De-escalation of breast radiotherapy after conserving surgery in low-risk early breast cancer patients

Hype or hope? A review of challenges in balancing tumor control and treatment toxicity in breast cancer from the perspective of the radiation oncologist

The aim of this article is to discuss the challenges and new strategies in managing breast cancer patients, with a specific focus on radiation oncology and the importance of balancing oncologic outcomes with quality of life and post-treatment morbidity. A comprehensive literature review was conducted to identify advances in the management of breast cancer, exploring de-escalation strategies, hypofractionation schemes, predictors and tools for reducing toxicity (radiation-induced lymphocyte apoptosis, deep inspiration breath-hold, adaptive radiotherapy), enhancer treatments (hyperthermia, immunotherapy) and innovative diagnostic modalities (PET-MRI, omics). Balancing oncologic outcomes with quality of life and post-treatment morbidity is crucial in the era of personalized medicine. Radiotherapy plays a critical role in the management of breast cancer patients. Large randomized trials are necessary to generalize some practices and cost remains the main obstacle for many innovations that are already applicable.

Survival analysis of palliative radiotherapy in patients with HER-2+ metastatic breast cancer

Background

Whether radiotherapy can improve the long-term survival of HER-2+ metastatic breast cancer remains unclear. We launched this study to explore the effect of HER-2+ metastatic breast cancer patients through anti-HER-2 targeted therapy + radiotherapy.

Methods

488 HER-2 + metastatic breast cancer patients who received anti-HER2 targeted ± local radiotherapy from March 2006 to September 2021 were retrospectively collected. Patients were divided into a radiotherapy group (n=207) and a non-radiotherapy group (n=281) based on whether they received radiotherapy or not. 1: 1 propensity matching analysis was used to determine two groups of patients with similar baselines.

Results

Before matching, the radiotherapy group (n=207) had a median overall survival (mOS) of 51.7 months (48.8-63.8), which was superior to the non-radiotherapy group's (n=281) mOS of 33.9 months (27.9-39.9) (P < 0.0001). Moreover, the radiotherapy group exhibited better 1-year (94.6% vs 83.9%), 3-year (70.8% vs 45.5%), and 5-year (43.3% vs 25.0%) survival rates compared to the control group. Propensity score matching analysis identified 135 pairs of baseline-matched patients. In the matched groups, the mOS was 57.2 (44.5-69.8) months in the radiotherapy group (n=135) and 34.1 (27.5-40.6) months in the non-radiotherapy group (n=135), showing a statistically significant difference (P < 0.0001). Additionally, the radiotherapy group demonstrated 1-, 3-, and 5-year survival rates of 93.2%, 71.5%, and 46.9%, respectively, while those in the non-radiotherapy group were 89.4%, 45.8%, and 22.2%, respectively. Multivariate Cox analysis revealed that the presence of brain metastasis, liver metastasis, and radiotherapy were identified as independent predictive factors significantly associated with OS.

Conclusion

In patients with HER-2 positive metastatic breast cancer, radiotherapy was associated with better survival benefits compared to those who did not receive radiotherapy.

Integrating Tumor-Intrinsic and Immunologic Factors to Identify Immunogenic Breast Cancers from a Low-Risk Cohort: Results from the Randomized SweBCG91RT Trial

PURPOSE

The local immune infiltrate's influence on tumor progression may be closely linked to tumor-intrinsic factors. The study aimed to investigate whether integrating immunologic and tumor-intrinsic factors can identify patients from a low-risk cohort who may be candidates for radiotherapy (RT) de-escalation.

EXPERIMENTAL DESIGN

The SweBCG91RT trial included 1,178 patients with stage I to IIA breast cancer, randomized to breast-conserving surgery with or without adjuvant RT, and followed for a median of 15.2 years. We trained two models designed to capture immunologic activity and immunomodulatory tumor-intrinsic qualities, respectively. We then analyzed if combining these two variables could further stratify tumors, allowing for identifying a subgroup where RT de-escalation is feasible, despite clinical indicators of a high risk of ipsilateral breast tumor recurrence (IBTR).

RESULTS

The prognostic effect of the immunologic model could be predicted by the tumor-intrinsic model (Pinteraction = 0.01). By integrating measurements of the immunologic- and tumor-intrinsic models, patients who benefited from an active immune infiltrate could be identified. These patients benefited from standard RT (HR, 0.28; 95% CI, 0.09-0.85; P = 0.025) and had a 5.4% 10-year incidence of IBTR after irradiation despite high-risk genomic indicators and a low frequency of systemic therapy. In contrast, high-risk tumors without an immune infiltrate had a high 10-year incidence of IBTR despite RT treatment (19.5%; 95% CI, 12.2-30.3).

CONCLUSIONS

Integrating tumor-intrinsic and immunologic factors may identify immunogenic tumors in early-stage breast cancer populations dominated by ER-positive tumors. Patients who benefit from an activated immune infiltrate may be candidates for RT de-escalation.

Comparison of Efficacy and Psychology of Breast-Conserving Surgery and Modified Radical Mastectomy on Patients with Early Breast Cancer under Graded Nursing

Objective

To compare the efficacy and psychology of breast-conserving surgery and modified radical mastectomy in patients with early breast cancer (BC) under graded nursing.

Methods

Forty-one early breast-conserving surgery BC patients admitted to our hospital from April 2020 to March 2022 were regarded as group A, and 52 with modified radical surgery were seen as group B. The operating time, intraoperative bleeding, postoperative drainage, and hospital stay were compared, and the postoperative adverse effects were counted. In addition, patients' psychology and quality of life were assessed using the HAMD, HAMA, and QLSBC rating scales. At the time of discharge, a treatment satisfaction survey was conducted.

Results

The operative time, intraoperative bleeding, postoperative drainage, and hospital stay of patients in group A were lower than those in group B (P < 0.05). After treatment, the HAMD and HAMA scores were lower in group A than in group B, while the QLSBC scores and treatment satisfaction were higher (P < 0.05).

Conclusion

Breast-conserving surgery under graded nursing is less damaging to early BC patients. It can effectively shorten the postoperative recovery process and improve the psychology and quality of life, so it has higher clinical applicability.

Hypofractionation and Concomitant Boost in Ductal Carcinoma In Situ (DCIS): Analysis of a Prospective Case Series with Long-Term Follow-Up

We previously reported on a cohort of breast cancer patients affected with ductal carcinoma in situ (DCIS) that were treated with breast conservative surgery and hypofractionated whole-breast radiotherapy with a concomitant boost to the lumpectomy cavity. We now report on the long-term results of the oncological and toxicity outcomes, at a median follow-up of 11.2 years. We also include an analysis of the predictive factors for local recurrence (LR). Eighty-two patients with long-term observation were considered for this report. All received hypofractionated post-operative radiotherapy with a concomitant boost (45 Gy/20 fractions to the whole breast and 50 Gy/20 fractions to the lumpectomy cavity). We report on LC rates at 5 and 10 years, overall survival (OS), and breast-cancer-specific survival (BCSS), employing the Kaplan–Meier method. Cox proportional regression analysis was used to determine the role of selected clinical parameters on the risk of local recurrence, by the univariate and multivariate models. After a median follow-up of 11.2 years (range 5–15 years), 9 pts (11%) developed LR. The LR rates at 5 years and 10 years were 2.4% and 8.2%, respectively. The 5- and 10-year overall survival rates were 98.8% and 91.6%, respectively. The 5- and 10-year breast-cancer-specific survival rates were 100.0% and 99.0%. Late skin and subcutaneous toxicities were generally mild, and cosmetic results were good–excellent for most patients. For the univariate regression analysis, ER positive status (HR; 95% CI, p = 0.021), PgR positive status (HR; 95% CI, p = 0.012), and the aggregate data of positive hormonal status (HR; 95% CI, p = 0.021) were inversely correlated to LR risk. Conversely, a high tumor grade (G3) was directly correlated with the risk of LR (HR; 95% CI, p = 0.048). For the multivariate regression analysis, a high tumor grade (G3) confirmed its negative impact on LR (HR 0.40; 95% CI 0.19–0.75, p = 0.047). Our long-term data demonstrate hypofractionated whole-breast radiotherapy with a concomitant boost to be feasable, effective, and tolerable. Our experience suggests positive hormonal status to be protective with respect to LR risk. A high tumor grade is a risk factor for LR.

A patient decision aid for breast cancer patients deciding on their radiation treatment, no change in decisional conflict but better informed choices

BACKGROUND AND PURPOSE

In selected breast cancer patients, radiation treatment (RT) lowers the recurrence risk, with minor or no improvement of survival. In these patients, the choice to undergo RT is considered a preference-sensitive decision. To facilitate shared decision-making (SDM) for this choice, a patient decision aid was made. We aimed to evaluate the effect of the PtDA on decisional conflict.

MATERIAL AND METHODS

We performed a multi-center pre- and post-intervention study (BRASA-trial). The first 214 patients made a choice without support of the PtDA; the subsequent 189 patients received a link to the PtDA. The primary endpoint was decisional conflict; secondary endpoints were perceived SDM and knowledge on treatment options. Patients filled out questionnaires immediately after, and three months after their decision. Data were analyzed with multi-level regression analysis.

RESULTS

After correcting for the difference in age and educational level, the mean (±SD) decisional conflict for the intervention group (27.3 ± 11.4) was similar to the control group (26.8 ± 11.4; difference = 0.86, 95 %CI 1.67,3.36) three months after their decision. This also applied to perceived SDM. Patients exposed to the PtDA pursued additional treatment less often (45% vs 56%, odds ratio 0.59, 95 %CI 0.37,0.95) and scored significantly higher on the knowledge test (7.4 ± 2.5 vs 6.1 ± 2.7, corrected difference = 1.0, 95 %CI 0.50,1.49). There was no significant increase in consultation time.

CONCLUSIONS

Handing out the PtDA was not associated with improved scores in decisional conflict or perceived SDM, but it was associated with a choice for less additional treatment and better knowledge about the treatment options.

Nomogram for the personalisation of radiotherapy treatments in breast cancer patients

Introduction

Numerous prospective studies have shown that the incorporation of genomic assays into clinical practice significantly impacts the choice of adjuvant treatments for patients with early-stage breast cancer. However, the same evidence does not exist for the treatment of locoregional recurrences.

Hypothesis and objectives

The main objective of this work was to identify the clinicopathological, molecular, and genetic parameters that allow patients to be more precisely categorised into risk groups, in order to create a locoregional recurrence riskclassification tool, the PersonalRT27.

Material and methods

To create PersonalRT27, we retrospective assessed the variables of patients with early breast cancer (stages I or II) who had undergone the OncotypeDx ® and MammaPrint ® genetic tests. These variables and factors included in the tests were categorised and weighted to obtain scores between 1 and 5 pointsto represent a lower or higher risk of relapse, respectively, based on these factors and as determined by the researchers.

Results

The mean follow-up time was 60.5 months (range 25–96 months); locoregional progression-free survival at the time of the analysis was 98.4%, and overall survival was 97.5%, of which 0.6% of the deaths had been cancer specific. The area under the curve for the PersonalRT27 was 0.76 (95% CI [0.70, 0.81]), sensitivity was 78%, and the specificity was 58.9%. We used these factors to create an inhospital web-based nomogram.

Conclusions

The PersonalRT27 is a novel tool that integrates clinical-pathological, molecular, and genetic parameters. External and independent validation will be required to implement its clinical use.

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Genomic assays impact the choice of adjuvant systemic treatment for patients with early-stage breast cancer.

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However, the same evidence does not exist for decision making regarding adjuvant locoregional therapy.

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In other words, can the clinically approved genomic assays predict the risk of locoregional recurrende as a primary event.

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The main objective of this work was to identify the clinicopathological, molecular, and genetic parameters that allow patients to be more precisely categorised into risk groups, in order to create a locoregional recurrence risk-classification tool, the PersonalRT27.

Quality of Life Interventions in Breast Cancer Survivors: State of the Art in Targeted Rehabilitation Strategies

Breast cancer is the most common malignant tumor and the most prevalent cause of mortality in women. Advances in early diagnosis and more effective adjuvant therapies have improved the long-term survival of these patients. Pharmacotherapies and intrinsic tumor-related factors may lead to a wide spectrum of treatment-related disabling complications, such as breast cancer-related lymphedema, axillary web syndrome, persistent pain, bone loss, arthralgia, and fatigue. These conditions have a detrimental impact on the health-related quality of life of survivors. Here, we sought to provide a portrait of the role that rehabilitation plays in breast cancer survivors. Particular emphasis has been placed on recovering function, improving independence in activities of daily living, and reducing disability. This complex scenario requires a precision medicine approach to provide more effective decision-making and adequate treatment compliance.

Clinical Relevance of Tubular Breast Carcinoma: Large Retrospective Study and Meta-Analysis

Background: Tubular carcinoma (TC) is a low proliferative grade 1 (G1) breast cancer (BC). Despite its favorable outcome and allegedly lower aggressiveness, patients are treated like other luminal G1 BC, with radiotherapy (RT) and hormonal therapy (HT). We performed: (1) a retrospective study comparing a TC cohort and a control series of luminal G1 BC and (2) a systematic review and meta-analysis focused on TC outcome.

Materials and Methods: We selected a series of 572 G1 luminal BC patients [111 TC, 350 not otherwise specified (NOS), and 111 special-type (ST) BC] with follow-up and clinico-pathological data, who underwent local excision followed by RT at Città della Salute e della Scienza Hospital, Turin. Moreover, 22 and 13 studies were included in qualitative and quantitative meta-analysis, respectively.

Results: TCs were generally smaller (≤10 mm) (P < 0.001), with lower lymph node involvement (P < 0.001). TCs showed no local and/or distant recurrences, while 16 NOS and 2 ST relapsed (P = 0.036). Kaplan–Meier curves confirmed more favorable TC outcome (DFI: log-rank test P = 0.03). Meta-analysis data, including the results of our study, showed that the pooled DFI rate was 96.4 and 91.8% at 5 and 10 years, respectively. Meta-regression analyses did not show a significant influence of RT nor HT on the DFI at 10 years.

Conclusions: Compared to the other G1 BCs, TCs have an excellent outcome. The meta-analysis shows that TC recurrences are infrequent, and HT and RT have limited influence on prognosis. Hence, accurate diagnosis of TC subtype is critical to ensuring a tailored treatment approach.

Radiotherapy after breast-conserving surgery for elderly patients with early-stage breast cancer: A national registry-based study

Considerable controversies exist regarding whether elderly patients with early-stage breast cancer receiving breast-conserving surgery (BCS) should forgo radiotherapy. We utilized the National Cancer Database to analyze data of 115 516 women aged ≥70 years, treated with BCS for T1-2N0-1M0 breast cancer between 2004 and 2014. Multivariable Cox proportional hazards model was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for mortality 3, 5 and 10 years after 90 days of BCS associated with radiotherapy. Patients who received no radiotherapy had a higher mortality rate than those who received radiotherapy (5-year survival rate: 71.2% vs 83.8%), with multivariable-adjusted HRs of 1.65 (95% CI: 1.57-1.72) for 3-year mortality, 1.53 (1.47-1.58) for 5-year mortality and 1.43 (1.39-1.48) for 10-year mortality. The association held even for patients ≥90 years. This association was observed in all strata by reasons for radiotherapy omission, receipt of endocrine therapy or chemotherapy, calendar period and other clinical characteristics, with 40% to 65% increased 5-year mortality for patients without radiotherapy. This positive association persisted when analyses were restricted to patients with T1N0 and estrogen-receptor-positive disease who had received endocrine therapy (5-year mortality: HR 1.47 [1.39-1.57]) and in propensity score weighted analyses. Our study shows, in routine practice, elderly patients who received no post-BCS radiotherapy had higher total mortality than those who received radiotherapy. These findings suggest that the current recommendation of omission of post-BCS radiotherapy for elderly women with early-stage breast cancer may need to be reconsidered, particularly for those without contraindication.

Suggestions for Radiation Oncologists during the COVID-19 Pandemic

SARS-CoV-2 pandemic and COVID-19 diffusion have recently become an international public health emergency. Cancer patients, as a frail population, are particularly exposed to the risk related to infections. The clinical decision-making process and the organizational workflow of radiotherapy department should be revised in the light of the critical situation. We herein provide practical suggestions derived from the available literature and discussed during an online session held within the e-learning educational program of the European School of Oncology on March 31st 2020.

Older age and comorbidity in breast cancer: is RT alone the new therapeutic frontier?

AIM

To assess the impact of age, comorbidities and endocrine therapy (ET) in older breast cancer (BC) patients treated with hypofractionated radiotherapy (Hypo-RT).

METHODS

From June 2009 to December 2017, we enrolled in this study 735 ER-positive BC patients (stage pT1-T2, pNx-1, M0 and age ≥ 65 years) receiving hypo-RT and followed them until September 2019. Baseline comorbidities included in the hypertension-augmented Charlson Comorbidity Index were retrospectively retrieved. Logistic regression model estimated adjusted-odds ratios (ORs) of ET prescription in relation to baseline patient and tumor characteristics. Competing risk analysis estimated 5-year cumulative incidence function (CIF) of ET discontinuation due to side effects (with BC progression or death as competing events), and its effect on locoregional recurrence (LRR) and distant metastasis (DM) (with death as competing event).

RESULTS

ET has been prescribed in 89% patients. In multivariable analysis, the odds of ET prescription was significantly reduced in older patients (≥ 80 years, OR 0.08, 95% CI 0.03-0.20) and significantly increased in patients with moderate comorbidity. Patients ≥ 80 years discontinued the prescribed therapy earlier and more frequently than younger (65-69 years) patients (p = 0.060). Five-year CIF of LLR, DM and death from causes other that BC were 1.7%, 2.2% and 7.5%, respectively. Patients who discontinued ET had higher chance of LRR (p = 0.004). ET use did not impact on OS in any of the analyzed groups.

CONCLUSIONS

In older patients, ET did not show a benefit in terms of overall survival. Further studies focusing on tailored treatment approaches are warranted to offer the best care in terms of adjuvant treatment to these patients.

The 2018 assisi think tank meeting on breast cancer: International expert panel white paper

We report on the second Assisi Think Tank Meeting (ATTM) on breast cancer which was held under the auspices of the European Society for RadioTherapy & Oncology (ESTRO). In discussing in-depth current evidence and practice it was designed to identify grey areas in diverse forms of the disease. It aimed at addressing uncertainties and proposing future trials to improve patient care. Before the meeting, three key topics were selected: 1) primary systemic therapy, mastectomy, breast reconstruction and post-mastectomy radiation therapy, 2) therapeutic options in ductal carcinoma in situ, and 3) therapy de-escalation in early stage breast cancer. Clinical practice in these areas was investigated by means of an online questionnaire. The time lapse period between the survey and the meeting was used to review the literature and on-going clinical trials. At the ATTM both were discussed in depth and research protocols were proposed.

Accelerated Partial Breast Irradiation: A New Standard of Care?

Background

Breast-conserving therapy including lumpectomy and adjuvant whole breast irradiation (WBI) has become the standard therapy for early-stage breast cancer (EBC). Without WBI, the recurrence rate is significantly increased. However, when selecting patients at a low a priori risk of local recurrence only a small breast-cancer-specific mortality benefit, but no overall survival improvement, was detected for WBI. As most recurrences occur close to the lumpectomy cavity, accelerated partial breast irradiation (APBI) delivered exclusively to a limited volume of tissue around the initial lumpectomy site, has gained increased attention and is now discussed as an alternative to WBI for selected EBC patients.

Summary

Numerous techniques for APBI (interstitial brachytherapy, external beam-based APBI, intraoperative radiotherapy, MR-guided radiotherapy) allow treatment delivery in a shorter period of time, and radiation oncologists expect to further reduce side effects by using these new techniques, with improvements in cosmetics and quality of life. In this review, we aim to describe the existing evidence for the feasibility and effectiveness of different APBI techniques used in modern radiotherapy.

Key Messages

APBI has provided outcomes similar to WBI combined with potentially reduced toxicity. While appropriate patient selection persists to be crucial for acceptable recurrence rates, the precise definition of patients suitable for APBI remains a matter of discussion. As long-term data are often still lacking, special attention should be paid to late side effects and long-term outcomes. Decision-making on appropriate treatment techniques should take into account not only local control rates, but also the impact on the patient's quality of life.

Omission of postoperative radiation after breast conserving surgery: A progressive paradigm shift towards precision medicine

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Post-operative radiotherapy is standard after breast conservation in early breast cancer.

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To de-escalate the treatment burden, indentifying a subset at very low risk of relapse is crucial.

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Clinical and pathological factors are important, but can be integrated with genomic signatures.

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Ongoing trials will provide evidence on patients at low risk for radiotherapy omission.

Radiation therapy is a standard therapeutic option in the post-operative setting for early breast cancer patients after breast conserving surgery, providing a substantial benefit in reducing the risk of local relapse with a consequent survival gain. Nevertheless, the reduction in the burden related to treatment is becoming crucial in modern oncology for both local and systemic therapies and investigational efforts are being put forward by radiations oncologists to identify a subset of women at very low risk to be potentially omitted from post-operative irradiation after breast conservation. Clinical factors, classical pathological parameters and new predictive scores derived from gene expression and next generation sequencing techniques are being integrated in the quest toward a reliable low-risk profile for breast cancer patients. We herein provide a comprehensive overview on the topic.

The 21-gene recurrence score and effects of adjuvant radiotherapy after breast conserving surgery in early-stage breast cancer

Aim: To investigate the associations with the 21-gene recurrence score (RS) and effect of adjuvant radiotherapy (RT) for early-stage breast cancer after breast conserving surgery. Methods: We included 13,246 patients in the SEER database. Results: Patients with a higher RS were independently related to nonreceipt of RT (p < 0.001). In both the traditional and Trial Assigning Individualized Options for Treatment (TAILORx) RS cut-offs, the receipt of RT was not related to better breast cancer-specific survival in low- and high-risk RS groups, but was independently related to better breast cancer-specific survival in intermediate-risk RS group before (p = 0.029) and after (p = 0.001) propensity score matching. Conclusion: The 21-gene-RS may impact the decision-making of adjuvant RT in early-stage breast cancer after breast conserving surgery. The survival benefit of adjuvant RT may be limited to patients with intermediate-risk RS.

Is tumor bed boost necessary in patients who achieved ypCR following neoadjuvant chemotherapy and breast conserving therapy? (KROG 12-05 and 16-16)

PURPOSE

This multi-institutional study intended to investigate the effect of tumor bed boost in patients who achieved pathologic complete response (ypCR) following neoadjuvant chemotherapy (NAC) and breast-conserving therapy (BCT).

MATERIALS AND METHODS

We identified 180 patients who initially had lymph node (LN) metastasis and achieved ypCR (ypT0/isN0) following NAC and BCT from the 13 institutions of the Korean Radiation Oncology Group (KROG) 16-16 and KROG 12-05. The effect of tumor bed boost on loco-regional control (LRC), disease-free survival (DFS), and overall survival (OS) rates was analyzed.

RESULTS

In all patients, five-year LRC, DFS and OS rates were 97.5%, 95.4%, and 99.4%, respectively. Tumor bed boost was performed in 158 (87.8%) patients. Advanced N-stage (cN2-3, p = 0.036), close resection margin (p < 0.001), and sentinel lymph node biopsy (p = 0.040) were unfavorable factors for DFS. Tumor bed boost was not a significant factor for LRC, DFS, and OS.

CONCLUSIONS

This study suggests the benefit of tumor bed boost might be minimal in ypCR patients following NAC and BCT. Larger prospective studies are needed to address this issue.

Controversial issues in radiotherapy after breast-conserving surgery for early breast cancer in older patients: a systematic review

Breast cancer is the most common malignant disease among older women, and the number of new older patients per year is increasing year by year. Radiotherapy has been confirmed as an important treatment after breast conservation for the reduction of local recurrence and mortality for all patients, including node-positive cases. However, there are fewer clinical trials evaluating the toxicity and benefits of radiotherapy for older patients. Whether radiotherapy can provide substantial benefit for older patients after breast-conserving surgery is controversial. This systematic review will focus on the key aspects of this controversial issue.

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.