The POLO (Partially Omitted Lobe) approach to safely treat in-breast recurrence after intraoperative radiotherapy with electrons.

OBJECTIVES: The aim of this study is to evaluate feasibility of salvage 4-week hypofractionated whole breast radiotherapy (WBRT) in patients with in-breast recurrence after receiving intraoperative radiotherapy with electrons (IOERT) for primary breast cancer (BC). METHODS: BC patients who had repeated quadrantectomy underwent modified WBRT with intensity-modulated radiotherapy using Helical Tomotherapy to underdose the IOERT region. This approach, called POLO (Partially Omitted Lobe), excluded the IOERT volume from receiving the full prescription dose. RESULTS: Nine patients were treated with this approach, receiving 45 Gy in 20 fractions. A simultaneous integrated boost of 2.5 Gy in 20 fractions was delivered in 6/9 patients. Dose constraints and planning objectives were reported. No severe toxicity was reported while local control and overall survival were 100%. CONCLUSION: The POLO approach is technically feasible and capable to achieve a significant reduction of radiation dose delivered to the previous treated IOERT area. ADVANCES IN KNOWLEDGE: The study demonstrates the technical and dosimetric feasibility of conservative salvage whole breast radiotherapy, while sparing the area already treated with IORT, in patients with in-breast recurrence.

Geometric contour variation in clinical target volume of axillary lymph nodes in breast cancer radiotherapy: an AIRO multi-institutional study.

OBJECTIVES: To determine interobserver variability in axillary nodal contouring in breast cancer (BC) radiotherapy (RT) by comparing the clinical target volume of participating single centres (SC-CTV) with a gold-standard CTV (GS-CTV). METHODS: The GS-CTV of three patients (P1, P2, P3) with increasing complexity was created in DICOM format from the median contour of axillary CTVs drawn by BC experts, validated using the simultaneous truth and performance-level estimation and peer-reviewed. GS-CTVs were compared with the correspondent SC-CTVs drawn by radiation oncologists, using validated metrics and a total score (TS) integrating all of them. RESULTS: Eighteen RT centres participated in the study. Comparative analyses revealed that, on average, the SC-CTVs were smaller than GS-CTV for P1 and P2 (by -29.25% and -27.83%, respectively) and larger for P3 (by +12.53%). The mean Jaccard index was greater for P1 and P2 compared to P3, but the overlap extent value was around 0.50 or less. Regarding nodal levels, L4 showed the highest concordance with the GS. In the intra-patient comparison, L2 and L3 achieved lower TS than L4. Nodal levels showed discrepancy with GS, which was not statistically significant for P1, and negligible for P2, while P3 had the worst agreement. DICE similarity coefficient did not exceed the minimum threshold for agreement of 0.70 in all the measurements. CONCLUSIONS: Substantial differences were observed between SC- and GS-CTV, especially for P3 with altered arm setup. L2 and L3 were the most critical levels. The study highlighted these key points to address. ADVANCES IN KNOWLEDGE: The present study compares, by means of validated geometric indexes, manual segmentations of axillary lymph nodes in breast cancer from different observers and different institutions made on radiotherapy planning CT images. Assessing such variability is of paramount importance, as geometric uncertainties might lead to incorrect dosimetry and compromise oncological outcome.

The emerging role of radiation therapists in the contouring of organs at risk in radiotherapy: analysis of inter-observer variability with radiation oncologists for the chest and upper abdomen.

AIMS: To compare the contouring of organs at risk (OAR) between a clinical specialist radiation therapist (CSRT) and radiation oncologists (ROs) with different levels of expertise (senior-SRO, junior-JRO, fellow-FRO). METHODS: On ten planning computed tomography (CT) image sets of patients undergoing breast radiotherapy (RT), the observers independently contoured the contralateral breast, heart, left anterior descending artery (LAD), oesophagus, kidney, liver, spinal cord, stomach and trachea. The CSRT was instructed by the JRO e SRO. The inter-observer variability of contoured volumes was measured using the Dice similarity coefficient (DSC) (threshold of ≥ 0.7 for good concordance) and the centre of mass distance (CMD). The analysis of variance (ANOVA) was performed and a p-value < 0.01 was considered statistically significant. RESULTS: Good overlaps (DSC > 0.7) were obtained for all OARs, except for LAD (DSC = 0.34 ± 0.17, mean ± standard deviation) and oesophagus (DSC = 0.66 ± 0.06, mean ± SD). The mean CMD < 1 cm was achieved for all the OARs, but spinal cord (CMD = 1.22 cm). By pairing the observers, mean DSC > 0.7 and mean CMD < 1 cm were achieved in all cases. The best overlaps were seen for the pairs JRO-CSRT(DSC = 0.82; CMD = 0.49 cm) and SRO-JRO (DSC = 0.80; CMD = 0.51 cm). CONCLUSIONS: Overall, good concordance was found for all the observers. Despite the short training in contouring, CSRT obtained good concordance with his tutor (JRO). Great variability was seen in contouring the LAD, due to its difficult visualization and identification of CT scans without contrast.

Workload of breast image-guided intensity-modulated radiotherapy delivered with TomoTherapy.

OBJECTIVE: To report treatment times (door to door) of adjuvant treatments of breast cancer (BC) with intensity-modulated radiotherapy (IMRT). METHODS: Treatment times of 62 patients with BC on the TomoTherapy Hi-Art System were collected for the analysis. Patients underwent either locoregional radiotherapy (postmastectomy radiotherapy [PMRT]) with helical modality (TomoHelical) or whole breast radiotherapy (RT) with simultaneous integrated boost (WBRT-SIB) with direct modality (TomoDirect). Door-to-door time was broken down into different steps, which were crucial to RT session. RESULTS: A total of 594 treatment fractions were monitored. Median treatment time was 22.4 minutes (17.2-30.8) for PMRT and 14.4 minutes (10.9-23.5) for WBRT-SIB. The mean beam-on time accounted for 61.36% of the overall treatment time for PMRT compared to 57% for WBRT-SIB. The beam-on time was a much more time-consuming process. CONCLUSION: This treatment times analysis on the use of IMRT for BC might be useful to organize and improve the workflow efficiency in RT facilities.

Local Failure After Accelerated Partial Breast Irradiation with Intraoperative Radiotherapy with Electrons: An Insight into Management and Outcome from an Italian Multicentric Study.

BACKGROUND: The aim of this work is to evaluate pattern of care and clinical outcome in a large series of patients with in-breast recurrence (IBR), after quadrantectomy and intraoperative radiation therapy with electrons (IOERT) as partial breast irradiation. PATIENTS AND METHODS: Patients with IBR after IOERT, treated with salvage surgery ± adjuvant reirradiation (re-RT), were selected from a multiinstitution database. Disease-free survival (DFS), overall survival (OS), cumulative incidence of second IBR, and distant metastases (DM) were estimated. RESULTS: A total of 224/267 patients from seven institutions were included. Primary tumors received 21 Gy. Median time to first IBR was 4.3 years (range 2.6-6.1 years). Salvage mastectomy and repeat quadrantectomy were performed in 135 (60.3%) and 89 (39.7%) patients, followed by adjuvant re-RT in 21/135 (15.5%) and 63/89 (70.8%), respectively. Median follow-up after salvage treatment was 4.1 years. Overall, 5- and 8-year outcomes were as follows: cumulative incidence of second IBR: 8.4% and 14.8%; cumulative incidence of DM: 17.1% and 22.5%; DFS: 67.4% and 52.5%; OS: 89.3% and 74.7%. The risk of second IBR was similar in the salvage mastectomy and repeat quadrantectomy + RT groups [hazard ratio (HR) 1.41, p = 0.566], while salvage mastectomy patients had greater risk of DM (HR 3.15, p = 0.019), as well as poorer DFS (HR 2.13, p = 0.016) and a trend towards worse OS (HR 3.27, p = 0.059). Patients who underwent repeat quadrantectomy alone had worse outcomes (second IBR, HR 5.63, p = 0.006; DFS, HR 3.21, p = 0.003; OS, HR 4.38, p = 0.044) than those adding re-RT. CONCLUSIONS: Repeat quadrantectomy + RT represents an effective salvage approach and achieved local control comparable to that of salvage mastectomy.

HALFMOON TomoTherapy (Helical ALtered Fractionation for iMplant partial OmissiON): implant-sparing post-mastectomy radiotherapy reshaping the clinical target volume in the reconstructed breast.

PURPOSE: To report the dosimetric feasibility of the radiation technique HALFMOON (Helical ALtered Fractionation for iMplant partial OmissiON) for post-mastectomy radiation therapy (PMRT) in intermediate-high-risk breast cancer patients with implant-based immediate breast reconstruction, where the clinical target volume (CTV) does not include the whole implant (implant-sparing approach). METHODS: In the HALFMOON technique, the CTV consisted of skin, subcutaneous tissues, and pectoralis major muscle, excluding the implant, chest wall muscles, and rib plane. The HALFMOON plans were compared with conventionally contoured CTV plans, in which the whole implant, chest wall muscles, and ribs plane were included in the CTV, in a ratio 1:3. All patients underwent hypofractionated treatment of 40.05 Gy/15 fractions, using helical Tomotherapy®. RESULTS: Eighteen patients undergoing HALFMOON technique were compared to 54 subjects treated with conventionally contoured CTV plans. No difference was found in the planning target volume coverage between the two groups. Conversely, a statistically relevant dose reduction in HALFMOON patients was observed for ipsilateral lung (D15%, p < 0.0001; D20%, p < 0.0001; D35%, p = 0.003), contralateral lung (D20%, p = 0.048), contralateral breast (D15%, p = 0.031; D20%, p = 0.047), and stomach (Dmean, p = 0.011). Regarding the implant, V90% and D50% decreased by 46% and 8%, respectively, in the HALFMOON plans (p < 0.0001). CONCLUSION: The HALFMOON approach is technically feasible and resulted in high-dose conformity of the target with a significant reduction of radiation dose delivered to implant and other organs. A clinical study is needed to assess the impact on reconstruction cosmetic outcome and local control.

Ductal carcinoma in situ and intraoperative partial breast irradiation: Who are the best candidates? Long-term outcome of a single institution series.

AIMS: To report the long-term outcome of a single institution series of pure ductal carcinoma in situ (DCIS) treated with accelerated partial irradiation using intraoperative electrons (IOERT). METHODS: From 2000 to 2010, 180 DCIS patients, treated with quadrantectomy and 21 Gy IOERT, were analyzed in terms of ipsilateral breast recurrences (IBRs) and survival outcomes by stratification in two subgroups. The low-risk group included patients who fulfilled the suitable definition according to American Society of Radiation Oncology (ASTRO) Guidelines (size ≤2.5 cm, grade 1-2 and surgical margins ≥3 mm) (Suitable), while the remaining ones formed the high-risk group (Non-Suitable). RESULTS: Eighty-four and 96 patients formed the Suitable and Non-Suitable groups, respectively. In the whole population, the cumulative incidence of IBR at 5, 7 and 10 years was 19%, 21%, and 25%, respectively. In the Suitable group, the cumulative incidence of IBR remained constant at 11% throughout the years, while in the Non-Suitable group increased from 26% at 5 years to 36% at 10 years (p < 0.0001). When hormonal positivity and HER2 absence of expression were added to the selection of the Suitable group, the cumulative incidence of IBR dropped and stabilized at 4% at 10 years. None died of breast cancer. In the whole population, 5-year and 10-year overall survival rate was 98% and 96.5%, respectively, without any difference between the two groups. CONCLUSIONS: The overall and by group IBR rates were high and stricter criteria are required for acceptable local control for Suitable DCIS. Because of the concerns raised, IOERT should not be used in clinical practice.