Omission of Radiotherapy After Breast-Conserving Surgery for Women With Breast Cancer With Low Clinical and Genomic Risk: 5-Year Outcomes of IDEA

Navigating through recent evidence on locoregional breast cancer radiotherapy: an initiative by the scientific association of Swiss radiation oncology

PURPOSE

Breast cancer (BC) is the most prevalent cancer in women and radiotherapy (RT) is an integral part of its treatment. High-level evidence guides clinical decisions, but given the abundance of guidelines, a need to navigate within the evidence has been identified by the board of the Scientific Association of Swiss Radiation Oncology (SASRO). A pilot project was initiated aiming to create an overview of recent clinically relevant evidence for BC RT, to make it easily available to (radiation) oncologists and radiation oncologists in training.

METHODS

A panel of 10 radiation oncology experts for BC RT, one expert in BC surgery, and one expert in BC medical oncology critically reviewed the relevant literature. The panel comprehensively represented different geographical regions of Switzerland as well as university, cantonal, and private institutions. We sought to create a consensual overview of the most relevant questions in BC RT today, accompanied by the most recent and relevant available evidence.

RESULTS

From January 2023 to January 2024, the panel met four times to review and work on an initial draft. The final draft was reviewed and accepted by all panelists. We hereby publish this work to make it available to international audiences. After publication, the work will be made available to all SASRO members on the SASRO website. This work is to be updated every 2 years.

CONCLUSION

The identified need was addressed with a successful pilot project and will be further expanded upon in other tumor pathologies.

Biomarker-Directed Radiotherapy in Breast Cancer: A Narrative Review

Importance

Integration of molecular biomarker information into systemic therapy has become standard practice in breast cancer care. However, its implementation in guiding radiotherapy (RT) is slower. Although postoperative RT is recommended for most patients after breast-conserving surgery and, depending on risk factors, following mastectomy, emerging evidence has indicated that patients with low scores on gene expression signatures or selected clinical-pathological features may have very low local recurrence rates. This narrative review explored the potential of biomarker-directed personalized RT approaches, which may optimize treatment strategies and be associated with improved patient outcomes and experiences.

Observations

Distinctions between prognostic and predictive biomarkers were highlighted, emphasizing the importance of analytical and clinical validity in biomarker-based studies. Findings from studies investigating the prognostic and predictive value of various genomic signatures and immunohistochemical markers for guiding breast RT were presented. These included the Adjuvant Radiotherapy Intensification Classifier and the Profile for the Omission of Local Adjuvant Radiation, which have shown potential in predicting RT benefits. The genomic-adjusted radiation dose and role of tumor-infiltrating lymphocytes were also discussed. Ongoing clinical trials exploring the use of biomarkers in ductal carcinoma in situ and invasive breast cancer to refine RT decision-making were illustrated.

Conclusions and Relevance

The results of this narrative review suggest that evidence-based shared decision-making is crucial to optimize treatment according to the individual's predicted benefits and risks along with their personal preferences. Incorporation of biomarker-directed approaches in RT for breast cancer may hold promise for personalized treatment, potentially facilitating omission of RT for patients at low risk of recurrence, while identifying those who may benefit from intensified therapy. This personalized RT approach may be associated with improved clinical outcomes and quality of life and facilitate decision-making for people with breast cancer. However, there remains a need for robust clinical and analytical validation of biomarkers to ensure reliability and clinical utility for RT optimization.

Patients with DCIS Seen at a Specialized High-Risk Breast Clinic Run by Surgical Advanced Practice Providers Have High Rates of Preventive Medication Uptake

BACKGROUND

Preventative medication (PM) uptake is low among patients at an elevated risk of breast cancer, largely due to fears of intolerance. This study aimed to investigate whether a new, surgical advanced practice provider (APP)-run clinic was effectively prescribing PM. We hypothesized equivalent rates of PM uptake compared to consultation with medical oncologists (MD).

PATIENTS AND METHODS

The APP-run clinic and accompanying database were initiated 01/2023, including patients with benign breast complaints and/or an elevated risk of invasive breast cancer. A historic single-institution surgical database and this prospective database were queried for patients with ductal carcinoma in situ between 04/2007-05/2023 and 01/2023-01/2024, respectively. Patients with invasive breast cancer within the prior 5 years were excluded. Chart review abstracted PM type/dose. Chi square analysis compared PM uptake rates and dose.

RESULTS

A total of 523 patients met study criteria; the MD sample and APP sample were relatively well balanced except fewer hormone receptor positive patients in the MD sample (266/309 [86.1%] versus 202/214 [94.4%] APP, p < 0.01). PM uptake was lower in the MD sample (96/309 [31.1%] compared to the APP sample (86/214 [40.2%], p = 0.03). There was significantly more tamoxifen prescribed among the APP sample (58.2% vs. 35.6% among MD, p = 0.02), and low-dose tamoxifen prescribing increased significantly (47.3% vs. 9.8% MD, p < 0.01).

CONCLUSIONS

Our surgical APP-run breast health clinic has demonstrated equivalent PM uptake as compared to patients seen previously by medical oncologists. This model should be considered broadly. Additionally, low-dose tamoxifen has become the prescription of choice; thus, long-term studies of tamoxifen 5 mg are warranted.

Top advances of the year: Breast cancer

In this review, top updates over the past year in caring for patients with breast cancer are discussed. These include both local management as well as systemic therapy.

"When Less is More": Paradigm Shifts in Radiation Treatment for Early-Stage Breast Cancer

OPINION STATEMENT

Recent advancements in the treatment of early-stage breast cancer have significantly shifted the radiotherapy landscape. Traditionally, the standard of care included lumpectomy followed by endocrine therapy and 3-5 weeks of adjuvant radiation targeting the entire unilateral breast. This review summaries modern trials, emphasizing data reported since 2019 that have changed radiation treatment paradigms. Ultra-hypofractionated treatment regimens have enabled radiation oncologists to deliver the total radiation dose in as few as 5 treatments over 1 week for select patients. Partial breast irradiation, treating only the breast tissue nearest to the lumpectomy cavity, has also emerged as an effective and well-tolerated treatment. Furthermore, a growing body of evidence supports the safety of omitting radiation completely for certain older adults with low-risk disease. Ongoing research in areas such as precision cancer care, treatment de-escalation, and toxicity prevention and management reflects a broader shift toward shared decision-making in medicine and individually tailored treatment paradigms. As research progresses, treatment options will continue to evolve. Advances in radiation oncology will give the oncology team a growing array of tools to custom treatment plans to individual patient risks and toxicity concerns. Knowledge of radiation advances should be used to facilitate shared decisions with patients about the balance of treatment efficacy, toxicity, and quality of life, with the ultimate goal of promoting high-quality, personalized, and patient-centered cancer care.

21-gene recurrence score predictive of the benefit of postoperative radiotherapy after breast-conserving surgery for elderly patients with T1N0 and luminal breast cancer

PURPOSE

To assess the predictive value of the 21-gene recurrence score (RS) on the survival outcomes of postoperative radiotherapy (PORT) in elderly patients with T1N0 luminal breast cancer after breast-conserving surgery.

METHODS

We retrospectively included patients aged ≥ 70 years and diagnosed with T1N0 luminal BC between 2004 and 2015 using the data from the Surveillance, Epidemiology, and End Results. The RS groups were categorized using the TAILORx criteria as follows: low risk (RS < 11) (LR), intermediate risk (RS 11-25) (IR), and high risk (RS > 25) (HR). Kaplan-Meier analysis, propensity score matching (PSM), and Cox proportional hazards analysis were used for statistical analysis.

RESULTS

We included 5901 patients in the analysis. Of the patients, 4492 (76.1%) underwent PORT, while 1409 (23.9%) did not receive PORT. There were 1588 (26.9%), 3613 (61.2%), and 700 (12.0%) patients classified as LR, IR, and HR, respectively. There were 1182 (74.4%), 2773 (76.8%), and 537 (76.7%) patients in the LR, IR, and HR groups receiving PORT, respectively (P = 0.182). A total of 1353 pairs of patients were completely matched using PSM. PORT was independently associated with better overall survival (OS) (P < 0.001) and breast cancer-specific survival (BCSS) (P = 0.015) in the entire cohort. The sensitivity analyses showed that the receipt of PORT was not associated with OS (P = 0.887) and BCSS (P = 0.861) in the LR group. However, the receipt of PORT was associated with OS (P < 0.001) and BCSS in the IRHR group (P = 0.026).

CONCLUSION

Our study highlights the possible role of the 21-gene RS in predicting the survival outcomes of PORT following BCS in elderly patients with T1N0 luminal breast cancer.

Re-Evaluating the Omission of Radiation Therapy in Low-Risk Patients With Early-Stage Breast Cancer

Traditionally, management of early-stage breast cancer has required adjuvant radiation therapy following breast conserving surgery, due to decreased local recurrence and breast cancer mortality. However, over the past decade, there has been an increasing emphasis on potential overtreatment of patients with early-stage breast cancer. This has given rise to questions of how to optimize deintensification of treatment in this cohort of patients while maintaining clinical outcomes. A multitude of studies have focused on identification of a subset of patients with invasive breast cancer who were at low risk of local recurrence based on clinicopathologic features and therefore suitable for RT omission. These studies have failed to identify a subset that does not from RT with respect to local control. Several ongoing trials are evaluating alternative approaches to deintensification while focusing on tumor biology. With regards to ductal carcinoma in situ (DCIS), the role of RT has been questioned since breast conservation was utilized. Paralleling invasive disease studies, studies have sought to use clinicopathologic features to identify low risk patients suitable for RT omission but have failed to identify a subset that does not from RT with respect to local control. Use of new assays in patients with DCIS may represent the ideal approach for risk stratification and appropriate deintensification. At this time, when considering deintensification, individualizing treatment decisions with a focus on shared decision making is paramount.

Escalation and De-Escalation of Adjuvant Radiotherapy in Early Breast Cancer: Strategies for Risk-Adapted Optimization

Postoperative radiotherapy (RT) is recommended after breast-conserving surgery and mastectomy (with risk factors). Consideration of pros and cons, including potential side effects, demands the optimization of adjuvant RT and a risk-adapted approach. There is clear de-escalation in fractionation-hypofractionation should be considered standard. For selected low-risk situations, PBI only or even the omission of RT might be appropriate. In contrast, tendencies toward escalating RT are obvious. Preoperative RT seems attractive for patients in whom breast reconstruction is planned or for defining the tumor location more precisely with the potential of giving ablative doses. Dose escalation by a (simultaneous integrated) boost or the combination with new compounds/systemic treatments may increase antitumor efficacy but also toxicity. Despite low evidence, RT for oligometastatic disease is becoming increasingly popular. The omission of axillary dissection in node-positive disease led to an escalation of regional RT. Studies are ongoing to test if any axillary treatment can be omitted and which oligometastatic patients do really benefit from RT. Besides technical improvements, the incorporation of molecular risk profiles and also the response to neoadjuvant systemic therapy have the potential to optimize the decision-making concerning if and how local and/or regional RT should be administered.

Ultrahypofractionation in postoperative radiotherapy for breast cancer: A single-institution retrospective cohort series

BACKGROUND

The 'FAST-forward', study published in April 2020, demonstrated the effectiveness of an extremely hypofractionated radiotherapy schedule, delivering the total radiation dose in five sessions over the course of 1 week. We share our department's experience regarding patients treated with this regimen in real-world clinical settings, detailing outcomes related to short-term toxicity and efficacy.

METHODS

A descriptive observational study was conducted on 160 patients diagnosed with breast cancer. Between July 2020 and December 2021, patients underwent conservative surgery followed by a regimen of 26 Gy administered in five daily fractions.

RESULTS

The median age was 64 years (range: 43-83), with 82 patients (51.3%) treated for left-sided breast cancer, 77 patients (48.1%) for right-sided breast cancer, and 1 instance (0.6%) of bilateral breast cancer. Of these, 66 patients had pT1c (41.3%), 70.6% were infiltrative ductal carcinomas, and 11.3% were ductal carcinoma in situ. Most tumours exhibited intermediate grade (41.9%), were hormone receptor positive (81.3%), had low Ki-67 (Ki-67 < 20%; 51.9%) and were Her 2 negative (85%). The majority of surgical margins were negative (99.4%). Among the patients, 72.5% received hormonotherapy, and 23.8% received chemotherapy. Additionally, 26 patients (16.3%) received an additional tumour boost following whole breast irradiation (WHBI) of 10 Gy administered in five sessions of 2 Gy over a week. The median planning target volume (PTV) was 899 cm3 (range: 110-2509 cm3). Early toxicity was primarily grade I radiodermatitis, affecting 117 patients (73.1%). During a median follow-up of 15 months (range: 3.9-28.77), only one patient experienced a local relapse, which required mastectomy.

CONCLUSIONS

The implementation of this highly hypofractionated regimen in early-stage breast cancer appears feasible and demonstrates minimal early toxicity. However, a more extended follow-up duration would be required to evaluate long-term toxicity and efficacy accurately.

Natural Guardians: Natural Compounds as Radioprotectors in Cancer Therapy

Cancer remains a significant global health challenge, with millions of deaths attributed to it annually. Radiotherapy, a cornerstone in cancer treatment, aims to destroy cancer cells while minimizing harm to healthy tissues. However, the harmful effects of irradiation on normal cells present a formidable obstacle. To mitigate these effects, researchers have explored using radioprotectors and mitigators, including natural compounds derived from secondary plant metabolites. This review outlines the diverse classes of natural compounds, elucidating their roles as protectants of healthy cells. Furthermore, the review highlights the potential of these compounds as radioprotective agents capable of enhancing the body's resilience to radiation therapy. By integrating natural radioprotectors into cancer treatment regimens, clinicians may improve therapeutic outcomes while minimizing the adverse effects on healthy tissues. Ongoing research in this area holds promise for developing complementary strategies to optimize radiotherapy efficacy and enhance patient quality of life.

Is my patient an appropriate candidate for sentinel node biopsy? Less axillary surgery, for the right patients. Critical review and grades of recommendation

INTRODUCTION

While general conclusions of historical trials are widely recognized, the nuances regarding precise indications of Sentinel Node Biopsy (SNB) in breast cancer in complex clinical scenarios often remain a source of debate and require further elucidation.

METHODS

Two reviewers (JFB and GNM) independently searched electronic databases for studies including SNB as the main intervention. Filters were applied to retrieve only clinical trials (randomized or experimental non-randomized); non-oncological outcomes were excluded. The selected studies were considered to construct a narrative review focused on inclusion criteria and survival outcomes, followed by recommendations.

RESULTS

Fourteen (n = 14) trials were selected, including eleven (n = 11) randomized trials for upfront surgery, and three (n = 3) single-group clinical trials for surgery following neoadjuvant therapy. All trials for upfront surgery provided long-term survival data for SNB, that was equivalent or non-inferior to axillary dissection, in tumors without palpable adenopathy (caution for larger T3 and T4 tumors) - Grade of recommendation: A. In tumors up to 5 cm, complete axillary dissection is not necessary if up to two sentinel nodes are positive for macrometastasis, and radiation therapy is planned - Grade of recommendation: A. If there are more than two sentinel nodes positive for macrometastasis, or a positive node other than the sentinel one, complete axillary dissection is recommended - Grade of recommendation: A. Following neoadjuvant chemotherapy, considering 10% as an acceptable false negative rate, SNB might be offered for cN0 patients who have remained negative, and for cN1 (caution for cN2) patients become clinically negative; complete axillary dissection might not be necessary if at least two sentinel lymph nodes are retrieved, and there is no residual disease - Grade of recommendation: B.

CONCLUSION

SNB can be performed in most cases of clinically negative nodes. After neoadjuvant chemotherapy, SNB is feasible and may have acceptable performance for cN0 and cN1 tumors, although prospective survival data is still awaited.

Personalizing Locoregional Therapy in Patients With Breast Cancer in 2024: Tailoring Axillary Surgery, Escalating Lymphatic Surgery, and Implementing Evidence-Based Hypofractionated Radiotherapy

The management of axillary lymph nodes in breast cancer is continually evolving. Recent data now support omitting axillary lymph node dissection (ALND) in most patients with metastases in up to two sentinel lymph nodes (SLNs) during upfront surgery and those with residual isolated tumor cells after neoadjuvant chemotherapy (NACT). In the upfront surgery setting, ALND is still indicated, however, in patients with clinically node-positive breast cancer or more than two positive SLNs and, after NACT, in case of residual micrometastases and macrometastases. Omission of the sentinel lymph node biopsy (SLNB) can be considered in many postmenopausal patients with small luminal breast cancer, particularly when axillary ultrasound is negative. Several randomized controlled trials (RCTs) are currently aiming at eliminating the remaining indications for ALND and also establishing omission of SLNB in a broader patient population. The movement to deescalate axillary staging is in part because of the association between ALND and lymphedema, which is swelling of an extremity because of lymphatic damage and obstructed lymphatic drainage. To reduce the risk of developing this condition, patients undergoing ALND can undergo reverse mapping of the axilla and immediate reconstruction or bypass of the lymphatics from the involved extremity. Decongestion and compression are the foundation of conservative treatment for established lymphedema, while lymphovenous bypass and lymph node transfer are surgical procedures to address the physiologic dysfunction. Radiotherapy is an essential component of breast locoregional therapy: more than three decades of radiation research has optimized treatment according to patient's risk of local recurrence while substantially reducing the number of treatment visits. High-quality RCTs have shown the efficacy and safety of hypofractionation-more than 2Gy radiation dose per treatment (fraction)-significantly reducing the burden of radiotherapy treatment for many patients with breast cancer. In 2024, guidelines recommend no more than 15-16 fractions for whole-breast and nodal radiotherapy, with some recommending five fractions for whole-breast radiotherapy. In addition, simultaneous integrated boost (SIB) has been shown to be noninferior to sequential boost with regards to ipsilateral breast tumor recurrence with similar or reduced long-term side effects, also reducing overall treatment length. Further RCTs are underway investigating other indications for five fractions, including SIB and regional node irradiation, such that, in future, it may be possible for the majority of breast radiotherapy patients to be treated with a 1-week course. This manuscript serves to outline the latest updates on axillary surgical staging, lymphatic surgery, and evidence-based radiotherapy in the treatment of breast cancer.

Avoiding Locoregional Overtreatment in Older Adults With Early-Stage Breast Cancer

Advances in the treatment of older women with early-stage breast cancer, particularly opportunities for de-escalation of therapy, have afforded patients and providers opportunity to individualize care. As the majority of women ≥65 have estrogen receptor-positive, HER2-negative disease, locoregional therapy (surgery and/or radiation) may be tailored based on a patient's physiologic age to avoid either over- or undertreatment. To determine who would derive benefit from more or less intensive therapy, an accurate assessment of an older patient's physiologic age and incorporation of patient-specific values are paramount. While there now exist well-validated geriatric assessment tools whose use is encouraged by the American Society of Clinical Oncology when considering systemic therapy, these instruments have not been widely integrated into the locoregional breast cancer care model. This review aims to highlight the importance of assessing frailty and the concepts of and over- and undertreatment, in the context of trial data supporting opportunities for safe deescalation of locoregional therapy, when treating older women with early-stage breast cancer.

Clinical Biomarkers of Tumour Radiosensitivity and Predicting Benefit from Radiotherapy: A Systematic Review

Modern advanced radiotherapy techniques have improved the precision and accuracy of radiotherapy delivery, with resulting plans being highly personalised based on individual anatomy. Adaptation for individual tumour biology remains elusive. There is an unmet need for biomarkers of intrinsic radiosensitivity that can predict tumour response to radiation to facilitate individualised decision-making, dosing and treatment planning. Over the last few decades, the use of high throughput molecular biology technologies has led to an explosion of newly discovered cancer biomarkers. Gene expression signatures are now used routinely in clinic to aid decision-making regarding adjuvant systemic therapy. They have great potential as radiotherapy biomarkers. A previous systematic review published in 2015 reported only five studies of signatures evaluated for their ability to predict radiotherapy benefits in clinical cohorts. This updated systematic review encompasses the expanded number of studies reported in the last decade. An additional 27 studies were identified. In total, 22 distinct signatures were recognised (5 pre-2015, 17 post-2015). Seventeen signatures were 'radiosensitivity' signatures and five were breast cancer prognostic signatures aiming to identify patients at an increased risk of local recurrence and therefore were more likely to benefit from adjuvant radiation. Most signatures (15/22) had not progressed beyond the discovery phase of development, with no suitable validated clinical-grade assay for application. Very few signatures (4/17 'radiosensitivity' signatures) had undergone any laboratory-based biological validation of their ability to predict tumour radiosensitivity. No signatures have been assessed prospectively in a phase III biomarker-led trial to date and none are recommended for routine use in clinical guidelines. A phase III prospective evaluation is ongoing for two breast cancer prognostic signatures. The most promising radiosensitivity signature remains the radiosensitivity index (RSI), which is used to calculate a genomic adjusted radiation dose (GARD). There is an ongoing phase II prospective biomarker-led study of RSI/GARD in triple negative breast cancer. The results of these trials are eagerly anticipated over the coming years. Future work in this area should focus on (1) robust biological validation; (2) building biobanks alongside large radiotherapy randomised controlled trials with dose variance (to demonstrate an interaction between radiosensitivity signature and dose); (3) a validation of clinical-grade cost-effective assays that are deliverable within current healthcare infrastructure; and (4) an integration with biomarkers of other determinants of radiation response.

Minimally invasive treatment of early, good prognosis breast cancer-is this feasible?

Breast cancer screening programmes frequently detect early, good prognosis breast cancers with significant treatment burden for patients, and associated health-cost implications. Emerging evidence suggests a role for minimally invasive techniques in the management of these patients enabling many women to avoid surgical intervention. Minimally invasive techniques include vacuum-assisted excision, cryoablation, and radiofrequency ablation. We review published evidence in relation to the risks and benefits of each technique and discuss ongoing trials. Data to date are promising, and we predict a trend towards minimally invasive treatment for early, good-prognosis breast cancer as technical skills, suitability criteria, and follow-up protocols are established.

Axillary Surgery for Breast Cancer in 2024

Axillary surgery for patients with breast cancer (BC) in 2024 is becoming increasingly specific, moving away from the previous 'one size fits all' radical approach. The goal is to spare morbidity whilst maintaining oncologic safety. In the upfront surgery setting, a first landmark randomized controlled trial (RCT) on the omission of any surgical axillary staging in patients with unremarkable clinical examination and axillary ultrasound showed non-inferiority to sentinel lymph node (SLN) biopsy (SLNB). The study population consisted of 87.8% postmenopausal patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative BC. Patients with clinically node-negative breast cancer and up to two positive SLNs can safely be spared axillary dissection (ALND) even in the context of mastectomy or extranodal extension. In patients enrolled in the TAXIS trial, adjuvant systemic treatment was shown to be similar with or without ALND despite the loss of staging information. After neoadjuvant chemotherapy (NACT), targeted lymph node removal with or without SLNB showed a lower false-negative rate to determine nodal pathological complete response (pCR) compared to SLNB alone. However, oncologic outcomes do not appear to differ in patients with nodal pCR determined by either one of the two concepts, according to a recently published global, retrospective, real-world study. Real-world studies generally have a lower level of evidence than RCTs, but they are feasible quickly and with a large sample size. Another global real-world study provides evidence that even patients with residual isolated tumor cells can be safely spared from ALND. In general, few indications for ALND remain. Three randomized controlled trials are ongoing for patients with clinically node-positive BC in the upfront surgery setting and residual disease after NACT. Pending the results of these trials, ALND remains indicated in these patients.

Omission of radiation therapy after breast conserving surgery for older women at low-risk of local recurrence: One option among many

This editorial discusses the evolving landscape of early-stage breast cancer treatment, emphasizing the need to tailor therapies based on disease biology and genomic approaches. The focus is on the reconsideration of postoperative radiation therapy (RT) for older patients with low-risk, hormone receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) breast cancer. Recent trials show modest long-term local recurrence rates with the omission of RT after BCS in certain cases, challenging the traditional approach. The commentary calls for continued research on predictive tests for treatment response and advocates for a multidisciplinary approach to decision-making, considering factors like quality of life. The nuanced risk/benefit ratio of RT in older patients is explored, emphasizing the importance of comprehensive assessment for optimal therapy.

Omission of radiation therapy post breast conserving surgery

Radiation therapy (RT) after breast conserving surgery decreases the risks of local recurrence and breast cancer mortality in the multidisciplinary management of patients with breast cancer. However, breast cancer is a heterogeneous disease, and the absolute benefit of post-operative RT in individual patients varies substantially. Clinical trials aiming to identify patients with low-risk early breast cancer in whom post-operative RT may be safely omitted, based on conventional clinical-pathologic variables alone, have not provided sufficiently tailored information on local recurrence risk assessment to guide treatment decisions. The majority of patients with early breast cancer continue to be routinely treated with RT after breast conserving surgery. This approach may represent over-treatment for a substantial proportion of the patients. The clinical impact of genomic signatures on local therapy decisions for early breast cancer has been remarkably modest due to the lack of high-level evidence supporting their clinical validity for assessment of the risk of local recurrence. Efforts to personalise breast cancer care must be supported by high level evidence to enable balanced, informed treatment decisions. These considerations underpin the importance of ongoing biomarker-directed clinical trials to generate the high-level evidence necessary for setting the future standard of care in personalised local therapy for patients with early breast cancer.

LUMINA: Using molecular biomarkers to guide decision making for breast radiotherapy

In this opinion piece, we respond to comments about the LUMINA trial by Meattini and colleagues in the Journal. LUMINA was a prospective cohort study which evaluated the omission of radiotherapy after breast conserving surgery (BCS) in patients treated with endocrine therapy with low risk clinico-pathologic features and luminal A breast cancer. We address their areas of concern including the single cohort design that required careful patient selection, the relatively short follow-up period of 5 years, and the limited follow-up on younger patients. The Ki67 biomarker was key to defining the luminal A phenotype. We clarify the evidence supporting the Ki67 criteria used. The compliance with endocrine therapy was high and similar to other contemporary trials. Based on the results of LUMINA, and mounting evidence from other trials, we feel comfortable offering our patients the option of no radiotherapy after BCS if they fit the trial eligibility criteria from LUMINA and have decided to receive adjuvant endocrine therapy. We concur that a patient-centered approach to treatment decision making should be used to make patients aware of all available information including the results of the LUMINA trial when deciding on post-operative breast radiotherapy.