARGeted Intraoperative radioTherapy Alone (TARGIT-A) trial was a pragmatic, prospective, international, multicentre, non-inferiority, non-blinded, randomised (1 : 1 ratio) clinical trial. Originally, randomisation occurredbeforeinitial lumpectomy (prepathology) and, if allocated TARGIT, the patient received it during the lumpectomy. Subsequently, the postpathology stratum was added in which randomisation occurredafterinitial lumpectomy, allowing potentially easier logistics and a more stringent case selection, but which needed a reoperation to reopen the wound to give TARGIT as a delayed procedure. The risk-adapted approach meant that, in the experimental arm, if pre-specified unsuspected adverse factors were found postoperatively after receiving TARGIT, EBRT was recommended. Pragmatically, this reflected how TARGIT would be practised in the real world.SettingThirty-three centres in 11 countries.ParticipantsWomen who were aged ≥ 45 years with unifocal invasive ductal carcinoma preferably ≤ 3.5 cm in size.InterventionsTARGIT within a risk-adapted approach and whole-breast EBRT.Main outcome measuresThe primary outcome measure was absolute difference in local recurrence, with a non-inferiority margin of 2.5%. Secondary outcome measures included toxicity and breast cancer-specific and non-breast-cancer mortality.ResultsIn total, 3451 patients were recruited between March 2000 and June 2012. The following values are 5-year Kaplan–Meier rates for TARGIT compared with EBRT. There was no statistically significant difference in local recurrence between TARGIT and EBRT. TARGIT was non-inferior to EBRT overall [TARGIT 3.3%, 95% confidence interval (CI) 2.1% to 5.1% vs. EBRT 1.3%, 95% CI 0.7% to 2.5%;p = 0.04; Pnon-inferiority = 0.00000012] and in the prepathology stratum (n = 2298) when TARGIT was given concurrently with lumpectomy (TARGIT 2.1%, 95% CI 1.1% to 4.2% vs. EBRT 1.1%, 95% CI 0.5% to 2.5%;p = 0.31; Pnon-inferiority = 0.0000000013). With delayed TARGIT postpathology (n = 1153), the between-group difference was larger than 2.5% and non-inferiority was not established for this stratum (TARGIT 5.4%, 95% CI 3.0% to 9.7% vs. EBRT 1.7%, 95% CI 0.6% to 4.9%;p = 0.069; Pnon-inferiority = 0.06640]. The local recurrence-free survival was 93.9% (95% CI 90.9% to 95.9%) when TARGIT was given with lumpectomy compared with 92.5% (95% CI 89.7% to 94.6%) for EBRT (p = 0.35). In a planned subgroup analysis, progesterone receptor (PgR) status was found to be the only predictor of outcome: hormone-responsive patients (PgR positive) had similar 5-year local recurrence with TARGIT during lumpectomy (1.4%, 95% CI 0.5% to 3.9%) as with EBRT (1.2%, 95% CI 0.5% to 2.9%;p = 0.77). Grade 3 or 4 radiotherapy toxicity was significantly reduced with TARGIT. Overall, breast cancer mortality was much the same between groups (TARGIT 2.6%, 95% CI 1.5% to 4.3% vs. EBRT 1.9%, 95% CI 1.1% to 3.2%;p = 0.56) but there were significantly fewer non-breast-cancer deaths with TARGIT (1.4%, 95% CI 0.8% to 2.5% vs. 3.5%, 95% CI 2.3% to 5.2%;p = 0.0086), attributable to fewer deaths from cardiovascular causes and other cancers, leading to a trend in reduced overall mortality in the TARGIT arm (3.9%, 95% CI 2.7% to 5.8% vs. 5.3%, 95% CI 3.9% to 7.3%;p = 0.099]. Health economic analyses suggest that TARGIT was statistically significantly less costly than EBRT, produced similar quality-adjusted life-years, had a positive incremental net monetary benefit that was borderline statistically significantly different from zero and had a probability of > 90% of being cost-effective. There appears to be little uncertainty in the point estimates, based on deterministic and probabilistic sensitivity analyses. If TARGIT were given instead of EBRT in suitable patients, it might potentially reduce costs to the health-care providers in the UK by £8–9.1 million each year. This does not include environmental, patient and societal costs.LimitationsThe number of local recurrences is small but the number of events for local recurrence-free survival is not as small (TARGIT 57 vs. EBRT 59); occurrence of so few events (< 3.5%) also implies that both treatments are effective and any difference is unlikely to be large. Not all 3451 patients were followed up for 5 years; however, more than the number of patients required to answer the main trial question (n = 585) were followed up for > 5 years.ConclusionsFor patients with breast cancer (women who are aged ≥ 45 years with hormone-sensitive invasive ductal carcinoma that is up to 3.5 cm in size), TARGIT concurrent with lumpectomy within a risk-adapted approach is as effective as, safer than and less expensive than postoperative EBRT.Future workThe analyses will be repeated with longer follow-up. Although this may not change the primary result, the larger number of events may confirm the effect on overall mortality and allow more detailed subgroup analyses. The TARGeted Intraoperative radioTherapy Boost (TARGIT-B) trial is testing whether or not a tumour bed boost given intraoperatively (TARGIT) boost is superior to a tumour bed boost given as part of postoperative EBRT.Trial registrationCurrent Controlled Trials ISRCTN34086741 and ClinicalTrials.gov NCT00983684.FundingUniversity College London Hospitals (UCLH)/University College London (UCL) Comprehensive Biomedical Research Centre, UCLH Charities, Ninewells Cancer Campaign, National Health and Medical Research Council and German Federal Ministry of Education and Research (BMBF). From September 2009 this project was funded by the NIHR Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 20, No. 73. See the NIHR Journals Library website for further project information.

The INTRABEAM® Photon Radiotherapy System for the adjuvant treatment of early breast cancer: a systematic review and economic evaluation

“…The planned follow-up for trial participants was at least 10 years. 69 Median follow-up achieved for the most recent 2014 publication 65 is 2 years 5 months.…”

“…The trial protocol specifically defined early invasive breast cancer as T1 and small T2, N0-1, M0. 69 The initial trial publication 64 stipulated the pre-operative diagnosis of lobular carcinoma as a single exclusion criterion, although the trial protocol specified additional exclusion criteria. 69 Furthermore, because the trial was pragmatic, each participating centre had the option to predefine more restrictive entry criteria than in the core protocol (e.g.…”

“…The risk of bias due to selective reporting was deemed low as all outcomes specified in the trial protocol 69 were reported in either the original or updated publication. 64,65 No other sources of bias in the total trial population were identified.…”

“…Recurrence was defined as a recurrent tumour in the ipsilateral breast and was confirmed pathologically by clinical examination and cytology or biopsy. 69 The most recent data from the 2014 65 publication are shown, which were not expressed in terms of disease-free survival. Results are presented in Tables 9 and 10 and show data for the whole cohort and for the two pre-specified randomisation strata (pre pathology and post pathology) representing the different timings in delivery of INTRABEAM therapy.…”

Could radiotherapy be omitted in elderly patients receiving breast conserving surgery?

“…In this regard, Bekelman et al 24 reported an increase of use of hypofractionation for breast cancer in the US from 10.6% in 2008 to 34.5% in 2014 24 . The calculation of adjusted mean total healthcare expenditures in the first year after diagnosis was highly relevant, resulting as $28,747 for hypofractionation vs $31,641 for conventional breast irradiation (D$2,894; p < .001), representing a decrease of 10%, by reducing the number of fractions from 25-39 to 11-24. In terms of irradiation modality, the multi-center international TARGIT-A trial 25 has recently shown that x-rays intraoperative radiotherapy (IORT) in single shot was less costly than EBRT and produced slightly more QALYs than conventional radiotherapy. The authors underline that "TARGIT had a positive incremental net monetary benefit that was borderline statistically" and "when TARGIT was used instead of conventional radiotherapy in suitable patients (age >45 years), it might potentially reduce costs to healthcare providers by £8-9.1 million each year".…”