Journey to hypofractionation in radiotherapy for breast cancer: critical reviews for recent updates

Concurrent Versus Sequential Adjuvant Capecitabine-Based Chemoradiation in Residual Triple-Negative Breast Cancer After Neoadjuvant-Chemotherapy: A Multicenter Comparative Study

PURPOSE

Given the aggressive nature and poor prognosis of triple-negative breast cancer (TNBC), adjuvant capecitabine has been the standard therapy for residual disease after preoperative systemic therapy (PST). However, the optimal sequence of postoperative radiation therapy (RT) and capecitabine remains unclear. This study evaluated the efficacy and safety of concurrent RT and capecitabine (RT+CAP) versus sequential RT followed by capecitabine (RT→CAP) in patients with residual TNBC after PST.

METHODS AND MATERIALS

In this multicenter retrospective study, data from 491 patients treated at 14 tertiary hospitals were analyzed. The patients received either postoperative RT→CAP (n = 255) or RT+CAP (n = 236). Survival outcomes were analyzed using the Kaplan-Meier method, and multivariable Cox regression was used to adjust for potential confounders.

RESULTS

There were no significant differences in the baseline characteristics between the 2 groups. With a median follow-up of 41.8 months, the 4-year rates of disease-free survival (DFS) and overall survival (OS) were 68.8% and 82.4%, respectively. The RT+CAP group demonstrated improvements in DFS (74.6% vs 63.7%, P = .045) and OS (86.8% vs 78.3%, P = .006) compared with the RT→CAP group. Specifically, RT+CAP showed superior DFS and OS outcomes in patients with a low disease burden (ypT0-1, ypN0/axillar level I only, or Ki67 <15%). Additionally, the incidence of ≥grade 2 toxicities and discontinuation of capecitabine because of toxicity did not differ, indicating that RT+CAP was well tolerated.

CONCLUSIONS

RT+CAP offers improvements in oncologic outcomes without an increase in adverse events compared with RT→CAP, suggesting it is a promising treatment option for patients with residual TNBC after PST.

Smoking increases breast toxicity despite adjuvant hypofractionated IMRT in early breast cancer

OBJECTIVE

To evaluate the impact of smoking on acute and chronic toxicity in early breast cancer patients treated with hypofractionated intensity-modulated radiation therapy (IMRT) and a brachytherapy boost following breast-conserving surgery.

METHODS

A retrospective study of 638 patients treated between 2009 and 2017, with 566 having recorded smoking status. Acute toxicity was assessed at treatment end and chronic toxicity at least one-year post-treatment, using Common Terminology Criteria for Adverse Events v4.0. Statistical analyses included chi-square tests and relative risk (RR) calculations.

RESULTS

A total of 566 patients were included in the study, with 31.3% being smokers. The cohort was followed for a median of 6 years (range: 1-11 years). Acute toxicity was primarily characterized by radiodermatitis, with 87.6% of patients developing grade 1 and 5.5% experiencing grade 2. No cases of grade ≥ 3 were observed, and 6.9% of patients did not experience radiodermatitis. Bleeding was rare (1.1%) and infections occurred in 2.0% of patients. Regarding chronic toxicity, 67.1% of patients had no fibrosis, while 27.4% had grade 1 fibrosis. Grade 2 and grade 3 fibrosis were observed in 4.9% and 0.6% of patients, respectively, with no cases of grade 4 fibrosis. Edema was present in 8.0%, and 4.4% of patients reported chronic pain. When comparing smokers and nonsmokers, acute toxicity incidence, particularly radiodermatitis, was similar between the two groups. Smokers had a significantly higher incidence of chronic fibrosis (35.6% vs. 24.7%, p = 0.013) and chronic pain (7.9% vs. 3.3%, p = 0.024) compared to nonsmokers. However, there were no significant differences in the occurrence of edema between smokers and nonsmokers (7.9% vs. 8.0%, p = 0.879).

CONCLUSION

While advanced radiation techniques such as hypofractionated IMRT improve overall toxicity profiles, smoking significantly exacerbates chronic toxicity in breast cancer patients. This study underscores the urgent need for comprehensive smoking cessation programs as part of cancer care, addressing lifestyle factors to improve patient outcomes and quality of life.

The Effect of Ionising Radiation on the Properties of Tumour-Derived Exosomes and Their Ability to Modify the Biology of Non-Irradiated Breast Cancer Cells-An In Vitro Study

The vast majority of breast cancer patients require radiotherapy but some of them will develop local recurrences and potentially metastases in the future. Recent data show that exosomal cargo is essential in these processes. Thus, we investigated the influence of ionising radiation on exosome properties and their ability to modify the sensitivity and biology of non-irradiated cells. Exosomes were isolated from breast cancer cell lines (MDA-MB-231, MCF7, and SKBR3) irradiated with 2 Gy (Exo 2 Gy) or no irradiation (Exo 0 Gy). Despite some differences in their molecular profiles, they did not affect cell viability, proliferation, cell cycle phase distribution, and radioresistance; however, both populations showed the ability to modify cell migration and invasion potential, as confirmed by the downregulation of β-catenin, which is responsible for maintaining the epithelial phenotype. Interestingly, exosomes from irradiated BCa cells were more actively deposited in the endothelial cells (EA.hy926). Furthermore, exosomes tend to lower the expression of CD31, which is responsible for maintaining intact vascularity. This preliminary study demonstrates the vital role of exosomes and their altered profile due to irradiation in the pathobiology of breast cancer.

An observational study comparing the dosimetry and clinical effects of conventional versus hypofractionated radiotherapy in elderly patients of early breast cancer

INTRODUCTION

Hypofractionated radiation therapy after Breast Conserving Surgery in patients of early breast carcinoma results in equivalent clinical outcome but better cosmesis as compared to conventional therapy. In this study we have compared the dosimetry and clinical outcome between Hypofractionated and Conventional whole breast radiation followed by boost therapy after patients had undergone breast conserving surgery for early breast cancer.

AIMS AND OBJECTIVES

1. Dosimetric analysis and toxicity assessment between conventional and Hypofractionated radiation therapy.2. Comparative analysis of late toxicity between two groups.

MATERIALS AND METHODS

In the department of Radiation Oncology in a Tertiary Care Hospital, 100 patients between the age group 65-75 years were selected as per inclusion criteria of the study and there were 60 patients in the conventional group and 40 in the hypofractionated group respectively. All the patients underwent treatment in Varian Truebeam Linear accelerator with appropriate radiation planning after undergoing Breast Conserving Surgery along with adjuvant chemotherapy when indicated.The conventional group received a dose of 50 Gy in 25# followed by boost of 10 Gy in 5 # and the hypofractionated arm received a dose of 42.5Gy in 16# followed by a boost of 12.5Gy in 5 # . The post-operative tumour cavity was irradiated along with axillary lymph nodes when indicated. All the patients in both arms were assessed for toxicity related to therapy and quality of life as per EORTC Q45 in 2 years following treatment completion. All statistical tests were done by SPSS version 23. Unpaired t-test was used for dosimetric comparison. Comparison of QOL and toxicity was done by Chi-square test respectively between two groups. A p-value of < 0.05 was taken to be significant.

RESULTS

At the end of 2 years, 54 patients in conventional group and 38 patients in hypofractionated group could be assessed respectively and rest in both groups had lost to follow-up due to logistical reasons. There was no significant difference in dosimetry between the two groups as per unpaired t-test (P value >0.05). In terms of Quality of Life assessment in two years following the completion of therapy the conventional arm had more toxicity than hypofractionated arm as per Chi-square test (P value <0.05). Chi-square test revealed patients who had conventional therapy had worse cosmetic outcome and increased incidence of myelotoxicity than in those who received hypofractionated therapy, both statistically significant (P value < 0.05). There was no incidence of locoregional relapse in either groups.

CONCLUSION

Hypofractionated whole breast Radiation therapy followed by boost therapy with can result in less toxicity and thus better cosmetic outcome and almost equal dosimetric results compared to Conventional Radiotherapy in patients after breast conserving surgery, thus comparatively increasing their quality of life.

Understanding the risk of ionizing radiation in breast imaging: Concepts and quantities, clinical importance, and future directions

BACKGROUND

Conventional mammography remains the primary imaging modality for state-of-the-art breast imaging practice and its benefit (both on diagnostic and screening) was largely reported. In mammography, the typical Mean Glandular Dose (MGD) from X-ray radiation to the breast spans, on average, from 1 to 10 mGy, depending on breast thicknesses, percentage of fibroglandular tissue, and on the examination purpose.

METHODS

The aim of this narrative review is to describe the extent of radiation risk in X-ray breast imaging and discuss the main steps and parameters (e.g. MGD, screening frequency and number of examination views) that may have an influence on the radiation risk assessment.

RESULTS

Even though the radiation doses used with these examinations are very low, as compared to other medical or natural radiation exposures, there is a non-negligible associated risk of radiation-induced cancer. Accurate radiation risk assessment permits to better balance the overall estimation of the benefit-to-risk ratio in X-ray breast imaging.

CONCLUSIONS

It is expected that a better knowledge about radiation-induced cancer risk among population could improve the communications skills between patients and clinicians and could help to increase the awareness in women about radiation risk perception for a transparent and proper informed choice of imaging exam.

Advantages of single high-dose radiation therapy compared with conventional fractionated radiation therapy in overcoming radioresistance

BACKGROUND

Radioresistance is a major clinical challenge in cancer treatment, as it reduces the effectiveness of radiation therapy (RT). While advances in radiation delivery have enabled the clinical use of high-dose hypofractionated RT, its impact on radioresistant tumors remains unclear. This study aimed to compare the effects of single high-dose RT with conventional fractionated RT on radioresistant breast cancer cells and explore the underlying mechanisms.

METHODS

Radioresistant cell lines were previously established by exposing SK-BR-3 and MCF-7 cells to 48 Gy and 70 Gy of radiation, respectively, in multiple fractions. We compared the effects of 2 Gy × 5 and 7 Gy × 1 fractions on these cells using clonogenic survival assays and western blot analysis. In vivo antitumor effects were assessed in SR tumor-bearing BALB/c mice irradiated with either 2 Gy × 5 or 7 Gy × 1 fractions.

RESULTS

7 Gy x1 was more efficient at killing radioresistant breast cancer cells than 2 Gy x5. Furthermore, the 7 Gy x1 fraction produced higher levels of reactive oxygen species (ROS) and decreased the expression of radioresistance factors such as p-STAT3, ACSL4, FOXM1, RAD51, Bcl-xL, and survivin. Consistent with the in vitro studies, the 7 Gy × 1 fraction also showed superior antitumor effects in SR tumor-bearing BALB/c mice.

CONCLUSIONS

Single high-dose RT offers superior advantages over conventional fractionated RT in regard to overcoming radioresistance, supporting its potential as a promising treatment for recurrent tumors.

Outcomes of whole breast radiation therapy in Asian breast cancer patients with prior cosmetic implants

BACKGROUND

As breast augmentation has become more popular, an increasing number of women with augmented breasts require treatment for breast cancer. This study aimed to assess the outcomes of postoperative whole breast radiation therapy (WB-RT) in Asian patients with breast cancer who underwent prior cosmetic breast implantation.

METHODS

We retrospectively reviewed the medical records of 61 patients with breast cancer who had prior cosmetic breast implants (prior-CBI) and underwent breast-conserving surgery (BCS) and WB-RT between 2015 and 2020. The median implant volume was 238.8 cc, with a median interval of 84.7 months between the prior-CBI and BCS. WB-RT was administered with either conventional fractionation (CF-RT) at 50 Gy in 25 fractions (N = 36) or hypofractionation (HF-RT) at 42.6 Gy in 16 fractions (N = 25). The incidences of implant-related complications (IRC) and their contributing factors were analyzed.

RESULTS

After a median follow-up of 43.5 months, the 3-year cumulative incidences of IRC and implant loss were 17.2% and 4.9%, respectively. Among the four (6.6%) patients who opted for implant removal after RT, three were potentially related to RT-related capsular contracture. There was no difference in the 3-year cumulative IRC rates following CF-RT and HF-RT (12.2% and 26.7%, respectively; p = 0.120). The risk factors for IRC included a larger implant size (> 260 cc) and a higher ratio of breast tissue to implant volume.

CONCLUSIONS

This study demonstrated a favorable safety profile of WB-RT for treatment of breast cancer in Asian women with prior-CBI. The integration of HF-RT following BCS was thought to be a feasible approach.

An IMRT planning technique for treating whole breast or chest wall with regional lymph nodes on Halcyon and Ethos

PURPOSE/OBJECTIVE

Field size limitations on Halcyon and Ethos treatment machines largely preclude use of the conventional monoisocentric three-field technique for breast/chest wall and regional lymph nodes. We present an alternative, IMRT-based planning approach that facilitates treatment on Halcyon and Ethos while preserving plan quality.

MATERIALS/METHODS

Eight breast and regional node cases (four left-sided, four right-sided) were planned for an Ethos machine using a 15-17 field IMRT technique. Institutional plan quality metrics for CTV and PTV coverage and OAR sparing were assessed. Five plans (four right-sided, one left-sided) were also planned using a hybrid 3D multisocenter technique. CTV coverage and OAR sparing were compared to the IMRT plans. Eclipse scripting tools were developed to aid in beam placement and plan evaluation through a set of dosimetric scorecards, and both are shared publicly.

RESULTS

On average, the IMRT plans achieved breast CTV and PTV coverage at 50 Gy of 97.9% and 95.7%, respectively. Supraclavicular CTV and PTV coverages at 45 Gy were 100% and 95.5%. Axillary lymph node CTV and PTV coverages at 45 Gy were 100% and 97.1%, and IMN CTV coverage at 45 Gy was 99.2%. Mean ipsilateral lung V20 Gy was 19.3%, and average mean heart dose was 1.6 Gy for right-sided cases and 3.0 Gy for left-sided. In comparison to the hybrid 3D plans, IMRT plans achieved higher breast and supraclavicular CTV coverage (99.9% vs. 98.6% and 99.9% vs. 93.4%), higher IMN coverage (99.6% vs. 78.2%), and lower ipsilateral lung V20 Gy (19.6% vs. 28.2%).

CONCLUSION

Institutional plan quality benchmarks were achieved for all eight cases using the IMRT-based planning approach. The IMRT-based planning approach offered superior conformity and OAR sparing than a competing hybrid 3D approach.

Immunotherapy and Radiation Therapy Sequencing in Breast Cancer: A Systematic Review

PURPOSE

In the past decade, immune checkpoint inhibitors (ICIs) have emerged as a treatment option for metastatic breast cancer (BC). More recently, ICIs have been approved in the perioperative setting. This has led to clinical scenarios where radiation therapy (RT) is given concurrently with ICIs. On the other hand, moderate and ultrahypofractionated schedules of RT are being widely adopted in the adjuvant setting, in addition to an increased use of metastasis-directed therapy. Furthermore, RT can modulate the tumor microenvironment and induce a systemic response at nonirradiated sites, an "abscopal effect." The amplification of antitumor immune response is used as the rationale behind the concomitant use of ICIs and RT. To date, there is a lack of literature on the optimal sequence, timing, dose/fractionation schema, and treated RT volumes with ICIs in patients with BC, especially in the era of ultrahypofractionation.

METHODS AND MATERIALS

We conducted a systematic review to delineate the reported treatment details, safety, and efficacy of combining ICI and RT in patients with BC. PubMed, Embase, and Cochrane CENTRAL were searched between 2014 and 2023. Data were extracted to assess the details of ICIs/RT delivery, safety, and efficacy.

RESULTS

Of the 12 eligible studies, 9 involved patients with metastatic BC. Most studies were phase 1/2, had a small sample size (range, 8-28), and were heterogenous in patient population and reported outcomes. The combination was reported to be safe. We identified 1 study in the perioperative setting, which did a posthoc analysis of safety/efficacy of ICIs in the adjuvant setting with receipt and pattern of RT.

CONCLUSIONS

In conclusion, there are limited data on the dose, timing, fractionation, and volumes of RT in both the adjuvant and metastatic setting in BC. Ongoing/future trials should collect and report such data on RT details, whenever RT is used in combination with ICIs.

Optimizing Clinical Implementation of Hypofractionation: Comprehensive Evidence Synthesis and Practical Guidelines for Low- and Middle-Income Settings

The global cancer burden, especially in low- and middle-income countries (LMICs), worsens existing disparities, amplified by the rising costs of advanced treatments. The shortage of radiation therapy (RT) services is a significant issue in LMICs. Extended conventional treatment regimens pose significant challenges, especially in resource-limited settings. Hypofractionated radiotherapy (HRT) and ultra-hypofractionated/stereotactic body radiation therapy (SBRT) offer promising alternatives by shortening treatment durations. This approach optimizes the utilization of radiotherapy machines, making them more effective in meeting the growing demand for cancer care. Adopting HRT/SBRT holds significant potential, especially in LMICs. This review provides the latest clinical evidence and guideline recommendations for the application of HRT/SBRT in the treatment of breast, prostate, and lung cancers. It emphasizes the critical importance of rigorous training, technology, stringent quality assurance, and safety protocols to ensure precise and secure treatments. Additionally, it addresses practical considerations for implementing these treatments in LMICs, highlighting the need for comprehensive support and collaboration to enhance patient access to advanced cancer care.

A novel, multi-active emollient for the prevention of acute radiation dermatitis in breast cancer patients: a randomized clinical trial

PURPOSE

To investigate the efficacy of a novel, multi-active emollient in preventing and managing acute radiation dermatitis (ARD) in breast cancer patients undergoing moderate hypofractionated (HF) radiotherapy (RT) compared to standard of care.

METHODSA

A monocentric, open-label, randomized clinical trial (RCT) with breast cancer patients receiving moderate HF (dose: 40.05-55.86 Gy, fractions: 15-21) was conducted between January 2022 and May 2023. The experimental group received the novel emollient, while the control group received the standard skin care. Patients applied the skin care products twice daily during the complete RT course. The primary outcome was the severity of ARD at the final RT session measured by the modified Radiation Therapy Oncology Group (RTOG) criteria. Secondary outcomes included patient symptoms, quality of life (QoL), and treatment satisfaction.

RESULTS

A total of 100 patients with 50 patients per group were enrolled. In the control group, 50% of the patients developed RTOG grade 1 ARD and 48% grade 2 or higher, while in the experimental group, the severity of ARD was significantly lower with 82% grade 1 and 16% grade 2 ARD (P = .013, χ2-test). The frequency and severity of xerosis were significantly lower in the experimental compared to the control group (Ps ≤ .036, Mann Whiney U test). The impact of ARD on the QoL was low, and treatment satisfaction was high in both groups, with no significant difference.

CONCLUSION

This RCT shows that the novel, multi-active emollient significantly reduced the ARD RTOG grade. Research in a more diverse patient population is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04929808 (11/06/2021).