Prone breast intensity modulated radiation therapy: 5-year results

Noninferiority of Local Control and Comparable Toxicity of Intensity Modulated Radiation Therapy With Simultaneous Integrated Boost in Breast Cancer: 5-Year Results of the IMRT-MC2 Phase III Trial

PURPOSE

The IMRT-MC2 trial was conducted to demonstrate the noninferiority of conventionally fractionated intensity modulated radiation therapy with a simultaneous integrated boost to 3-dimensional conformal radiation therapy with a sequential boost for adjuvant breast radiation therapy.

METHODS AND MATERIALS

A total of 502 patients were randomized between 2011 and 2015 for the prospective, multicenter, phase III trial (NCT01322854). Five-year results of late toxicity (late effects normal tissue task force-subjective, objective, management, and analytical), overall survival, disease-free survival, distant disease-free survival, cosmesis (Harvard scale), and local control (noninferiority margin at hazard ratio [HR] of 3.5) were analyzed after a median follow-up of 62 months.

RESULTS

The 5-year local control rate for the intensity modulated radiation therapy with simultaneous integrated boost arm was non-inferior to the control arm (98.7% vs 98.3%, respectively; HR, 0.582; 95% CI, 0.119-2.375; P = .4595). Furthermore, there was no significant difference in overall survival (97.1% vs 98.3%, respectively; HR, 1.235; 95% CI, 0.472-3.413; P = .6697), disease-free survival (95.8% vs 96.1%, respectively; HR, 1.130; 95% CI, 0.487-2.679; P = .7758), and distant disease-free survival (97.0% vs 97.8%, respectively; HR, 1.667; 95% CI, 0.575-5.434; P = .3601). After 5 years, late toxicity evaluation and cosmetic assessment further showed no significant differences between treatment arms.

CONCLUSIONS

The 5-year results of the IMRT-MC2 trial provide strong evidence that the application of conventionally fractionated simultaneous integrated boost irradiation for patients with breast cancer is both safe and effective, with noninferior local control compared with 3-dimensional conformal radiation therapy with sequential boost.

Comparison of prone and supine positioning for breast cancer radiotherapy using REQUITE data: dosimetry, acute and two years physician and patient-reported outcomes

OBJECTIVE

Most patients receive whole breast radiotherapy in a supine position. However, two randomised trials showed lower acute toxicity in prone position. Furthermore, in most patients, prone positioning reduced doses to the organs at risk. To confirm these findings, we compared toxicity outcomes, photographic assessment, and dosimetry between both positions using REQUITE data.

METHODS

REQUITE is an international multi-centre prospective observational study that recruited 2069 breast cancer patients receiving radiotherapy. Data on toxicity, health-related quality of life (HRQoL), and dosimetry were collected, as well as a photographic assessment. A matched case control analysis compared patients treated prone (n = 268) versus supine (n = 493). Exact matching was performed for the use of intensity-modulated radiotherapy, boost, lymph node irradiation, chemotherapy and fractionation, and the nearest neighbour for breast volume. Primary endpoints were dermatitis at the end of radiotherapy, and atrophy and cosmetic outcome by photographic assessment at two years.

RESULTS

At the last treatment fraction, there was no significant difference in dermatitis (p = .28) or any HRQoL domain, but prone positioning increased the risk of breast oedema (p < .001). At 2 years, patients treated in prone position had less atrophy (p = .01), and higher body image (p < .001), and social functioning (p < .001) scores. The photographic assessment showed no difference in cosmesis at 2 years (p = .22). In prone position, mean heart dose (MHD) was significantly lower for left-sided patients (1.29 Gy vs 2.10 Gy, p < .001) and ipsilateral mean lung dose (MLD) was significantly lower for all patients (2.77 Gy vs 5.89 Gy, p < .001).

CONCLUSIONS

Prone radiotherapy showed lower MLD and MHD compared to supine position, although the risk of developing breast oedema during radiotherapy was higher. At 2 years the photographic assessment showed no difference in the cosmetic outcome, but less atrophy was seen in prone-treated patients and this seems to have a positive influence on the HRQoL domain of body image.

The role of the radiation therapy breast boost in the 2020s

Given that most local relapses of breast cancer occur proximal to the original location of the primary, the delivery of additional radiation dose to breast tissue that contained the original primary cancer (known as a "boost") has been a standard of care for some decades. In the context of falling relapse rates, however, it is an appropriate time to re-evaluate the role of the boost. This article reviews the evolution of the radiotherapy boost in breast cancer, discussing who to boost and how to boost in the 2020s, and arguing that, in both cases, less is more.

Hypofractionation with simultaneous integrated boost after breast-conserving surgery: Long term results of two phase-II trials

Purpose

Methods

Results

Conclusion

•

Hypofractionated breast radiotherapy with SIB was safe and feasible.

•

The local control rate at 5 years was 99.6%.

•

The rate of late grade 3 toxicity was 0.7%.

A novel carbon-fibre adjustable reusable accessory (CARA) for supine breast positioning to reduce toxicity in breast adjuvant radiotherapy: a study protocol for a multicentre phase III randomized controlled trial

Background

A novel device for supine positioning in breast radiotherapy for patients with large or pendulous breasts has been developed and tested in phase II studies. This trial is designed to assess the efficacy of the device to reduce skin toxicity and unwanted normal tissue dose in comparison to the current clinical standard for supine breast support during breast radiotherapy.

Methods

Patients at high risk for moist desquamation, having infra-mammary fold or lateral ptosis, will be randomized into two arms. Patients in the control arm will receive breast radiotherapy with supine positioning using current standard of care. Patients in the experimental arm will be positioned supine with the novel device. The primary endpoint is the incidence of moist desquamation in the infra-mammary fold. We hypothesize a 20% reduction (from 50 to 30%) in the rate of moist desquamation in the study arm versus the control arm. For 80% power, two-tailed α = 0.05 and 10% loss to follow up, 110 patients will be assigned to each arm. The proportion of patients experiencing moist desquamation in the two arms will be compared using logistic regression adjusting for brassiere cup size, skin fold size, body mass index, smoking status, and dose fractionation schedule. An unadjusted comparison will also be made using the chi-square test, or Fisher’s exact test, if appropriate. Secondary endpoints include dose-volume statistics for the lung and heart, skin dose and clinical parameters including setup time, reproducibility, and staff experience with setup procedures. Patient-reported pain, skin condition interference with sleep and daily activities, and comfort during treatment are also secondary endpoints.

Discussion

Based on results from earlier phase II studies, it is expected that the device-enabled elimination of infra-mammary fold should reduce toxicity and improve quality of life for this patient population. Earlier studies showed reduction in dose to organs at risk including lung and heart, indicating potential for other long-term benefits for patients using the device. This study is limited to acute skin toxicity, patient-reported outcomes, and clinical factors to inform integration of the device into standard breast radiotherapy procedures.

Trial registration

Clinicaltrials.gov identifier: NCT04257396. Registered February 6 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09759-y.

Prone versus supine free-breathing for right-sided whole breast radiotherapy

Prone setup has been advocated to improve organ sparing in whole breast radiotherapy without impairing breast coverage. We evaluate the dosimetric advantage of prone setup for the right breast and look for predictors of the gain. Right breast cancer patients treated in 2010–2013 who had a dual supine and prone planning were retrospectively identified. A penalty score was computed from the mean absolute dose deviation to heart, lungs, breasts, and tumor bed for each patient's supine and prone plan. Dosimetric advantage of prone was assessed by the reduction of penalty score from supine to prone. The effect of patients' characteristics on the reduction of penalty was analyzed using robust linear regression. A total of 146 patients with right breast dual plans were identified. Prone compared to supine reduced the penalty score in 119 patients (81.5%). Lung doses were reduced by 70.8%, from 4.8 Gy supine to 1.4 Gy prone. Among patient's characteristics, the only significant predictors were the breast volumes, but no cutoff could identify when prone would be less advantageous than supine. Prone was associated with a dosimetric advantage in most patients. It sets a benchmark of achievable lung dose reduction.

Trial registration: ClinicalTrials.gov NCT02237469, HUGProne, September 11, 2014, retrospectively registered.

Hypofractionated Simultaneous Integrated Boost Radiotherapy Versus Conventional Fractionation Radiotherapy of Early Breast Cancer After Breast-Conserving Surgery: Clinical Observation and Analysis

Purpose: The objective of this retrospective study is to evaluate the efficacy and safety of hypofractionated simultaneous integrated boost radiotherapy for early breast cancer patients undergoing breast-conserving surgery. Methods: A total of 185 women with early breast cancer undergoing breast-conserving surgery were retrospectively divided into hypofractionated simultaneous integrated boost group and conventional fractionation group. Hypofractionated simultaneous integrated boost included 104 patients and the dose of whole-breast radiation reached 42.56 Gy in 16 fractions and simultaneously tumor bed boost to 48 Gy in 16 fractions, which course of radiotherapy was 22 days. The 81 patients of the conventional fractionation group received whole breast radiation to 50 Gy in 25 fractions and followed by tumor bed boost to 10 Gy in 5 fractions, which course of radiotherapy was 40 days. Clinical information including patients' characteristics, skin toxicity, myelosuppression, radiation pneumonia, and cosmetic effects was recorded to analyze the influence of age, chemotherapy, position, and breast volume on the results of radiotherapy. Results: Hypofractionated simultaneous integrated boost group had no case of recurrence after a median follow-up of 25.6 months (9-47 months)) as compared with 2 after a median follow-up of 33.4 months (25-45 months) in the conventional fractionation group. The 2 groups had similar results in skin toxicity, cosmetic outcomes, and radiation pneumonia. In terms of myelosuppression, grade 1, grade 2, and grade 3 of myelosuppression in the hypofractionated simultaneous integrated boost group accounted for 16.7%, 12.3%, and 3.5% as compared with 30.0%, 21.1%, and 12.3% of the conventional fractionation group, respectively (P = .000). Conclusions: HF-SIB RT is a considerable option in patients after breast-conserving surgery with a lower degree of myelosuppression and shorter treatment time.

Long term results of a phase II trial of hypofractionated adjuvant radiotherapy for early-stage breast cancer with volumetric modulated arc therapy and simultaneous integrated boost

PURPOSE

to report toxicity and cosmetic outcome with a median follow-up of 6 years of a phase II trial of hypofractionated radiotherapy with volumetric modulated arc therapy (VMAT) and simultaneous integrated boost (SIB) for early-stage breast cancer after conservative surgery.

MATERIALS AND METHODS

From August 2010 to September 2014, patients requiring adjuvant radiotherapy for early-stage breast cancer were treated according to a phase I-II protocol with SIB to 40.5 and 48 Gy to the breast and the boost region, respectively, with VMAT technique. The primary endpoint evaluated the treatment feasibility regarding adherence to required dose constraints for target, heart and lungs. Acute and late toxicity, local and distant control were secondary endpoints.

RESULTS

450 patients were included in the trial and analysed after a median follow-up of 6 years. Acute toxicity was already presented in a previous paper. Regarding late toxicity, 93% of patients had no skin alteration at five years, while 5.3% and 1.3% did record G1 and G2 residual toxicity, respectively. Cosmetic outcome was scored good or excellent in almost all cases (97.2%), fair only in 2.3% of patients. Residual tenderness in the irradiated breast was reported by 10% of patients. Cosmesis and breast pain improved during follow-up. Two cases of G2 pneumonitis and two cases of ischemic cardiopathy were registered during follow-up. Five cases presented local recurrence in the homolateral breast, four patients had a new primary cancer in the contralateral breast, while distant metastasis developed in 7 patients.

CONCLUSION

After more than six years, hypofractionated VMAT with SIB for adjuvant radiotherapy in early-stage breast cancer patients remains a safe and effective approach. Mature data on skin toxicity and cosmetic outcome are encouraging. However, longer follow-up is required to evaluate local control, cardiac toxicity and secondary carcinogenesis.

A comparative study on hypofractionated whole-breast irradiation with sequential or simultaneous integrated boost on different positions after breast-conserving surgery

This study explored the dosimetric difference between hypofractionated whole-breast irradiation (HFWBI) with sequential boost (SEB) and simultaneous integrated boost (SIB) based on supine and prone positions to identify the superior boost mode and superior position. Thirty breast cancer patients eligible for HFWBI after breast-conserving surgery were enrolled. All patients underwent 3DCT simulation scanning in both supine and prone positions. For the SEB-HFWBI plan, the dose prescribed for the planning target volume (PTV) of whole breast (WB) was 2.67 Gy per fraction with a total of 15 fractions, followed by a sequential boost of 3.2 Gy per fraction to the PTV of tumor bed (TB) in 3 fractions. For the SIB-HFWBI plan, the dose prescribed for the PTV of WB was 2.67 Gy per fraction with a total of 15 fractions, with a simultaneously integrated boost of 3.2 Gy per fraction to the PTV of TB with a total of 15 fractions. Regardless of the position, for the PTV of TB, the conformal index (CI) in the SIB-HFWBI plans was greater than those in the SEB-HFWBI plans (T = − 8.114, − 8.114; both P < 0.05). The CI for the PTV of WB increased significantly in the prone position relative to the supine position in both two plans(Z = − 3.340, − 3.501; all P < 0.05). The study suggested that prone SIB-HFWBI might be more suitable for postoperative radiotherapy after breast-conserving surgery for early-stage breast cancer patients.

Reduction in Doses to Organs at Risk and Normal Tissue During Breast Radiation Therapy With a Carbon-Fiber Adjustable Reusable Accessory

PURPOSE

This pilot study (ClinicalTrials.gov NCT04543851) investigates a novel breast positioning device using a low density, high tensile carbon-fiber cradle to support the breast, remove the inframammary fold, and reduce dose to organs at risk for whole breast radiation therapy in the supine position.

METHODS AND MATERIALS

Thirty patients with inframammary folds ≥1 cm or lateral ptosis in supine treatment position were planned with standard positioning and with a carbon-fiber Adjustable Reusable Accessory (CARA) breast support. Twenty patients received whole breast with or without regional nodal irradiation with 42.5 Gy in 16 fractions or 50 Gy in 25 fractions using CARA. Median body mass index was 32 in this study.

RESULTS

CARA removed all inframammary folds and reduced V20Gy_{ipsilateral lung,} V105%_breast, and V50% _body, without compromising target coverage. Median (range) V20Gy_{ipsilateral lung} for whole breast radiation therapy was 12.3% (1.4%-28.7%) with standard of care versus 10.9% (1.2%-17.3%) with CARA (Wilcoxon P = .005). Median V105% _breast was 8.0% (0.0%-29%) with standard of care versus 4.0% (0.0%-23%) with CARA (P = .006) and median V50% _body was 3056 mL (1476-5285 mL) versus 2780 mL (1415-5123 mL) with CARA (P = .001). CARA was compatible with deep inspiration breath hold and achieved median V25Gy_heart = 0.1% (range 0%-1.9%) for all patients with left breast cancer. Skin reactions with CARA were consistent with historical data and daily variation in treatment setup was consistent with standard supine positioning.

CONCLUSIONS

CARA can reduce V105%_breast, lung and normal tissue dose, and remove the inframammary fold for breast patients with large or pendulous breasts and high body mass index treated in the supine position, without compromising target coverage. CARA will undergo further study in a randomized controlled trial.

Prone Positioning With Deep Inspiration Breath Hold for Left Breast Radiotherapy

BACKGROUND

With advances in treatment, outcomes for early-stage breast cancer are improving. We investigated the combination of prone position and deep inspiration breath hold to decrease cardiac doses for left-sided breast radiotherapy.

MATERIAL AND METHODS

Fifteen patients with left-sided breast cancer were enrolled on a single-institution prospective study. Each patient underwent 2 prone positioned computed tomography simulation scans utilizing free breathing and breath-hold. Separate treatment plans for each computed tomography simulation scan were created using tangential fields, and heart and left lung doses were compared between free breathing and breath-hold plans. The technique with the lower mean dose for the heart was used for treatment. All patients were treated with a hypofractionated regimen of 40 to 42 Gy in 15 to 16 fractions, followed by a lumpectomy cavity boost of 10 Gy in 5 fractions when indicated. Wilcoxon paired signed rank tests and paired t tests were performed for statistical analysis of dosimetric endpoints.

RESULTS

The median age of our patients was 58 years (range, 40-72 years). One patient was not able to tolerate prone positioning at simulation, leaving 14 patients with evaluable paired scans. The average mean heart dose with free breathing and with breath-hold was 0.93 Gy and 0.72 Gy, respectively (P = .0063). The average max heart dose with free breathing and with breath-hold was 15.70 Gy and 7.19 Gy, respectively (P = .001). The average mean left lung dose with free breathing and with breath-hold was 0.65 Gy and 0.88 Gy, respectively (P = .011).

CONCLUSIONS

Our results indicate that breath-hold using the real-time position management system may provide additional cardiac dose reduction in patients receiving prone left-breast radiotherapy treated with tangential fields.

Intensity-Modulated Radiotherapy with Concomitant Boost After Breast Conserving Surgery: A Phase I-II Trial

Purpose

A concomitant boost (CB) in patients treated with postoperative radiotherapy after conservative surgery of invasive breast cancer (BC) has been suggested for treatment time reduction and therapy intensification. The aim of this analysis was to assess long-term tolerability of a CB in patients treated with postoperative intensity Modulated Accelerated RAdiotherapy (MARA).

Patients and Methods

In this phase I–II trial, 321 patients with intermediate-high risk BC (pT1-4 with at least one of the following characteristics: pre or perimenopausal status, pN2-3, positive or close margins) were enrolled. Patients were treated with forward-planned intensity modulated radiotherapy (IMRT) and CB. A total dose of 50 Gy (2 Gy/fraction) and 60 Gy (2.4 Gy/fraction) was prescribed to the whole breast and the tumor bed, respectively. The potential impact of hypertension, diabetes, smoking habit, alcohol consumption, chemotherapy, and hormone therapy on both skin and subcutaneous late toxicity-free survival (LTFS) was evaluated. Survival curves were calculated using the Kaplan–Meier method.

Results

Median follow-up was 52 months (range: 3–115). Regional node irradiation, adjuvant chemotherapy and hormonal therapy were prescribed to 29.3%, 65.4% and 81.0% of patients, respectively. Five-year G2 and G3 skin LTFS were 95.6% and 100.0%, respectively. Five-year G2 and G3 subcutaneous LTFS were 80.0% and 98.6%, respectively. Only diabetes showed a significant correlation with worse G3 subcutaneous LTFS (p: 0.024). Five-year loco-regional control, metastasis-free survival, disease-free survival, and overall survival were 98.0%, 91.8%, 89.7% and 96.3%, respectively.

Conclusion

IMRT combined with CB was associated with a low risk of > G2 late toxicities (0.0% and 1.4% for skin and subcutaneous tissue, respectively). The cumulative actuarial incidence of local recurrences was 2.0% despite the exclusion of low-risk patients. Our results suggest that CB is safe and effective in patients with intermediate-high risk BC.

Trial Registration

ClinicalTrials.gov: NCT03471741.

Long-term patient-rated cosmetic and satisfactory outcomes of early breast cancer treated with conventional versus hypofractionated breast irradiation with simultaneous integrated boost technique

To compare patient-rated cosmetic and satisfactory outcomes between conventional fractionation with simultaneously integrated boost (C-SIB) vs hypofractionation with SIB (H-SIB) in early breast cancer. Patients with stage I and II breast cancer who received breast-conserving surgery followed by radiation with SIB to tumor bed and completed questionnaire were included in this study. Radiotherapy was as follows: C-SIB arm = 50 Gy and 65 Gy in 25 fractions and H-SIB arm = 43.2 Gy and 52.8 Gy in 16 fractions to the whole breast and tumor bed, respectively. Single cross-sectional assessment of the breast cosmesis was done by patients and radiation oncologist at a follow-up visit. Breast cosmetic and satisfaction scores were collected using a four-point Harvard/NSABP/RTOG cosmesis criteria scale and a four-point Likert-type scale, respectively. Of a total of 114 patients (C-SIB = 57) and (H-SIB = 57) arms, a median time from radiotherapy completion to questionnaire response was 7.2 years. Patient-rated cosmetic outcome in C-SIB vs H-SIB was "excellent" in 40.3% vs 45.6%, "good" in 33.3% vs 42.1%, "fair" in 21.1% vs 10.5%, and "poor" in 5.3% vs 1.8% (P = .288). Corresponding satisfaction was "very satisfied" in 52.6% vs 57.9%, "satisfied" in 40.4% vs 35.1%, "neutral" in 7.0% vs 5.2%, and "unsatisfied" in 0% vs 1.8% (P = .683). Stage I and older age at radiotherapy were predictors for favorable (good or excellent) cosmesis and satisfaction, respectively. In early-stage breast cancer, H-SIB provided a trend for better cosmesis than C-SIB while maintaining satisfaction. The reduction in treatment duration and cost as well as favorable cosmesis outcomes encourages the use of H-SIB.

Long-term outcomes of patients with conserved breast cancer treated with adjuvant hypofractionated prone breast intensity-modulated radiation therapy

INTRODUCTION

New techniques for adjuvant radiation therapy after breast conservation include prone positioning, hypofractionation and intensity-modulated radiation therapy (IMRT). Long-term evaluations of this combination are lacking, and we report our own experience.

METHODS

Patients with invasive breast cancer followed for a minimum 36 months post-IMRT were eligible. Dose used was 40 Gray in 15 fractions over 3 weeks to the whole breast via forward-planned prone, whole breast IMRT. A 10 Gy in 5 fraction supine boost was offered.

RESULTS

Between January 2012 and January 2020, 2199 patients had breast conservation and adjuvant radiation: 489 received hypofractionated prone breast IMRT, with 155 eligible for our evaluation. Median follow-up was 52 months. Median age was 62 (range 36-80), 78.7% were T1, 20.6% were T2, and 12.3% were node-positive. Grade was 1 in 26.5%, 2 in 43.9% and 3 in 29.7%; 87.1% were oestrogen receptor positive, 3.2% were HER2 positive, and 11.0% were triple negative. 58.6% received a boost, 74.8% endocrine therapy and 32.3% chemotherapy. No patient developed local recurrence. One regional recurrence was successfully salvaged. Six patients (3.9%) developed metastases, and 1.9% died. Five-year actuarial local recurrence-free, regional recurrence-free and breast cancer-specific survival rates were 100.0%, 98.2% and 94.8%. Late grade 1 and 2 breast pain occurred in 20.0% and 1.3% of patients. Only 11.0% had new pain compared to pre-radiation. No patient developed radiation-induced pneumonitis, pulmonary fibrosis, rib fracture or cardiac toxicity. All patients scored cosmesis as 'good' or better.

CONCLUSION

Adjuvant hypofractionated prone breast IMRT has excellent locoregional control and minimal toxicity.

Characterization of Respiration-Induced Motion in Prone Versus Supine Patient Positioning for Thoracic Radiation Therapy

Purpose

Variations in the breathing characteristics, both on short term (intrafraction) and long term (interfraction) time scales, may adversely affect the radiation therapy process at all stages when treating lung tumors. Prone position has been shown to improve consistency (ie, reduced intrafraction variability) and reproducibility (ie, reduced interfraction variability) of the respiratory pattern with respect to breathing amplitude and period as a result of natural abdominal compression, with no active involvement required from the patient. The next natural step in investigating breathing-induced changes is to evaluate motion amplitude changes between prone and supine targets or organs at risk, which is the purpose of the present study.

Methods and Materials

Patients with lung cancer received repeat helical 4-dimensional computed tomography scans, one prone and one supine, during the same radiation therapy simulation session. In the maximum-inhale and maximum-exhale phases, all thoracic structures were delineated by an expert radiation oncologist. Geometric centroid trajectories of delineated structures were compared between patient orientations. Motion amplitude was measured as the magnitude of difference in structure centroid position between inhale and exhale.

Results

Amplitude of organ motion was larger when the patient was in the prone position compared with supine for all structures except the lower left lobe and left lung as a whole. Across all 12 patients, significant differences in mean motion amplitude between orientations were identified for the right lung (3.0 mm, P = .01), T2 (0.5 mm, P = .01) and T12 (2.1 mm, P < .001) vertebrae, the middle third of the esophagus (4.0 mm, P = .03), and the lung tumor (1.7 mm, P = .02).

Conclusions

Respiration-induced thoracic organ motion was quantified in the prone position and compared with that of the supine position for 12 patients with thoracic lesions. The prone position induced larger organ motion compared with supine, particularly for the lung tumor, likely requiring increases in planning margins compared with supine.

A Prospective Trial to Compare Deep Inspiratory Breath Hold With Prone Breast Irradiation

PURPOSE

To compare heart and lung doses for adjuvant whole breast irradiation (WBI) between radiation plans generated supine with deep inspiratory breath hold (S-DIBH) and prone with free-breathing (P-FB) and examine the effect of breast volume (BV) on dosimetric parameters.

METHODS AND MATERIALS

Patients with left breast ductal carcinoma in situ or invasive cancer receiving adjuvant WBI were enrolled on a single-institutional prospective protocol. Patients were simulated S-DIBH and P-FB; plans were generated using both scans. Wilcoxon signed-rank and rank-sum tests were used to compare intrapatient differences between plans for the entire cohort and within BV groups defined by tertiles.

RESULTS

Forty patients were enrolled. Thirty-four patients are included in the analysis owing to patient withdrawal or inability to hold breath. With WBI dose of 4005 to 4256 cGy, mean heart dose (MHD) was 80 cGy in S-DIBH and 77 cGy in P-FB (P = .08). Mean ipsilateral lung dose (MLD) was 453 cGy in S-DIBH and 45 cGy in P-FB (P < .0001). Mean and max left anterior descending artery doses were 251 cGy and 551 cGy in S-DIBH, respectively (P = .1), and 324 cGy and 993 cGy in P-FB, respectively (P = .3). Hot spot and separation were 109% and 22 cm in S-DIBH, respectively, and 107% and 16 cm in P-FB, respectively (P < .0001). For patients with smallest BV, S-DIBH improved MHD and left anterior descending artery doses; for those with largest BV, P-FB improved cardiac dosimetry. With increasing BV, there was an increasing advantage of P-FB for MHD (P = .05), and max (P = .03) and mean (P = .02) left anterior descending artery doses, and the reduction in MLD, hot spot, and separation with P-FB increased (P < .05).

CONCLUSIONS

MHD did not differ between P-FB and S-DIBH, whereas MLD was significantly lower with P-FB. Analysis according to breast volume revealed improved cardiac dosimetry with S-DIBH for women with smallest BV and improved cardiac dosimetry with P-FB for women with larger BV, thereby providing a dosimetric rationale for using breast size to help determine the optimal positioning for WBI.

Dosimetric evaluation and systematic review of radiation therapy techniques for early stage node-negative breast cancer treatment

Radiation therapy (RT) is essential in treating women with early stage breast cancer. Early stage node-negative breast cancer (ESNNBC) offers a good prognosis; hence, late effects of breast RT becomes increasingly important. Recent literature suggests a potential for an increase in cardiac and pulmonary events after RT. However, these studies have not taken into account the impact of newer and current RT techniques that are now available. Hence, this review aimed to evaluate the clinical evidence for each technique and determine the optimal radiation technique for ESNNBC treatment. Currently, six RT techniques are consistently used and studied: 1) prone positioning, 2) proton beam RT, 3) intensity-modulated RT, 4) breath-hold, 5) partial breast irradiation, and 6) intraoperative RT. These techniques show dosimetric promise. However, limited data on late cardiac and pulmonary events exist due to challenges in long-term follow-up. Moving forward, future studies are needed to validate the efficacy and clinical outcomes of these current techniques.

Hypofractionation with simultaneous boost in breast cancer patients receiving adjuvant chemotherapy: A prospective evaluation of a case series and review of the literature

INTRODUCTION

To evaluate acute toxicity and cosmetic outcomes of hypofractionated simultaneous integrated boost (SIB) as adjuvant treatment after breast-conserving surgery and adjuvant chemotherapy and to review the association of chemotherapy and short fractionation with boost.

MATERIALS AND METHODS

Patients presenting early-stage breast cancer were enrolled in a phase II trial. All patients received VMAT-SIB technique to the whole breast and tumor bed in 15 fractions, for a total dose of 40.5 and 48 Gy. Acute and late skin toxicities and breast pain were recorded. Cosmetic outcomes were also assessed as excellent/good or fair/poor.

RESULTS

Between August 2010 and December 2015, 787 consecutive patients were treated and had at least 2 year follow-up. A subset of 175 patients underwent adjuvant chemotherapy (median age of 55 years) and was analysed. The median follow up was 39 months (range 24-80). At the end of RT treatment, skin toxicity was G1 in 51.1% of patients, G2 in 9.7%. At 2 years of follow up, it was G1 in 13.5% of patients, no cases ≥ G2; cosmetic outcome was excellent in 63.5% and good in 36.5% of the patients. No significant difference compared to the patients without systemic therapy was observed.

CONCLUSION

Hypofractionated VMAT-SIB in patients who had undergone adjuvant systemic therapy was safe and well tolerated in terms of acute and early late settings and cosmesis. Our data confirmed the results of other studies published on the association of hypofractionation and chemotherapy or concomitant boost.

Breast size impact on adjuvant radiotherapy adverse effects and dose parameters in treatment planning

Background Breast radiotherapy is an established adjuvant treatment after breast conserving surgery. One of the important individual factors affecting the final cosmetic outcome after radiation is breast size. The purpose of this review is to summarise the clinical toxicity profile of adjuvant radiotherapy in women with breasts of various sizes, and to evaluate the treatment planning studies comparing target coverage and dose to thoracic organs at risk in relation to breast size. Conclusions Inhomogeneity and excessive radiation dose (hot spots) in the planning of target volume as well as large volume of the breast per se, all contribute to a higher rate of acute adverse events and suboptimal final cosmetic outcome in adjuvant breast cancer radiotherapy, regardless of the fractionation schedule. Improved homogeneity leads to a lower rate of ≥ grade 2 toxicity and can be achieved with three-dimensional conformal or modulated radiotherapy techniques. There may be an association between body habitus (higher body mass index, bigger breast size, pendulous breast, and large chest wall separation) and a higher mean dose to the ipsilateral lung and whole heart. A combination of the technical innovations (i.e. the breath-hold technique, prone position with or without holding breath, lateral decubitus position, and thermoplastic bra), dose prescription (i.e. moderate hypofractionation), and irradiated volume (i.e. partial breast irradiation) should be tailored to every single patient in clinical practice to mitigate the risk of radiation adverse effects.

Late complications of radiation therapy for breast cancer: evolution in techniques and risk over time

Radiation therapy in combination with surgery, chemotherapy, and endocrine therapy as indicated, has led to excellent local and distant control of early stage breast cancers. With the majority of these patients surviving long term, mitigating the probability and severity of late toxicities is vital. Radiation to the breast, with or without additional fields for nodal coverage, has the potential to negatively impact long term cosmetic outcome of the treated breast as well as cause rare, but severe, complications due to incidental dosage to the heart, lungs and contralateral breast. The long-term clinical side-effects of breast radiation have been studied extensively. This review aims to discuss the risk of developing late complications following breast radiation and how modern techniques can be used to diminish these risks.

Evaluation of target dose inhomogeneity in breast cancer treatment due to tissue elemental differences

BACKGROUND

Monte Carlo simulations were run to estimate the dose variations generated by thedifference arising from the chemical composition of the tissues.

METHODS

CT datasets of five breast cancer patients were selected. Mammary gland was delineated as clinical target volume CTV, as well as CTV_lob and CTV_fat, being the lobular and fat fractions of the entire mammary gland. Patients were planned for volumetric modulated arc therapy technique, optimized in the Varian Eclipse treatment planning system. CT, structures and plans were imported in PRIMO, based on Monte Carlo code Penelope, to run three simulations: AdiMus, where the adipose and muscle tissues were automatically assigned to fat and lobular fractions of the breast; Adi and Mus, where adipose and muscle, respectively were assigned to the whole mammary gland. The specific tissue density was kept identical from the CT dataset. Differences in mean doses in the CTV_lob and CTV_fat structures were evaluated for the different tissue assignments. Differences generated by the tissue composition and estimated by Acuros dose calculations in Eclipse were also analysed.

RESULTS

From Monte Carlo simulations, the dose in the lobular fraction of the breast, when adipose tissue is assigned in place of muscle, is overestimated by 1.25 ± 0.45%; the dose in the fat fraction of the breast with muscle tissue assignment is underestimated by 1.14 ± 0.51%. Acuros showed an overestimation of 0.98 ± 0.06% and an underestimation of 0.21 ± 0.14% in the lobular and fat portions, respectively. Reason of this dissimilarity resides in the fact that the two calculations, Monte Carlo and Acuros, differently manage the range of CT numbers and the material assignments, having Acuros an overlapping range, where two tissues are both present in defined proportions.

CONCLUSION

Although not clinically significant, the dose deposition difference in the lobular and connective fat fraction of the breast tissue lead to an improved knowledge of the possible dose distribution and homogeneity in the breast radiation treatment.

Hypofractionated Whole-Breast Irradiation in Women Less Than 50 Years Old Treated on 4 Prospective Protocols

PURPOSE

Hypofractionated whole-breast radiation therapy (RT) has proved to be equivalent to conventionally fractionated RT in multiple randomized trials. There is controversy regarding its use in younger women because of their underrepresentation in trials and the concern for late toxicity. We evaluated disease control and cosmetic outcomes in patients aged <50 years treated with hypofractionated RT in 4 prospective single-institutional trials.

METHODS AND MATERIALS

From 2003 to 2015, 1313 patients were enrolled in 4 prospective protocols investigating the use of adjuvant hypofractionated RT after breast-conserving surgery with a daily or weekly concomitant boost. We identified the records of 348 patients aged <50 years at consultation for this analysis. Overall survival, disease-free survival, and local recurrence-free survival were estimated using the Kaplan-Meier method by study and across studies using meta-analytic methods. The late effects of RT, clinician-rated cosmesis, and patient-rated cosmesis were also evaluated.

RESULTS

With a median follow-up period of 66.9 months, the overall survival rate was 99.6%, the disease-free survival rate was 96.3%, and the local recurrence-free survival rate was 97.7% at 3 years. Clinician-rated cosmesis (n = 242) was excellent or good in 93.4% of cases and fair or poor in 6.6%. Patient-rated cosmesis (n = 259) was excellent or good in 86.1% and fair or poor in 13.9%. When patients rated themselves differently than their physicians, patients more often rated themselves poorly compared with their physicians (P = .0044, Cochran-Mantel-Haenszel test).

CONCLUSIONS

At a median follow-up of 5 years, an analysis of patients aged <50 years demonstrated that hypofractionated RT was safe and effective, with good to excellent cosmesis as assessed by both clinicians and patients.

Prototype volumetric ultrasound tomography image guidance system for prone stereotactic partial breast irradiation: proof-of-concept

Accurate dose delivery in stereotactic partial breast irradiation (S-PBI) is challenging because of the target position uncertainty caused by breast deformation, the target volume changes caused by lumpectomy cavity shrinkage, and the target delineation uncertainty on simulation computed tomography (CT) images caused by poor soft tissue contrast. We have developed a volumetric ultrasound tomography (UST) image guidance system for prone position S-PBI. The system is composed of a novel 3D printed rotation water tank, a patient-specific resin breast immobilization cup, and a 1D array ultrasound transducer. Coronal 2D US images were acquired in 5° increments over a 360° range, and planes were acquired every 2 mm in elevation. A super-compounding technique was used to reconstruct the image volume. The image quality of UST was evaluated with a BB-1 breast phantom and BioZorb surgical marker, and the results revealed that UST offered better soft tissue contrast than CT and similar image quality to MR. In the evaluated plane, the size and location of five embedded objects were measured and compared to MR, which is considered as the ground truth. Objects' diameters and the distances between objects in UST differ by approximately 1 to 2 mm from those in MR, which showed that UST offers the image quality required for S-PBI. In future work we will develop a robotic system that will be ultimately implemented in the clinic.

Does an integrated boost increase acute toxicity in prone hypofractionated breast irradiation? A randomized controlled trial

BACKGROUND AND PURPOSE

The safety of a simultaneous integrated boost (SIB) in combination with prone hypofractionated whole-breast irradiation (WBI) was investigated.

MATERIALS AND METHODS

167 patients were randomized between WBI with a sequential boost (SeB) or SIB. All patients were treated in prone position to 40.05Gy in 15 fractions to the whole breast. In the control arm, a SeB of 10Gy in 4 fractions (negative surgical margins) or 14.88Gy in 6 fractions (transsection) was prescribed. In the experimental arm a SIB of 46.8 or 49.95Gy (negative and positive surgical margins, respectively) was prescribed.

RESULTS

Patient age was the only significantly different parameter between treatment arms with patients in the SIB arm being slightly older. In both arms, 6/83 patients developed moist desquamation. Grade 2/3 dermatitis was significantly more frequent in the SeB arm (38/83vs 24/83 patients, p=0.037). In the SIB and SeB arm, respectively, 36 patients (43%) and 51 patients (61%) developed pruritus (p=0.015). The incidence of oedema was lower in the SIB arm (59vs 68 patients), but not statistically significant (p=0.071).

CONCLUSIONS

The primary endpoint, moist desquamation, was not significantly different between treatment arms.

Results of a phase I-II study of adjuvant concurrent carboplatin and accelerated radiotherapy for triple negative breast cancer

Purpose: To determine feasibility and explore the clinical efficacy of concurrent radiotherapy and carboplatin as adjuvant treatment of triple negative breast cancer (TNBC). Patients and Methods: Women with Stage I-II TNBC were treated after surgery in a phase I-II prospective trial [NCT01289353]. Weekly carboplatin (AUC = 2.0) was delivered for 6 weeks. Concurrent radiotherapy was delivered in the prone position during weeks 2-4, for a total dose of 40.5 Gy in 15 fractions to the breast, and 46.5 Gy in 17 fractions to the tumor bed. Adverse events (AE) were assessed weekly during treatment, once at 45-60 d, and every 6 mo thereafter, using the Common Terminology Criteria for AE (CTCAE) v3.0. Results: A total of 39 patients accrued and 36 received treatment. Eight patients (22%, exact 95% CI: 10%, 39%) developed grade 2 or greater acute radiation dermatitis. Overall, grade 2 AE were seen in nine and grade 3 in two patients. Twenty-three patients (64%) received additional adjuvant chemotherapy. With a median follow-up of 48 mo, 34/36 (94%) are alive and disease free. One patient died of pulmonary failure with possible but unproven breast cancer recurrence, and one patient died of pelvic malignancy. One patient recurred locally and is alive and disease free after surgical management. Brisk lymphocytic infiltrate was present pre-treatment in 39% of 18 patients with evaluable tumor. Conclusions: Adjuvant concurrent carboplatin and prone accelerated radiotherapy is a well-tolerated and promising treatment of early stage TNBC. The observed 3% compares favorably with the expected 30% recurrence rate within 1-4 y from treatment, warranting further studies.

Correlation between clinically measured breast size and CT-measured breast volume: implications for prone breast radiotherapy

Purpose

To determine if a patient’s breast size accurately correlates with the breast volume measured in the computed tomography (CT) scan, and to determine which sizes correspond to a volume >750 cc; in order to predict which patients will benefit from breast irradiation in the prone position.

Methods

Breast size was calculated as the difference between the thoracic (band) and breast (bust) circumferences. Breast volume was contoured by a radiation oncologist and measured on the simulation CT scan. Pearson’s coefficient was used to evaluate the correlation between both variables. A receiver operating characteristic (ROC) analysis was performed to determine the optimal cut-off point to predict which differences between band and bust would be associated with a volume ≥750 cc.

Results

Fifty-nine patients were included in this study. Mean breast volume was 851·8 cc and mean size difference was 4·7 inches. Pearson’s correlation coefficient was 0·61 (p<0·001). The ROC analysis determined that a difference of 5 inches between the band and bust circumferences was the optimal cut-off point to determine a breast volume of 750 cc.

Conclusions

A significant correlation between breast size as measured in the clinical practice and breast volume measured in the CT scan was found. Among other characteristics, a 5-inch difference between breast band and bust will be the cut-off point to decide if a patient will be treated prone at our institution.

Preplanning prediction of the left anterior descending artery maximum dose based on patient, dosimetric, and treatment planning parameters

PURPOSE

Maximum dose to the left anterior descending artery (LADmax) is an important physical constraint to reduce the risk of cardiovascular toxicity. We generated a simple algorithm to guide the positioning of the tangent fields to reliably maintain LADmax <10 Gy.

METHODS AND MATERIALS

Dosimetric plans from 146 consecutive women treated prone to the left breast enrolled in prospective protocols of accelerated whole breast radiation therapy, with a concomitant daily boost to the tumor bed (40.5 Gy/15 fraction to the whole breast and 48 Gy to the tumor bed), provided the training set for algorithm development. Scatter plots and correlation coefficients were used to describe the bivariate relationships between LADmax and several parameters: distance from the tumor cavity to the tangent field edge, cavity size, breast separation, field size, and distance from the tangent field. A logistic sigmoid curve was used to model the relationship of LADmax and the distance from the tangent field. Furthermore, we tested this prediction model on a validation data set of 53 consecutive similar patients.

RESULTS

A lack of linear relationships between LADmax and distance from cavity to LAD (-0.47), cavity size (-0.18), breast separation (-0.02), or field size (-0.28) was observed. In contrast, distance from the tangent field was highly negatively correlated to LADmax (-0.84) and was used in the models to predict LADmax. From a logistic sigmoid model we selected a cut-point of 2.46 mm (95% confidence interval, 2.19-2.74 mm) greater than which LADmax is <10 Gy (95% confidence interval, 9.30-10.72 Gy) and LADmean is <3.3 Gy.

CONCLUSIONS

Placing the edge of the tangents at least 2.5 mm from the closest point of the contoured LAD is likely to assure LADmax is <10 Gy and LADmean is <3.3 Gy in patients treated with prone accelerated breast radiation therapy.

Impact of tumour bed boost integration on acute and late toxicity in patients with breast cancer: A systematic review

The purpose of this systematic review was to summarise the evidence from studies investigating the integration of tumour bed boosts into whole breast irradiation for patients with Stage 0-III breast cancer, with a focus on its impact on acute and late toxicities. A comprehensive systematic electronic search through the Ovid MEDLINE, EMBASE and PubMed databases from January 2000 to January 2015 was conducted. Studies were considered eligible if they investigated the efficacy of hypo- or normofractionated whole breast irradiation with the inclusion of a daily concurrent boost. The primary outcomes of interest were the degree of observed acute and late toxicity following radiotherapy treatment. Methodological quality assessment was performed on all included studies using either the Newcastle-Ottawa Scale or a previously published investigator-derived quality instrument. The search identified 35 articles, of which 17 satisfied our eligibility criteria. Thirteen and eleven studies reported on acute and late toxicities respectively. Grade 3 acute skin toxicity ranged from 1 to 7% whilst moderate to severe fibrosis and telangiectasia were both limited to 9%. Reported toxicity profiles were comparable to historical data at similar time-points. Studies investigating the delivery of concurrent boosts with whole breast radiotherapy courses report safe short to medium-term toxicity profiles and cosmesis rates. Whilst the quality of evidence and length of follow-up supporting these findings is low, sufficient evidence has been generated to consider concurrent boost techniques as an alternative to conventional sequential techniques.

Prospective Randomized Trial of Prone Accelerated Intensity Modulated Breast Radiation Therapy With a Daily Versus Weekly Boost to the Tumor Bed

PURPOSE

To report the results of a prospective randomized trial comparing a daily versus weekly boost to the tumor cavity during the course of accelerated radiation to the breast with patients in the prone position.

METHODS AND MATERIALS

From 2009 to 2012, 400 patients with stage 0 to II breast cancer who had undergone segmental mastectomy participated in an institutional review board-approved trial testing prone breast radiation therapy to 40.5 Gy in 15 fractions 5 d/wk to the whole breast, after randomization to a concomitant daily boost to the tumor bed of 0.5 Gy, or a weekly boost of 2 Gy, on Friday. The present noninferiority trial tested the primary hypothesis that a weekly boost produced no more acute toxicity than did a daily boost. The recurrence-free survival was estimated for both treatment arms using the Kaplan-Meier method; the relative risk of recurrence or death was estimated, and the 2 arms were compared using the log-rank test.

RESULTS

At a median follow-up period of 45 months, no deaths related to breast cancer had occurred. The weekly boost regimen produced no more grade ≥2 acute toxicity than did the daily boost regimen (8.1% vs 10.4%; noninferiority Z = -2.52; P=.006). No statistically significant difference was found in the cumulative incidence of long-term fibrosis or telangiectasia of grade ≥2 between the 2 arms (log-rank P=.923). Two local and two distant recurrences developed in the daily treatment arm and three local and one distant developed in the weekly arm. The 4-year recurrence-free survival rate was not different between the 2 treatment arms (98% for both arms).

CONCLUSIONS

A tumor bed boost delivered either daily or weekly was tolerated similarly during accelerated prone breast radiation therapy, with excellent control of disease and comparable cosmetic results.

Breast, chest wall, and nodal irradiation with prone set-up: Results of a hypofractionated trial with a median follow-up of 35 months

PURPOSE

To test clinical feasibility, safety, and toxicity of prone hypofractionated breast, chest wall, and nodal radiation therapy.

METHODS AND MATERIALS

Following either segmental or total mastectomy with axillary node dissection, patients were treated in an institutional review board-approved prospective trial of prone radiation therapy to the breast, chest wall, and supraclavicular and level III axillary lymph nodes. A dose of 40.5 Gy/15 fractions with a concomitant daily boost to the tumor bed of 0.5 Gy (total dose, 48 Gy) was prescribed. In postmastectomy patients, the same treatment was prescribed, but without a tumor bed boost. The primary endpoint was incidence of >grade 2 acute skin toxicity. The secondary endpoints were feasibility of treatment using prone set-up, compliance with protocol-defined dosimetric constraints, and incidence of late toxicity. A dosimetric comparison was performed between protocol plans (prone) and nonprotocol plans (supine), targeting the same treatment volumes.

RESULTS

Sixty-nine patients with stage IB-IIIA breast cancer enrolled in this trial. Surgery was segmental mastectomy (n = 45), mastectomy (n = 23), and bilateral mastectomy (n = 1), resulting in 70 cases. None experienced >grade 2 acute skin toxicity according to the Common Terminology Criteria for Adverse Events, v 3.0, meeting our primary endpoint. Ninety-six percent of patients could be treated with this technique prone. However, 17 plans (24%) exceeded protocol constraints to the brachial plexus. Maximum long-term toxicity was 1 grade 2 arm lymphedema, 1 grade 3 breast retraction, and no occurrence of brachial plexopathy. Dosimetric comparison of protocol with nonprotocol plans demonstrated significantly decreased lung and heart doses in prone plans.

CONCLUSIONS

Prone hypofractionated breast, chest wall, and nodal radiation therapy is safe and well tolerated in this study. Although the initial pattern of local and regional control is encouraging, longer follow-up is warranted for efficacy and late toxicity assessment, particularly to the brachial plexus.