Radiation-related Quality of Life Parameters after Targeted Intraoperative Radiotherapy vs. Whole Breast Radiotherapy in Patients with Breast Cancer: Results from the Randomized Phase III Trial TARGIT-A

Partial breast irradiation for early breast cancer

BACKGROUND

Breast-conserving therapy for women with breast cancer consists of local excision of the tumour (achieving clear margins) followed by radiotherapy (RT). RT is given to sterilize tumour cells that may remain after surgery to decrease the risk of local tumour recurrence. Most true recurrences occur in the same quadrant as the original tumour. Whole breast radiotherapy (WBRT) may not protect against the development of a new primary cancer developing in other quadrants of the breast. In this Cochrane review, we investigated the delivery of radiation to a limited volume of the breast around the tumour bed (partial breast irradiation (PBI)) sometimes with a shortened treatment duration (accelerated partial breast irradiation (APBI)).

OBJECTIVES

To determine whether PBI/APBI is equivalent to or better than conventional or hypo-fractionated WBRT after breast-conserving therapy for early-stage breast cancer.

SEARCH METHODS

We searched the Cochrane Breast Cancer Group Specialized Register (4 May 2015), the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 5), MEDLINE (January 1966 to 4 May 2015), EMBASE (1980 to 4 May 2015), CINAHL (4 May 2015) and Current Contents (4 May 2015). We searched the International Standard Randomised Controlled Trial Number Register (5 May 2015), the World Health Organization's International Clinical Trials Registry Platform (4 May 2015) and ClinicalTrials.gov (17 June 2015). We searched for grey literature: OpenGrey (17 June 2015), reference lists of articles, several conference proceedings and published abstracts, and applied no language restrictions.

SELECTION CRITERIA

Randomized controlled trials (RCTs) without confounding, that evaluated conservative surgery plus PBI/APBI versus conservative surgery plus WBRT. Published and unpublished trials were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors (BH and ML) performed data extraction and used Cochrane's 'Risk of bias' tool, and resolved any disagreements through discussion. We entered data into Review Manager 5 for analysis.

MAIN RESULTS

We included seven RCTs and studied 7586 women of the 8955 enrolled.Local recurrence-free survival appeared worse for women receiving PBI/APBI compared to WBRT (hazard ratio (HR) 1.62, 95% confidence interval (CI) 1.11 to 2.35; six studies, 6820 participants, low-quality evidence). Cosmesis (physician-reported) appeared worse with PBI/APBI (odds ratio (OR) 1.51, 95% CI 1.17 to 1.95, five studies, 1720 participants, low-quality evidence). Overall survival did not differ with PBI/APBI (HR 0.90, 95% CI 0.74 to 1.09, five studies, 6718 participants, high-quality evidence).Late radiation toxicity (subcutaneous fibrosis) appeared worse with PBI/APBI (OR 6.58, 95% CI 3.08 to 14.06, one study, 766 participants, moderate-quality evidence). Acute skin toxicity appeared reduced with PBI/APBI (OR 0.04, 95% CI 0.02 to 0.09, two studies, 608 participants). Telangiectasia (OR 26.56, 95% CI 3.59 to 196.51, 1 study, 766 participants) and radiological fat necrosis (OR 1.58, 95% CI 1.02 to 2.43, three studies, 1319 participants) appeared worse with PBI/APBI. Late skin toxicity (OR 0.21, 95% CI 0.01 to 4.39, two studies, 608 participants) and breast pain (OR 2.17, 95% CI 0.56 to 8.44, one study, 766 participants) appeared not to differ with PBI/APBI.'Elsewhere primaries' (new primaries in the ipsilateral breast) appeared more frequent with PBI/APBI (OR 3.97, 95% CI 1.51 to 10.41, three studies, 3009 participants).We found no clear evidence of a difference for the comparison of PBI/APBI with WBRT for the outcomes of: cause-specific survival (HR 1.08, 95% CI 0.73 to 1.58, five studies, 6718 participants, moderate-quality evidence), distant metastasis-free survival (HR 0.94, 95% CI 0.65 to 1.37, four studies, 3267 participants, moderate-quality evidence), relapse-free survival (HR 1.36, 95% CI 0.88 to 2.09, three studies, 3811 participants), loco-regional recurrence-free survival (HR 1.80, 95% CI 1.00 to 3.25, two studies, 3553 participants) or mastectomy rates (OR 1.20, 95% CI 0.77 to 1.87, three studies, 4817 participants, low-quality evidence). Compliance was met: more than 90% of the women in all studies received the RT they were assigned to receive. We found no data for the outcomes of costs, quality of life or consumer preference.

AUTHORS' CONCLUSIONS

It appeared that local recurrence and 'elsewhere primaries' (new primaries in the ipsilateral breast) are increased with PBI/APBI (the difference was small), but we found no evidence of detriment to other oncological outcomes. It appeared that cosmetic outcomes and some late effects were worse with PBI/APBI but its use was associated with less acute skin toxicity. The limitations of the data currently available mean that we cannot make definitive conclusions about the efficacy and safety or ways to deliver of PBI/APBI. We await completion of ongoing trials.

Late radiation toxicity after intraoperative radiotherapy (IORT) for breast cancer: results from the randomized phase III trial TARGIT A

The randomized phase III trial TARGIT A showed non-inferiority regarding local control after intraoperative radiotherapy (IORT 20 Gy which was followed by whole breast radiotherapy (WBRT) in patients with risk factors only) in comparison to standard WBRT (50-56 Gy) after breast-conserving surgery in selected patients. This is the first analysis of long-term toxicities in the setting of TARGIT. Between 02/2002 and 12/2008, 305 patients were treated within TARGIT A (Arm A: n = 34 IORT, n = 20 IORT + WBRT for risk factors; Arm B WBRT: n = 55) or received IORT as a planned boost (control group: n = 196) at a single center. Toxicity was assessed according to the LENT SOMA scales. No significant differences were seen between Arm A and Arm B regarding fibrosis, breast edema, retraction, ulceration, lymphedema, hyperpigmentation, and pain. Arm A had significantly less telangiectases compared to Arm B (p = 0.049). In the subanalysis (Arm A IORT vs. Arm A IORT + WBRT vs. Arm B), fibrosis had a cumulative rate of 5.9 versus 37.5 versus 18.4 %, respectively (38.2 % IORT boost control group), at 3 years. No telangiectases were seen after IORT alone (0 % Arm A IORT vs. 17.5 % Arm A IORT + WBRT vs. 17.7 % Arm B). The hazard ratio of higher grade toxicity as first event was 0.46 (95 % CI, 0.26-0.83) for Arm A IORT as compared to Arm B (p = 0.010). No recurrences were seen after a median follow-up of 40 months (Arm A) and 42 months (Arm B). With its very low chronic skin toxicity rates and outstanding long-term results regarding toxicity and local control, IORT with 50 kV X-rays is a safe and effective method for treatment of selected breast cancer patients.