A Novel Biosignature Identifies Patients With DCIS With High Risk of Local Recurrence After Breast Conserving Surgery and Radiation Therapy

Current pattern of care in radiation therapy for DCIS in Australia and New Zealand - where are we heading?

BACKGROUND

Ductal carcinoma in-situ (DCIS) is a non-obligate precursor breast lesion with variable tendency to become invasive malignancy. Multiple studies have attempted to identify patient groups that could avoid radiation therapy (RT). We investigated the recent surgical management of DCIS in Australia and New Zealand (ANZ) and evaluated the likely rates of RT delivery dependent on differing low risk predictive criteria compared to actual practice.

METHOD

The BreastSurgANZ Quality Audit identified patients with DCIS from 2018 to 2022. Data were analysed on multiple DCIS characteristics as well as postoperative RT recommendations. Existing potential RT avoidance characteristics, low risk classification criteria (LRCC) and RTOG 9804, were tested against the cohort.

RESULTS

7790 cases were analysed with 5323 (68.33 %) undergoing breast conservation surgery (BCS). There was higher median age, lower tumour grade and smaller size in the BCS group compared to mastectomy (p < 0.001). According to the BQA, 25.38 % of patients had RT omitted. Using LRCC, 1659 patients (31.17 %) could omit RT but only 760 (45.81 %) of those patients did. When using RTOG 9804 criterion, 1287 patients (24.18 %) could omit RT but only 447 (34.73 %) did. Of 3477 patients with neither low risk classifying characteristics, 553 (15.9 %) had no RT.

CONCLUSION

BCS is the preferred surgical management of DCIS in ANZ. Currently RT is omitted following BCS in 25 % of cases. Using LRCC and RTOG 9804 low risk classifiers there was inconsistent avoidance of RT, whereas RT was avoided in 15.9 % of higher risk patients. More consistent and transparent selection methods are desirable and currently genomic testing and clinico-molecular tools appears promising.

Impact of a 7-Gene Predictive Biosignature on Adjuvant Radiation Therapy Recommendations in Patients Undergoing Breast-Conserving Surgery for Ductal Carcinoma In Situ

BACKGROUND

Breast conservation therapy for patients with ductal carcinoma in situ (DCIS) includes breast-conserving surgery (BCS) with postoperative radiotherapy (RT). Because RT does not impact overall survival, identifying women who do not benefit from RT would allow de-escalation of therapy. We evaluated the impact of a novel 7-gene DCIS biosignature on adjuvant radiation recommendations for patients undergoing BCS for DCIS.

STUDY DESIGN

Seven-gene biosignature was evaluated in women diagnosed with DCIS between 2019 and 2022. Seven-gene biosignature is reported as a "decision score" (DS) and categorical risk groups. RT recommendation before and after 7-gene biosignature was identified through retrospective chart review after IRB approval. The impact of the DS on RT recommendations was assessed using McNemar's test. The 7-gene biosignature DS was compared between treatment types by t -test.

RESULTS

A total of 101 patients underwent BCS for DCIS. Of those, 24 (24%) met Radiation Therapy Oncology Group 9804 criteria and 45 (45%) had nuclear grade 3 DCIS. Before 7-gene biosignature testing, all 101 patients were recommended RT; after testing, 35 patients omitted RT, corresponding to a 35% decision change (p < 0.0001). Patients who ultimately omitted radiation had a significantly lower decision score (DS median 0.9) vs those who received RT (DS median 3.7; p < 0.0001). There were 22 of 39 patients (56%) with DS lower than 2 and 11 of 40 patients (28%) with DS 2 to 4 who were not treated with RT. More patients with DS higher than 4 (20 of 22, 91%) were treated with RT than DS lower than 2 (p < 0.001), and patients with DS higher than 4 were treated with an increased RT dose (p = 0.028).

CONCLUSIONS

The 7-gene biosignature test resulted in a 35% reduction in patients treated with adjuvant RT. Patients with higher DSs were more likely to receive RT and to receive a greater RT dose.

Reimagining Deintensification for Low-Risk Breast Cancer

As outcomes for low-risk breast cancer continue to improve, research and clinical paradigms are increasingly focused on appropriate deintensification with the goal of improving the therapeutic ratio of breast cancer treatment. These deintensification approaches span across disciplines including breast surgery, radiation therapy, and systemic therapy. With regard to breast surgery, studies have continued to push deintensification when it comes to surgical margins with breast conservation, reducing re-excision rates, whereas deintensification of axillary surgery has reduced the rates of axillary lymph node dissection and increasingly the need for any axillary surgery, including sentinel lymph node biopsy for low-risk patients. With regard to radiation therapy, studies have allowed for a drastic reduction in treatment duration, whereas approaches that reduce the target of treatment have led to a change from from treatment daily for 5-7 weeks to many low-risk patients completing treatment in just five treatments. With regard to systemic therapy, use of genomic assays and tumor biology has led to reduced utilization of cytotoxic chemotherapy, with studies also allowing for dose reduction of endocrine therapy for patients with ductal carcinoma in situ. Moving forward, greater focus should be placed on interdisciplinary deintensification approaches such as the consideration of radiation therapy alone as compared with endocrine therapy alone for low-risk breast cancers.

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.

Three-Dimensional Models: Biomimetic Tools That Recapitulate Breast Tissue Architecture and Microenvironment to Study Ductal Carcinoma In Situ Transition to Invasive Ductal Breast Cancer

Diagnosis of ductal carcinoma in situ (DCIS) presents a challenge as we cannot yet distinguish between those lesions that remain dormant from cases that may progress to invasive ductal breast cancer (IDC) and require therapeutic intervention. Our overall interest is to develop biomimetic three-dimensional (3D) models that more accurately recapitulate the structure and characteristics of pre-invasive breast cancer in order to study the underlying mechanisms driving malignant progression. These models allow us to mimic the microenvironment to investigate many aspects of mammary cell biology, including the role of the extracellular matrix (ECM), the interaction between carcinoma-associated fibroblasts (CAFs) and epithelial cells, and the dynamics of cytoskeletal reorganization. In this review article, we outline the significance of 3D culture models as reliable pre-clinical tools that mimic the in vivo tumor microenvironment and facilitate the study of DCIS lesions as they progress to invasive breast cancer. We also discuss the role of CAFs and other stromal cells in DCIS transition as well as the clinical significance of emerging technologies like tumor-on-chip and co-culture models.

A 7-Gene Biosignature for Ductal Carcinoma in situ of the Breast Identifies Subpopulations of HER2-positive Patients With Distinct Recurrence Rates After Breast-Conserving Surgery and Radiation Therapy

PURPOSE

A subpopulation of women with ductal carcinoma in situ (DCIS) remains at risk for in-breast recurrence (IBR) following breast-conserving surgery (BCS) and radiation therapy (RT). The NSABP B-43 trial evaluated the role of concurrent RT and trastuzumab in patients with HER2-positive DCIS but did not reach the prespecified endpoint. We hypothesized that a 7-gene biosignature (DCISionRT) with its Residual Risk subtype (RRt) could identify 2 groups of HER2(3+) patients with significantly different IBR risks after BCS plus RT.

PATIENTS AND METHODS

All patients with HER2(3+) DCIS (n = 178) treated with BCS plus RT were selected from a combined multinational patient cohort. Treatment decisions were neither randomized nor strictly rules-based. Biosignature testing was performed on all patients and stratified with previously defined groups: (1) Combined Low Risk group (DS ≤ 2.8) and Elevated Risk group (DS > 2.8) without RRt or (2) Residual Risk subtype. Kaplan-Meier analysis was used to compute IBR curves.

RESULTS

Sixty-three percent of HER2(3+) patients (113/178) were classified into the Residual Risk subtype. These patients had significantly higher 10-year rates of IBR compared to the nonresidual risk group (16.2% vs. 1.6%, P = .01). The Residual Risk subtype had more nuclear grade 3 disease (87% vs. 63%, P < .001), but age, size, and grade were not associated with IBR rate (P = NS) on univariate and multivariable analysis. Only the Residual Risk group was associated with IBR (P = .05) in multivariate analysis.

CONCLUSION

The 7-gene biosignature with RRt identified a subset of HER2(3+) patients with greater IBR rates following BCS and RT beyond traditional clinical and pathologic features. Consideration of therapies to reduce these elevated IBR rates should be evaluated, including the incorporation of HER2-targeted therapy.

Evaluation of tumor infiltrating lymphocytes as a prognostic biomarker in patients with ductal carcinoma in situ of the breast

PURPOSE

To assess the association between tumor-infiltrating lymphocytes (TILs) in ductal carcinoma in situ (DCIS) samples and disease recurrence.

METHODS

This retrospective cohort study included women aged 18 years and older who underwent treatment between January 2007 and December 2020. Male patients, individuals diagnosed with invasive or microinvasive disease based on anatomopathological examination of surgical specimens, and those with a personal history of any other cancers were excluded. Additionally, the presence of "touching TILs" (lymphocytes in direct contact with tumor cells) and periductal desmoplasia were evaluated as complementary methods to represent the immunological microenvironment. The primary outcome was relapse-free survival based on TIL quantification adjusted for potential confounders. Pathologists assessed TILs in the sample with the highest tumor representation and quantified them as a percentage. Survival was evaluated using Kaplan‒Meier curves, log-rank tests, and Cox regression models.

RESULTS

A total of 191 patients met the eligibility criteria. The mean follow-up duration was 77.2 months, with a recurrence rate of 9.2%. Patients with TILs ≥ 17% had a greater risk of recurrence (HR 2.97, 95% CI 1.17-7.51; p = 0.02). Additionally, focal necrosis (HR 6.4, 95% CI 1.39-34.71; p = 0.018) or comedonecrosis (HR 4.53, 95% CI 1.34-15.28; p = 0.015) were associated with increased recurrence risk. According to the multivariate model, comedonecrosis and TILs ≥ 17% were significantly associated with recurrence (p = 0.034 and p = 0.035, respectively). Regarding the evaluations of "touching TILs" and periductal desmoplasia, no statistical significance was found when assessing their association with disease recurrence.

CONCLUSION

In our cohort, a high percentage of TILs (≥ 17%) and the presence of comedonecrosis were independently associated with DCIS recurrence.

Outcomes from low-risk ductal carcinoma in situ: a systematic review and meta-analysis

PURPOSE

The current standard of treatment for ductal carcinoma in situ (DCIS) is surgery with or without adjuvant radiotherapy. With a growing debate about overdiagnosis and overtreatment of low-risk DCIS, active surveillance is being explored in several ongoing trials. We conducted a systematic review and meta-analysis to evaluate the recurrence of low-risk DCIS under various treatment approaches.

METHODS

PubMed, Embase, Web of Science, and Cochrane were searched for studies reporting ipsilateral breast tumour event (IBTE), contralateral breast cancer (CBC), and breast cancer-specific survival (BCSS) rates at 5 and 10 years in low-risk DCIS. The primary outcome was invasive IBTE (iIBTE) defined as invasive progression in the ipsilateral breast.

RESULTS

Thirty three eligible studies were identified, involving 47,696 women with low-risk DCIS. The pooled 5-year and 10-year iIBTE rates were 3.3% (95% confidence interval [CI]: 1.3, 8.1) and 5.9% (95% CI: 3.8, 9.0), respectively. The iIBTE rates were significantly lower in patients who underwent surgery compared to those who did not, at 5 years (3.5% vs. 9.0%, P = 0.003) and 10 years (6.4% vs. 22.7%, P = 0.008). Similarly, the 10-year BCSS rate was higher in the surgery group (96.0% vs. 99.6%, P = 0.010). In patients treated with breast-conserving surgery, additional radiotherapy significantly reduced IBTE risk, but not total-CBC risk.

CONCLUSION

This review showed a lower risk of progression and better survival in women who received surgery and additional RT for low-risk DCIS. However, our findings were primarily based on observational studies, and should be confirmed with the results from the ongoing trials.

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.

Molecular Expression Assays Improve the Prediction of Local and Invasive Local Recurrence After Breast-Conserving Surgery for Ductal Carcinoma In Situ

PURPOSE

Ductal carcinoma in situ (DCIS) is routinely treated with adjuvant radiotherapy (RT) after breast-conserving surgery (BCS). The inability to accurately estimate an individual's risk of local recurrence (LR) and invasive LR using clinicopathologic factors (CPF) contributes to the overtreatment of DCIS. We examined the impact of the 12-gene DCIS Score (DS) and the 21-gene Recurrence Score (RS) on the accuracy of predicting LR and invasive LR.

METHODS

A population-based cohort diagnosed with pure DCIS treated with BCS ± RT from 1994 to 2003 was used. All patients had expert pathology review and assessment of the DS and RS. Predictive models (CPF alone, DS + CPF, and RS + CPF) were developed using multivariable Cox regression analyses to predict 10-year LR and invasive LR risks. Models were evaluated on the basis of c-statistic, -2log likelihood estimate (-2LLE), and Akaike information criterion. Calibration was performed using bootstrap resamples, with replacement.

RESULTS

The cohort includes 1,226 women treated with BCS; 712 received RT. 194 women (15.8%) experienced ipsilateral LR as a first event; 112 were invasive. Models including the DS or RS performed better in predicting the 10-year risk of LR compared with models on the basis of CPF alone with excellent calibration. The two molecular-based models also performed better in predicting invasive LR compared with the CPF model but the model incorporating the RS did not perform better in the prediction of invasive LR compared with the DS-based model.

CONCLUSION

Models incorporating the DS or RS more accurately predicted the 10-year risk of LR and invasive LR after BCS compared with models on the basis of CPF alone. Inclusion of the RS, compared with DS, did not improve the prediction of the 10-year risk of invasive LR.

The Clinical Utility of a 7-Gene Biosignature on Radiation Therapy Decision Making in Patients with Ductal Carcinoma In Situ Following Breast-Conserving Surgery: An Updated Analysis of the DCISionRT® PREDICT Study

BACKGROUND

Breast-conserving surgery (BCS) followed by adjuvant radiotherapy (RT) is a standard treatment for ductal carcinoma in situ (DCIS). A low-risk patient subset that does not benefit from RT has not yet been clearly identified. The DCISionRT test provides a clinically validated decision score (DS), which is prognostic of 10-year in-breast recurrence rates (invasive and non-invasive) and is also predictive of RT benefit. This analysis presents final outcomes from the PREDICT prospective registry trial aiming to determine how often the DCISionRT test changes radiation treatment recommendations.

METHODS

Overall, 2496 patients were enrolled from February 2018 to January 2022 at 63 academic and community practice sites and received DCISionRT as part of their care plan. Treating physicians reported their treatment recommendations pre- and post-test as well as the patient's preference. The primary endpoint was to identify the percentage of patients where testing led to a change in RT recommendation. The impact of the test on RT treatment recommendation was physician specialty, treatment settings, individual clinical/pathological features and RTOG 9804 like criteria. Multivariate logisitc regression analysis was used to estimate the odds ratio (ORs) for factors associated with the post-test RT recommendations.

RESULTS

RT recommendation changed 38% of women, resulting in a 20% decrease in the overall recommendation of RT (p < 0.001). Of those women initially recommended no RT (n = 583), 31% were recommended RT post-test. The recommendation for RT post-test increased with increasing DS, from 29% to 66% to 91% for DS <2, DS 2-4, and DS >4, respectively. On multivariable analysis, DS had the strongest influence on final RT recommendation (odds ratio 22.2, 95% confidence interval 16.3-30.7), which was eightfold greater than clinicopathologic features. Furthermore, there was an overall change in the recommendation to receive RT in 42% of those patients meeting RTOG 9804-like low-risk criteria.

CONCLUSIONS

The test results provided information that changes treatment recommendations both for and against RT use in large population of women with DCIS treated in a variety of clinical settings. Overall, clinicians changed their recommendations to include or omit RT for 38% of women based on the test results. Based on published clinical validations and the results from current study, DCISionRT may aid in preventing the over- and undertreatment of clinicopathological 'low-risk' and 'high-risk' DCIS patients.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03448926 ( https://clinicaltrials.gov/study/NCT03448926 ).

Genetic profiling in radiotherapy: a comprehensive review

This comprehensive review explores the pivotal role of radiotherapy in cancer treatment, emphasizing the diverse applications of genetic profiling. The review highlights genetic markers for predicting radiation toxicity, enabling personalized treatment planning. It delves into the impact of genetic profiling on radiotherapy strategies across various cancer types, discussing research findings related to treatment response, prognosis, and therapeutic resistance. The integration of genetic profiling is shown to transform cancer treatment paradigms, offering insights into personalized radiotherapy regimens and guiding decisions in cases where standard protocols may fall short. Ultimately, the review underscores the potential of genetic profiling to enhance patient outcomes and advance precision medicine in oncology.

Ductal carcinoma in situ of the breast: finding the balance between overtreatment and undertreatment

Ductal carcinoma in situ (DCIS) accounts for 15-25% of all breast cancer diagnoses. Its prognosis is excellent overall, the main risk being the occurrence of local breast events, as most cases of DCIS do not progress to invasive cancer. Systematic screening has greatly increased the incidence of this non-obligate precursor of invasion, lending urgency to the need to identify DCIS that is prone to invasive progression and distinguish it from non-invasion-prone DCIS, as the latter can be overdiagnosed and therefore overtreated. Treatment strategies, including surgery, radiotherapy, and optional endocrine therapy, decrease the risk of local events, but have no effect on survival outcomes. Active surveillance is being evaluated as a possible new option for low-risk DCIS. Considerable efforts to decipher the biology of DCIS have led to a better understanding of the factors that determine its variable natural history. Given this variability, shared decision making regarding optimal, personalised treatment strategies is the most appropriate course of action. Well designed, risk-based de-escalation studies remain a major need in this field.

Tools to Guide Radiation Oncologists in the Management of DCIS

Similar to invasive breast cancer, ductal carcinoma in situ is also going through a phase of changes not only from a technical but also a conceptual standpoint. From prescribing radiotherapy to everyone to personalized approaches, including radiotherapy omission, there is still a lack of a comprehensive framework to guide radiation oncologists in decision making. Many pieces of the puzzle are finding their place as high-quality data mature and are disseminated, but very often, the interpretation of risk factors and the perception of risk remain very highly subjective. Sharing the therapeutic choice with patients requires effective communication for an understanding of risks and benefits, facilitating an informed decision that does not increase anxiety and concerns about prognosis. The purpose of this narrative review is to summarize the current state of knowledge to highlight the tools available to radiation oncologists for managing DCIS, with an outlook on future developments.

Lumpectomy without radiation for ductal carcinoma in situ of the breast: 20-year results from the ECOG-ACRIN E5194 study

We report the 20-year rate of ipsilateral breast event (IBE) for patients with ductal carcinoma in situ (DCIS) treated with lumpectomy without radiation on a non-randomized prospective clinical trial. Patients were enrolled in cohort 1: low- or intermediate-grade DCIS, size ≤ 2.5 cm (n = 561); or cohort 2: high-grade DCIS, size ≤ 1 cm (n = 104). The Kaplan-Meier method was used to estimate time-to-event distributions. Cox proportional hazard methods were used to estimate hazard ratios (HRs) and tests for significance for event times. 561 patients were enrolled in cohort 1 and 104 in cohort 2. After central pathology review, 26% in cohort 1 were recategorized as high-grade and 26% in cohort 2 as low- or intermediate-grade. Mean DCIS size was similar at 7.5 mm in cohort 1 and 7.8 mm in cohort 2. Surgical margin was ≥3 mm in 96% of patients, and about 30% received tamoxifen. Median follow-up was 19.2 years. There were 104 IBEs, of which 54 (52%) were invasive. The IBE and invasive IBE rates increased in both cohorts up to 15 years, then plateaued. The 20-year IBE rates were 17.8% for cohort 1 and 28.7% for cohort 2 (p = 0.005), respectively. Invasive IBE occurred in 9.8% and 15.1% (p = 0.09), respectively. On multivariable analysis, IBE risk increased with size and was higher in cohort 2, but grade and margin width were not significantly associated with IBE. For patients with DCIS treated with excision without radiation, the rate of IBE increased with size and assigned cohort mostly in the first 15 years.

Histology Specific Molecular Biomarkers: Ushering in a New Era of Precision Radiation Oncology

Histopathology and clinical staging have historically formed the backbone for allocation of treatment decisions in oncology. Although this has provided an extremely practical and fruitful approach for decades, it has long been evident that these data alone do not adequately capture the heterogeneity and breadth of disease trajectories experienced by patients. As efficient and affordable DNA and RNA sequencing have become available, the ability to provide precision therapy has become within grasp. This has been realized with systemic oncologic therapy, as targeted therapies have demonstrated immense promise for subsets of patients with oncogene-driver mutations. Further, several studies have evaluated predictive biomarkers for response to systemic therapy within a variety of malignancies. Within radiation oncology, the use of genomics/transcriptomics to guide the use, dose, and fractionation of radiation therapy is rapidly evolving but still in its infancy. The genomic adjusted radiation dose/radiation sensitivity index is one such early and exciting effort to provide genomically guided radiation dosing with a pan-cancer approach. In addition to this broad method, a histology specific approach to precision radiation therapy is also underway. Herein we review select literature surrounding the use of histology specific, molecular biomarkers to allow for precision radiotherapy with the greatest emphasis on commercially available and prospectively validated biomarkers.

Can Molecular Biomarkers Help Reduce the Overtreatment of DCIS?

Ductal carcinoma in situ (DCIS), especially in the era of mammographic screening, is a commonly diagnosed breast tumor. Despite the low breast cancer mortality risk, management with breast conserving surgery (BCS) and radiotherapy (RT) is the prevailing treatment approach in order to reduce the risk of local recurrence (LR), including invasive LR, which carries a subsequent risk of breast cancer mortality. However, reliable and accurate individual risk prediction remains elusive and RT continues to be standardly recommended for most women with DCIS. Three molecular biomarkers have been studied to better estimate LR risk after BCS-Oncotype DX DCIS score, DCISionRT Decision Score and its associated Residual Risk subtypes, and Oncotype 21-gene Recurrence Score. All these molecular biomarkers represent important efforts towards improving predicted risk of LR after BCS. To prove clinical utility, these biomarkers require careful predictive modeling with calibration and external validation, and evidence of benefit to patients; on this front, further research is needed. Most trials do not incorporate molecular biomarkers in evaluating de-escalation of therapy for DCIS; however, one-the Prospective Evaluation of Breast-Conserving Surgery Alone in Low-Risk DCIS (ELISA) trial-incorporates the Oncotype DX DCIS score in defining a low-risk population and is an important next step in this line of research.

Ductal Carcinoma In Situ (DCIS) and Microinvasive DCIS: Role of Surgery in Early Diagnosis of Breast Cancer

Advances in treatments, screening, and awareness have led to continually decreasing breast cancer-related mortality rates in the past decades. This achievement is coupled with early breast cancer diagnosis. Ductal carcinoma in situ (DCIS) and microinvasive breast cancer have increasingly been diagnosed in the context of mammographic screening. Clinical management of DCIS is heterogenous, and the clinical significance of microinvasion in DCIS remains elusive, although microinvasive DCIS (DCIS-Mi) is distinct from "pure" DCIS. Upfront surgery has a fundamental role in the overall treatment of these breast diseases. The growing number of screen-detected DCIS diagnoses with clinicopathological features of low risk for local recurrence (LR) allows more conservative surgical options, followed by personalised adjuvant radiotherapy plans. Furthermore, studies are underway to evaluate the validity of surgery omission in selected low-risk categories. Nevertheless, the management, the priority of axillary surgical staging, and the prognosis of DCIS-Mi remain the subject of debate, demonstrating how the paucity of data still necessitates adequate studies to provide conclusive guidelines. The current scientific scenario for DCIS and DCIS-Mi surgical approach consists of highly controversial and diversified sources, which this narrative review will delineate and clarify.