Intensity modulated radiation therapy with simultaneous integrated boost in early breast cancer irradiation. Report of feasibility and preliminary toxicity

Deep learning-based prediction of the dose-volume histograms for volumetric modulated arc therapy of left-sided breast cancer

BACKGROUND

The advancements in artificial intelligence and computational power have made deep learning an attractive tool for radiotherapy treatment planning. Deep learning has the potential to significantly simplify the trial-and-error process involved in inverse planning required by modern treatment techniques such as volumetric modulated arc therapy (VMAT). In this study, we explore the ability of deep learning to predict organ-at-risk (OAR) dose-volume histograms (DVHs) of left-sided breast cancer patients undergoing VMAT treatment based solely on their anatomical characteristics. The predicted DVHs could be used to derive patient-specific dose constraints and dose objectives, streamlining the treatment planning process, standardizing the quality of the plans, and personalizing the treatment planning.

PURPOSE

This study aimed to develop a deep learning-based framework for the prediction of organ-specific dose-volume histograms (DVH) based on structures delineated for left-sided breast cancer treatment.

METHODS

We used a dataset of 249 left-sided breast cancer patients treated with tangential VMAT fields. We extracted delineated structures and dose distributions for each patient and derived slice-by-slice DVHs for planning target volume (PTV) and organs-at-risk. The patients were divided into training (70%, n = 174), validation (10%, n = 24), and test (20%, n = 51) sets. Collected data were used to train a deep learning model for the prediction of the DVHs based on the delineated structures. The developed deep learning model comprised a modified DenseNet architecture followed by a recurrent neural network.

RESULTS

In the independent test set (n = 51), the point-wise differences in the slice-by-slice DVHs between the clinical and predicted DVHs were small; the mean squared errors were 3.53, 1.58, 2.28, 3.37, and 1.44 [×10-4] for PTV, heart, ipsilateral lung, contralateral lung, and contralateral breast, respectively. With the derived cumulative DVHs, the mean absolute difference ± standard deviation of mean doses between the clinical and the predicted DVH were 0.08 ± 0.04 Gy, 0.24 ± 0.22 Gy, 0.73 ± 0.46 Gy, 0.07 ± 0.06 Gy, and 0.14 ± 0.14 Gy for PTV, heart, ipsilateral lung, contralateral lung, and contralateral breast, respectively.

CONCLUSIONS

The deep learning-based approach enabled automatic and reliable prediction of the DVH based on delineated structures. The predicted DVHs could potentially serve as patient-specific clinical goals used to aid treatment planning and avoid suboptimal plans or to derive optimization objectives and constraints for automated treatment planning.

Irradiation Affects Adipose-Derived Stem Cells and Wound Healing Depending on Radiation Dose and Frequency

BACKGROUND

Radiation therapies are often associated with permanent devitalization in the surrounding tissue. The authors hypothesized that stem cells are damaged depending on each irradiation dose and frequency of fractionated radiotherapies, which results in impaired tissue function, including wound-healing capacity.

METHODS

Susceptibility of human adipose-derived stem cells (ASCs) to a single irradiation (0 to 10 Gy) was assessed in vitro. In vivo chronic radiation effects were also assessed on mouse dorsal skin ( n = 4 to 5) for 6 months after a total of 40 Gy irradiation (0 Gy as control) using 1 of 3 fractionated protocols (2 Gy daily for 20 days, 10 Gy weekly for 4 weeks, or 10 Gy monthly for 4 months). Oxygen partial pressure, oxygen saturation of hemoglobin, and dorsal skin viscoelasticity were measured periodically, and wound healing and tissue immunohistology were compared at 6 months.

RESULTS

A single irradiation of cultured human ASCs resulted in a dose-dependent increase in cell death up to 2 Gy but with no further increases between 2 and 10 Gy. Most of the apoptotic ASCs were in the proliferation phase. Among the 3 in vivo irradiation protocols, the 2 Gy×20 group had the most severe chronic tissue damage (ie, skin dysfunction, subcutaneous atrophy, depletion of CD34 + stem cells) 6 months after the irradiation. Wound healing was also impaired most significantly in the 2 Gy×20 group.

CONCLUSION

These results have important clinical implications for surgeons and radiotherapists in the timing of surgical interventions and the optimization of fractionation protocols.

CLINICAL RELEVANCE STATEMENT

Irradiation damages stem cells depending on the radiation dose and frequency. Using the ultimately optimized protocol, surgeons can minimize the long-term functional deficits of radiated tissue without losing the anticancer efficacy of radiation therapy.

Association of Radiation-Induced Acute Esophagitis With Dosimetric Parameters of Oesophagus in Breast Carcinoma Patients Receiving Supraclavicular Nodal Irradiation

INTRODUCTION

We conducted this investigation to ascertain the dosimetric properties such as the mean and maximum radiation dosage during radiotherapy as well as the extent of radiation exposure to the esophagus. These factors can potentially impact the development of esophagitis in breast cancer patients undergoing supraclavicular radiation.

METHODOLOGY

 From January to June 2023, an observational study was conducted at Bangabandhu Sheikh Mujib Medical University in Bangladesh. The patients received radiation therapy (40.05 Gy in 15 parts) to the chest wall and supraclavicular node for three weeks. We were able to guess the following from the dose volume histogram (DVH) data: the length of the esophagus in the treatment area (i.e., the size of the esophagus that was visible on the planning CT scan), the maximum dose (Dmax), the mean dose (Dmean), and the volume of the 10Gy (V10Gy) and 20Gy (V20Gy) doses that were given to the esophagus. During radiotherapy, patients were checked on once a week, and the radiotherapy oncology group was used to evaluate and grade esophagitis Results: Patients with left-sided breast cancer showed a higher Dmean, Dmax, and length of the esophagus compared to those with right-sided breast cancer. Specifically, the Dmean was 6.7 (±2.1) Gy, the Dmax was 39.2 (±1.5) Gy, and the length of the esophagus was 6.1 (±1.2) Gy. Patients with left breast cancer had elevated V10Gy and V20Gy values for the esophagus, but the difference was not statistically significant. The incidence of V10Gy for right-sided breast cancer and left-sided breast cancer was 4.2% (±2.6%) and 19.8% (±9.2%), respectively. The V20Gy was 2.4% (±0.9%) for right-sided breast cancer and 13.09% (±5.0%) for left-sided breast cancer Conclusion: In conclusion, there is a strong association between the mean oesophageal dose and radiation to the left supraclavicular region following surgery in women with breast cancer and acute esophagitis. We can reduce esophageal toxicity by prescribing dose restrictions and performing precise delineation of the esophagus.

Cardiac dose in the treatment of synchronous bilateral breast cancer patients between three different radiotherapy techniques (VMAT, IMRT, and 3D CRT)

PURPOSE

Synchronous bilateral irradiation of both mammary glands and chest wall is a challenging task due to technical difficulties and limited evidence supporting an optimal technique to improve treatment outcomes. We studied and compared the dosimetry data of three radiotherapy techniques to select the most optimal one.

METHODS

We compared three-dimensional conformal radiation treatment (3D CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) during irradiation of synchronous bilateral breast cancer in nine patients followed by examination of dose distribution to the cardiac conduction system (SA node, AV node and Bundle of His), myocardium, lungs, left anterior descending artery (LADA) and right coronary artery (RCA) .

RESULTS

VMAT is the most sparing technique for SBBC treatment. Even though doses to the SA node, AV node and Bundle of His were higher with VMAT (D_mean were 3.75 ± 0.62, 2.58 ± 0.83 and 3.03 ± 1.18 Gy respectively) compared with 3D CRT (D_mean were 2.61 ± 0.66, 1.52 ± 0.38 and 1.88 ± 0.70 Gy respectively), this difference is statistically insignificant. Doses to the right and left lung (average D_mean = 12.65 ± 3.20 Gy, V_20Gy = 24.12 ± 6.25%), myocardium (D_mean = 5.33 ± 1.51 Gy, V_10Gy = 9.80 ± 3.83%, V_20Gy = 7.19 ± 3.15%, V_25Gy = 6.20 ± 2.93%), and LADA (D_mean = 10.04 ± 4.92 Gy, V_20Gy = 18.17 ± 13.24% and V_25Gy = 15.41 ± 12.19%) were highest with 3D CRT. The highest  D_mean in the cardiac conduction system (5.30 ± 2.23, 3.15 ± 1.61 and 3.89 ± 1.85 Gy respectively) was observed with IMRT, and a similar effect was noted in RCA (D_mean = 7.48 ± 2.11 Gy).

CONCLUSION

VMAT is the optimal and satisfactory radiation therapy technique for sparing organs at risk (OARs). With VMAT, a lower D_mean value was noted in the myocardium, LADA, and lungs. The use of 3D CRT significantly increases the dose of radiation reaching the lungs, myocardium, and LADA, which can subsequently cause cardiovascular and lung complications, but not in the cardiac conduction system.

Long-term oncological outcomes of hypofractionated versus conventional fractionated whole breast irradiation with simultaneous integrated boost in early-stage breast cancer

Purpose

For patients with early breast cancer who undergo breast-conserving surgery, adjuvant whole breast irradiation (WBI) with simultaneous integrated boost (SIB) results in lower radiotherapy fractions. Published studies have shown that both conventional fraction with SIB (C-SIB) and hypofractionation with SIB (H-SIB) seem to be safe and feasible. In this study, we sought to compare the oncologic outcomes between C-SIB and H-SIB in early-stage breast cancer.

Materials and Methods

Stage I–II breast cancer patients who received adjuvant WBI with SIB between January 2008 and December 2017 were retrospectively reviewed. The radiation dose in the C-SIB group was 50 Gy and 65 Gy in 25 daily fractions, while in the H-SIB group, it was 43.2 Gy and 52.8 Gy in 16 daily fractions to the whole breast and tumor bed, respectively.

Results

A total of 188 patients, 103 in the C-SIB group and 85 in the H-SIB group, were included. With a median follow-up time of 87 months, 7-year locoregional control of C-SIB was comparable to H-SIB (95.8% vs. 97.4%, p = 0.964). The 7-year distant metastasis-free survival rates of C-SIB and H-SIB were 89.9% and 95.9% (p = 0.111), while the 7-year disease-free survival rates were 84.2% and 95.4%, respectively (p = 0.176). In multivariate analysis, there was no significant prognostic factor associated with better overall survival.

Conclusion

H-SIB provided comparable locoregional control to C-SIB. With the advantage of a shorter radiotherapy course, H-SIB could be a favorable option for WBI in early-stage breast cancer.

Correlation between toxicity and dosimetric parameters for adjuvant intensity modulated radiation therapy of breast cancer: a prospective study

ORCID: 0000–0001-6019–7309. In the treatment of breast cancer, intensity-modulated radiation therapy (IMRT) reportedly reduces the high-dose irradiation of at-risk organs and decreases the frequency of adverse events (AEs). Comparisons with conventional radiotherapy have shown that IMRT is associated with lower frequencies of acute and late-onset AEs. Here, we extended a prospective, observational, single-center study of the safety of IMRT to a second investigating center. Patients scheduled for adjuvant IMRT after partial or total mastectomy were given a dose of 50 Gy (25 fractions of 2 Gy over 5 weeks), with a simultaneous integrated boost in patients having undergone conservative surgery. 300 patients were included in the study, and 288 were analyzed. The median follow-up period was 2.1 years. The 2-year disease-free survival rate [95% CI] was 93.4% [89.2–96.0%]. Most AEs were mild. The most common AEs were skin-related—mainly radiodermatitis [in 266 patients (92.4%)] and hyperpigmentation (in 178 (61.8%)). 35% and 6% of the patients presented with grade 2 acute skin and esophageal toxicity, respectively. Only 4 patients presented with a grade 3 event (radiodermatitis). Smoking (odds ratio) [95% CI] = 2.10 [1.14–3.87]; p = 0.017), no prior chemotherapy (0.52 [0.27–0.98]; p = 0.044), and D98% for subclavicular skin (1.030 [1.001–1.061]; p = 0.045) were associated with grade ≥ 2 acute AEs. In a univariate analysis, the mean dose, (p < 0.0001), D2% (p < 0.0001), D50% (p = 0.037), D95% (p = 0.0005), D98% (p = 0.0007), V30Gy (p < 0.0001), and V45Gy (p = 0.0001) were significantly associated with grade ≥ 1 acute esophageal AEs. In a multivariate analysis, D95% for the skin (p < 0.001), D98% for the subclavicular skin and low D95% for the internal mammary lymph nodes were associated with grade ≥ 1 medium-term AEs. The safety profile of adjuvant IMRT after partial or total mastectomy is influenced by dosimetric parameters.

Trial registration: ClinicalTrials.gov NCT02281149.

Acute and intermediate toxicity of 3-week radiotherapy with simultaneous integrated boost using TomoDirect: prospective series of 287 early breast cancer patients

AIMS

To report toxicity of a hypofractionated scheme of whole-breast (WB) intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) to the tumor bed (TB) using Tomotherapy^® with Direct modality.

METHODS

Patients with early breast cancer, undergoing radiotherapy (RT) in 15 daily fractions to WB (prescription dose 40.05 Gy) and SIB to the TB (48 Gy), between 2013 and 2017, was analyzed. Primary endpoint was acute and intermediate toxicity assessed at the end and within 6 months from RT, according to Radiation Therapy Oncology Group (RTOG) scale. Secondary endpoints included early chronic toxicity at 12-months follow-up, using the Late Effects Normal Tissue Task Subjective, Objective, Management, and Analytic (LENT-SOMA) scale, and cosmesis using Harvard criteria.

RESULTS

The study population was of 287 patients. Acute and intermediate toxicity was collected among 183 patients with data available at the end of RT and within 6 months, 85 (46%) experienced G2 toxicity and 84 (46%) G1 toxicity, while 14 (8%) did not report toxicity at any time. A significant reduction of any grade toxicity was observed between the two time points, with the majority of patients reporting no clinically relevant toxicity at 6 months. At univariate analysis, age < 40 years, breast volume > 1000 cm³ and D_max ≤ 115% of prescription dose were predictive factors of clinically relevant acute toxicity (G ≥ 2) at any time. At multivariable analysis, only age and breast volume were confirmed as predictive factors, with Relative Risks (95% Confidence Intervals): 2.02 (1.13-3.63) and 1.84 (1.26-2.67), respectively. At 12-month follow-up, 113 patients had complete information on any toxicity with 53% of toxicity G < 2, while cosmetic evaluation, available for 102 patients, reported a good-excellent result for 86% of patients.

CONCLUSIONS

Hypofractionated WB IMRT with a SIB to the TB, delivered with TomoDirect modality, is safe and well-tolerated. Most patients reported no toxicity after 6 months and good-excellent cosmesis. Predictive factors of clinically relevant toxicity might be considered during treatment planning in order to further reduce side effects.

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.

Prospective Study of Intensity-Modulated Radiation Therapy for Locally Advanced Breast Cancer

Simple Summary

Tomotherapy is a modern intensity-modulated radiotherapy technique, whose aim is to reduce the high doses delivered to organs at risk. Thus, we conducted a prospective study evaluating the early and medium-term toxicities, the patient’s quality of life, and the aesthetic outcomes (evaluated by both physicians and patients) of tomotherapy for breast cancer. We wanted to show that this treatment is very well tolerated, with low-grade acute toxicities, and has only a moderate impact on patients’ quality of life and aesthetic outcome, in order to support its larger use in this very frequent situation.

Abstract

The objective of this study was to evaluate the acute and medium-term toxicities, the quality of life, and aesthetic results of patients with breast cancer (BC) treated with tomotherapy. This was a prospective study, including patients with BC treated by tomotherapy. Radiation therapy delivered 50 Gy in 25 fractions to the breast or chest wall and to lymph node areas, with a simultaneous integrated boost at a dose of 60 Gy at the tumor bed in cases of breast conservative surgery. We included 288 patients, 168 and 120 treated with breast-conserving surgery and mastectomy respectively. Two hundred sixty patients (90.3%) received lymph node irradiation. Median follow-up was 25 months (6–48). Acute dermatitis was observed in 278 patients (96.5%), mostly grade 1 (59.7%). The aesthetic aspect of the breast at one year was reported as “good” or “excellent” in 84.6% of patients. The patients’ quality of life improved over time, especially those treated with chemotherapy. The two-year overall survival and disease-free survival were 97.8% (95% confidence interval (CI): 94.1–99.2%), and 93.4% (95% CI: 89.2–96.0%) respectively. Tomotherapy for locally advanced BC has acceptable toxicity, supporting its use in this indication; however, longer follow-up is needed to assess long-term outcomes.

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.

Adjuvant whole breast radiotherapy with simultaneous integrated boost to tumor bed with intensity modulated radiotherapy technique in elderly breast cancer patients

Background

Adjuvant whole breast radiotherapy is the standard of care for breast cancer patients after partial mastectomy. Intensity-modulated radiation therapy (IMRT) has been reported to reduce acute toxicities compared to conventional radiotherapy. IMRT with simultaneous integrated boost (SIB) technique can deliver higher doses to tumor bed and irradiate whole breast with a lower dose level to shorten overall treatment duration. This study presents the long-term results of adjuvant IMRT with SIB in elderly breast cancer patients who received partial mastectomy.

Methods

From January 2007 to January 2018, 93 elder breast cancer patients (≥65-year-old) who received IMRT with SIB technique after partial mastectomy were reviewed retrospectively. The axillary areas were managed with either sentinel lymph node biopsies or axillary lymph node dissection. The dose to whole breast was 50.4 Gy in 28 fractions in all patients and the dose to tumor bed was 61.6 to 66.4 Gy in 28 fractions. The primary end point is locoregional control. Secondary end points include: overall survival, breast cancer-specific survival, distant-metastases-free survival, disease-free survival, and acute and chronic toxicities.

Results

The median follow-up was 56.1 months. One patient had ipsilateral breast tumor recurrence, 3 patients had regional lymph node recurrence, and 9 patients had distant metastases. Death occurred in 5 patients, including 3 patients died of breast cancer progression. Five-year overall survival is 96.3% and 5-year locoregional recurrence-free survival is 96.4%. The 5-year breast cancer specific survival and 5-year distant metastases-free survival is 97.5% and 87.2%, respectively. Seven patients developed second primary cancer after RT. Eighty-one point seven percent patients had acute grade 1 dermatitis while 18.3% suffered from grade 2 dermatitis. The incidence of grade 1 pneumonitis and grade 1 stomatitis was 4.3% and 8.6%, respectively.

Conclusions

Adjuvant IMRT with SIB technique is a safe and effective treatment strategy for elderly breast cancer patients after partial mastectomy.

Intensity-modulated radiation therapy with simultaneous integrated boost for locally advanced breast cancer: a prospective study on toxicity and quality of life

Radiotherapy after breast conserving surgery and mastectomy with node positive disease has been shown to reduce risk of recurrence and mortality in the treatment of breast cancer. Intensity-modulated radiation therapy (IMRT) after conservative surgery offers several advantages over conventional RT including improved acute and late toxicity and quality of life (QoL). We undertook this study to prospectively evaluate acute (≤90 days after last dose of radiotherapy) and long-term (>90 days) cutaneous, esophageal, and fibrosis toxicity and QoL in breast cancer patients treated by adjuvant IMRT after breast surgery. We included patients with complex volumes for which 3D RT does not allow a good coverage of target volumes and sparing organs at risk. We report here an interim analysis with a median follow-up of 13.1 months (range, 6.5–25.9 months). Most of the acute toxicity was cutaneous (95.9%) and oesophageal (59.6%), and mostly grade 1 and 2. Medium-term cutaneous toxicity rate was 25.6%, and mostly grade 1. Medium-term esophageal toxicity was rare (1.8%). In this series acute oesophageal toxicity was found to be associated with dosimetric factors. QoL was well preserved throughout the study, and aesthetic outcomes were good. Based on these data, tomotherapy may be a favorable alternative to other techniques in patients needing a complex irradiation of the breast and lymph node volumes.

Intensity-modulated radiotherapy and hypofractionated volumetric modulated arc therapy for elderly patients with breast cancer: comparison of acute and late toxicities

PURPOSE

To evaluate the differences between conventional fractionated intensity-modulated radiotherapy (IMRT) and hypofractionated (HypoRT) volumetric modulated arc therapy (VMAT) in elderly women affected by early-stage breast cancer (BC) in terms of RT-related acute/late side effect.

MATERIALS AND METHODS

Between October 2011 and July 2015, 80 consecutive elderly BC patients were treated with IMRT for 5 weeks (40 patients) or HypoRT-VMAT for 3 weeks (40 patients). Inclusion criteria were: age ≥ 70 years, early BC (pT1-2 pN0-1), no prior neoadjuvant chemotherapy and non-metastatic disease. For patients receiving IMRT or HypoRT-VMAT, a total dose of 50 Gy (25 fractions) or 40.5 Gy (15 fractions) was prescribed to the whole ipsilateral breast, respectively. All patients received a simultaneously integrated boost up to a total dose of 60 Gy for IMRT and 48 Gy for HypoRT-VMAT. Acute and late side effects were evaluated using the RTOG/EORTC radiation morbidity scoring system.

RESULTS

With a median follow-up of 45 months, acute skin toxicity was overall very low, with grade 1 in 25 cases (62.5%) of the IMRT group and 21 cases (52.5%) of the HypoRT-VMAT group, while grade 2 toxicity was reported in 10 IMRT patients (25%) and 1 HypoRT-VMAT patient (2.5%) (p = 0.001). Regarding late adverse events, only grade 1 skin toxicity was recorded.

CONCLUSION

The present study showed that whole breast IMRT and HypoRT-VMAT are feasible and well tolerated in early-stage BC elderly patients and that HypoRT-VMAT is affected by lower risk of acute and late RT-related side effects.

Hypofractionation with concomitant boost using intensity-modulated radiation therapy in early-stage breast cancer in Mexico

Aim

To evaluate whether hypofractionation with integrated boost to the tumour bed using intensity-modulated radiation therapy is an acceptable option and to determine whether this treatment compromises local control, toxicity and cosmesis.

Background

Retrospective studies have demonstrated that patients who are treated with HF and integrated boost experience adequate local control, a dosimetric benefit, decreased toxicity and acceptable cosmesis compared with conventional fractionation.

Materials and methods

A retrospective, observational and longitudinal study was conducted from January 2008 to June 2015 and included 34 patients with breast cancer (stage 0-II) who were undergoing conservative surgery.The prescribed doses were 45 Gy in 20 fractions (2.25 Gy/fraction) to the breast and 56 Gy in 20 fractions (2.8 Gy/fraction) to the tumour bed.

Results

Thirty-four patients were included. The mean follow-up was 49.29 months, and the mean age was 52 years. The mean percentage of PTV from the mammary region that received 100% of the prescribed dose was 97.89% (range 95-100), and the mean PTV percentage of the tumour bed that received 100% of the dose was 98% (95-100).The local control and the overall survival were 100%, and the cosmesis was good in 82% of the patients. Grade 1 acute toxicity was present in 16 patients (47%), and grade 1 chronic toxicity occurred in 6 cases (18%).

Conclusion

The results of the present study demonstrate that hypofractionation with integrated boost using intensity-modulated radiation therapy is an acceptable option that provides excellent local control and low toxicity.

Chair Heterogeneity Index: Describing the dose heterogeneity inside the tumor volume where there is a boost volume

In this report, Chair Heterogeneity Index (CHI) was introduced to assess the dose heterogeneity inside the target with a boost volume. CHI was defined by dividing (V_Rx − V_Dl) by (V_Dm − V_Dh): V_Rx, V_Dl, V_Dm and V_Dh were four points selected from the target cumulative dose volume histogram curve. The effectiveness of CHI was validated by assessing the treatment plans for nasopharyngeal cancer (NPC, 12 cases), breast cancer after breast-conserving-surgery (BC, 10 cases), and stereotactic radiosurgery after whole brain irradiation (SRS, 9 cases). Our results indicate that both CHI and HI of the target can distinguish Volumetric Modulated Arc Therapy (VMAT) from Intensity Modulated Radiation Therapy (IMRT, p < 0.05) while the mean differences in CHI (NPC 1.16, BC 1.19 and SRS 3.3) were larger than those in HI (NPC 0.03, BC 0.02 and SRS 0.02). In addition, CHI of the combination volume (the target minus the boost) were statistically higher in VMAT than IMRT in all three kinds of cancer. In conclusion, CHI was effective in assessing the dose heterogeneity inside a target containing a boost volume.

Advantages of a technique using two 50 degree arcs in simultaneous integrated boost radiotherapy for left-sidebreast cancer

This study evaluated radiotherapy techniques with 15 cases for simultaneous integrated boost to treat whole left breast and tumor bed following breast conserving surgery. Treatment plans were generated using three techniques: volumetric modulated arc therapy (VMAT) with a partial arc of 190° (1ARC), VMAT with two tangential mini-arcs of 50° each (2TARC) and intensity modulated radiation therapy with four fixed angle fields (4IMRT). Dosimetric parameters for the whole breast (Target), the boost tumor bed (Boost), and surrounding normal organs were compared. Chair Index (CHI) was introduced to evaluate the dose homogeneity in Target given the two levels of prescription dose. The dose coverage in Target was better in 1ARC and 2TARC than that in 4IMRT. The mean CHI in 1ARC (2.47) and 2TARC (2.62) were higher than that in 4IMRT (1.71, p < 0.05), and this indicated the dose homogeneity of Target was better in 1ARC and 2TARC than that in 4IMRT. The mean doses to right lung, and contralateral breast in 4IMRT were lower than those in 2TARC but the differences between them were small. 2TARC was better than 4IMRT with respect to the dose to ipsilateral lung and heart. Overall, 2TARC was optimal among three techniques.

Dosimetric comparison of simultaneous integrated boost versus concomitant electron boost in radiotherapy treatment of breast cancer

Background

The aim of this study was to compare the dosimetric parameters and effects of simultaneous integrated boost (SIB) and traditional sequential electron boost, after helical tomotherapy, because of the lack of studies in this field in the current literature.

Methods

Computed tomographic data of 14 patients who received SIB in 2012–2015 were collected from Hong Kong Sanatorium & Hospital. New tomotherapy with SIB plans and tomotherapy with sequential boost plans were generated for each patient, and results were compared.

Results

Conformation number, mean dose, dose received by 95% volume (both sides), ipsilateral lung volume receiving 20 Gy (V20) and skin dose (right side) were found to be significantly better for SIB (p<0·05), however coverage index and gross target volume dose showed no significant difference, and heart dose was significantly higher for SIB on the right side.

Conclusion

Tomotherapy with SIB may be able to offer less organ at risk dose (except for the heart), while maintaining the ability to deliver adequate dose coverage.

Classification of chronic radiation-induced ulcers in the chest wall after surgery in breast cancers

BACKGROUND AND PURPOSE

To explore the methods of clinical classification in chronic radiation-induced ulcers in the chest wall (CRUCWs).

MATERIALS AND METHODS

A total of 64 patients with CRUCWs were treated. We divided the cases into 3 types (mild, moderate, or severe) according to their clinical manifestations. Conservative treatments, axial-pattern myocutaneous or local flaps, or filleted flaps were applied correspondingly.

RESULTS

The cases were divided as follows: mild (n = 11), moderate (n = 45), and severe (n = 8). Eight cases were cured by conservative surgical therapy. One case had a recurrence 6 months after conservative therapy and was cured by a latissimus dorsi myocutaneous flap. The transferred flaps all survived, including 26 transverse rectus abdominis myocutaneous flaps, 8 longitudinal rectus abdominis myocutaneous flaps, 6 latissimus dorsi myocutaneous flaps, 3 contralateral breast flaps, 5 lateral thoracic rotation flaps, and 7 filleted flaps. In 2 transverse rectus abdominis myocutaneous flaps and 2 latissimus dorsi myocutaneous flaps, distal necrosis appeared in small areas. The resulting wounds were salvaged with skin graft and full healing was achieved.

CONCLUSION

CRUCWs can be divided into three types. Surgical methods should vary with distinguished classifications. The effective classification of CRUCWs has definite instructive significance on the selection of surgical approaches.

[Technique of complex mammary irradiation: Mono-isocentric 3D conformational radiotherapy and helical tomotherapy]

PURPOSE

To evaluate the dosimetric contribution of helical tomotherapy for breast cancers compared with conformal radiotherapy in mono-isocentric technique.

PATIENTS AND METHOD

For 23 patients, the dosimetric results in mono-isocentric 3D conformational radiotherapy did not satisfy the constraints either of target volumes nor organs at risk. A prospective dosimetric comparison between mono-isocentric 3D conformational radiotherapy and helical tomotherapy was therefore carried out.

RESULTS

The use of helical tomotherapy showed a benefit in these 23 patients, with either an improvement in the conformity index or homogeneity, but with an increase in low doses. Of the 23 patients, two had pectus excavatum, five had past thoracic irradiation and two required bilateral irradiation. The other 14 patients had a combination of morphology and/or indication of lymph node irradiation. For these patients, helical tomotherapy was therefore preferred to mono-isocentric 3D conformational radiotherapy.

CONCLUSIONS

Tomotherapy appears to provide better homogeneity and tumour coverage. This technique of irradiation may be justified in the case of morphological situations such as pectus exavatum and in complex clinical situations. In other cases, conformal radiotherapy in mono-isocentric technique remains to be favoured.

To clip or not to clip the breast tumor bed? A retrospective look at the geographic miss index and normal tissue index of 110 patients with breast cancer

OBJECTIVE

Planning of breast radiation for patients with breast conserving surgery often relies on clinical markers such as scars. Lately, surgical clips have been used to identify the tumor location. The purpose of this study was to evaluate the geographic miss index (GMI) and the normal tissue index (NTI) for the electron boost in breast cancer treatment plans with and without surgical clips.

MATERIAL AND METHODS

A retrospective descriptive study of 110 consecutive post-surgical patients who underwent breast-conserving treatment in early breast cancer, in which the clinical treatment field with the radiologic (clipped) field were compared and GMI/NTI for the electron boost were calculated respectively.

RESULTS

The average clinical field was 100 mm (range, 100-120 mm) and the clipped field was 90 mm (range, 80-100 mm). The average GMI was 11.3% (range, 0-44%), and the average NTI was 27.5% (range, 0-54%). The GMI and NTI were reduced through the use of intra-surgically placed clips.

CONCLUSION

The impact of local tumor control on the survival of patients with breast cancer is also influenced by the precision of radiotherapy. Additionally, patients demand an appealing cosmetic result. This makes "clinical" markers such as scars unreliable for radiotherapy planning. A simple way of identifying the tissue at risk is by intra-surgical clipping of the tumor bed. Our results show that the use of surgical clips can reduce the diameter of the radiotherapy field and increase the accuracy of radiotherapy planning. With the placement of surgical clips, more tissue at risk is included in the radiotherapy field. Less normal tissue receives radiotherapy with the use of surgical clips.

Synchronous bilateral breast cancer irradiation: clinical and dosimetrical issues using volumetric modulated arc therapy and simultaneous integrated boost

OBJECTIVES

The aim of the present retrospective analysis was to evaluate dosimetric parameters, feasibility and outcome for Synchronous Bilateral Breast Cancer (SBBC) patients treated with adjuvant radiotherapy (RT) by Volumetric Modulated Arc Therapy (VMAT).

METHODS

From September 2011 to April 2016, 1100 Breast Cancer (BC) patients were referred to our institution to receive adjuvant breast RT, and those with SBBC were selected for the present analysis. A total of 16 patients were identified. A total dose of 50 Gy in 25 fractions was prescribed to the Planning Target Volume of the whole bilateral breast (PTV_BN) with or without the supraclavicular and infraclavicular nodes, while a total dose of 60 Gy in 25 fractions was prescribed to the surgical bed (PTV_boost). Several V _xGy and Dx% parameters were analyzed for the PTVs, together with Conformity and Homogeneity indexes (CI, HI), and for the critical Organs at risk (OARs), lungs and heart first.

RESULTS

With a median follow-up of 24 months, no acute or late side effects more than grade 2 were observed. All patients are alive without any sign of disease. For target dose coverage, our observed inter-patients averages (±1 sd) were V _{95% Dp} = 96.7 ± 1.6% (96.3 ± 1.8%) to the left (right) PTV_BN, V _{95% Dp} = 98.6 ± 2.7% (99.4 ± 0.9%) to the left (right) PTV_boost, and D _2% = 64.4 ± 1.8 Gy (65.0 ± 2.0 Gy) to the left (right) PTV_boost, respectively. With regard to the heart, the inter-patient average of D _mean was 8.3 ± 3.3 Gy. For the lungs, the inter-patient average of D _mean, V _5 Gy and V _20 Gy were 11.8 ± 2.3 Gy, 78.9 ± 15.3% and 15.7 ± 5%, respectively.

CONCLUSIONS

The present retrospective analysis showed the feasibility, tolerability and safety of VMAT in the treatment of SBBC patients. Further studies are necessary to confirm these preliminary data.

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.

Comparison of two radiation techniques for the breast boost in patients undergoing neoadjuvant treatment for breast cancer

OBJECTIVE

After breast conservative surgery (BCS) and whole-breast radiotherapy (WBRT), the use of boost irradiation is recommended especially in patients at high risk. However, the standard technique and the definition of the boost volume have not been well defined.

METHODS

We retrospectively compared an anticipated pre-operative photon boost on the tumour, administered with low-dose fractionated radiotherapy, and neoadjuvant chemotherapy with two different sequential boost techniques, administered after BCS and standard adjuvant WBRT: (1) a standard photon beam (2) and an electron beam technique on the tumour bed of the same patients. The plans were analyzed for the dosimetric coverage of the CT-delineated irradiated volume. The minimal dose received by 95% of the target volume (D95), the minimal dose received by 90% of the target volume (D90) and geographic misses were evaluated.

RESULTS

15 patients were evaluated. The sequential photon and electron boost techniques resulted in inferior target volume coverage compared with the anticipated boost technique, with a median D95 of 96.3% (range 94.7-99.6%) and 0.8% (range 0-30%) and a median D90 of 99.1% (range 90.2-100%) and 54.7% (range 0-84.8%), respectively. We observed a geographic miss in 26.6% of sequential electron plans. The results of the anticipated boost technique were better: 99.4% (range 96.5-100%) and 97.1% (range 86.2-99%) for median D90 and median D95, respectively, and no geographic miss was observed. We observed a dose reduction to the heart, with left-sided breast irradiation, using the anticipated pre-operative boost technique, when analyzed for all dose-volume parameters. When compared with the sequential electron plans, the pre-operative photon technique showed a higher median ipsilateral lung Dmax.

CONCLUSION

Our data show that an anticipated pre-operative photon boost results in a better coverage with respect to the standard sequential boost while also saving the organs at risk and consequently fewer side effects.

ADVANCES IN KNOWLEDGE

This is the first dosimetric study that evaluated the association between an anticipated boost and neoadjuvant chemotherapy treatment.

Reducing Heart dose during Left Breast Cancer Radiotherapy: Comparison among 3 Radiation Techniques

Purpose

Breast cancer survivors have a high risk of cardiac death as a consequence of heart irradiation during left breast tangential radiotherapy (RT). This study compares the cardiac dose delivered by standard 3D conformal tangential RT (CRT) to that delivered by prospective-gating RT (PGRT) or 5-field intensity-modulated RT (IMRT).

Methods

Patients with early left breast cancer, referred for adjuvant RT to our institution, were enrolled in this study. For each patient, 2 simulation computed tomography scans were acquired: the first during free breathing, and the second on prospective gating during deep inspiration breath-hold. The scans were monitored by the Varian RPM™ respiratory gating system. For each patient, 3 treatment plans were performed: a 3D-CRT and an IMRT plan, each based on the free-breathing scan, and a PGRT plan, based on the deep inspiration breath-hold scan. Dose-volume histograms were compared by means of the Friedman test.

Results

The median mean heart dose was 3 Gy (range 0.9-7.3 Gy) in the CRT plans, 1.9 Gy (range 0.5-3.6 Gy) in the PGRT plans, and 4.5 Gy (range 1.1-10.5 Gy) in the IMRT plans (p = 0.001). The mean heart V25 was 1.2% (range 0%-9.7%), 0% (range 0%-2.0%), and 0.2% (range 0%-7.3%) for CRT, PGRT, and IMRT plans, respectively (p<0.001).

Conclusions

Prospective-gating RT to the left breast offered the best protection of heart and lung, as well as a lower irradiation of the contralateral breast, compared to CRT or IMRT.