Analysis
For DCIS, RT after BCS reduces recurrence substantially. Some low-risk DCIS patients may be considered for omission of RT under strict criteria (small, low grade, widely excised with clear margins), but accurate imaging and margin assessment are critical to safe selection [13].

Overall synthesis short summary

ü  Adjuvant RT after BCS markedly reduces local recurrence across randomized trials and real-world studies.

ü  Radiological examinations (preoperative MRI, intraoperative imaging, post-NAT MRI) are powerful tools that improve tumor mapping and margin control but must be applied selectively to avoid unnecessary escalation of surgery.

ü  Margin status and timing of RT are modifiable factors strongly associated with local control.

ü  Selective omission of RT can be considered in highly selected low-risk elderly patients, but generally increases recurrence risk.

ü  Clinical decisions must be multidisciplinary, integrating radiology, pathology, surgical technique, systemic therapy and patient preferences.

 Discussion

The results of this systematic review highlight the critical role of adjuvant radiation therapy (RT) in reducing local recurrence after breast-conserving surgery (BCS), while also demonstrating the indispensable contribution of radiological evaluation across preoperative, intraoperative, and postoperative stages. Taken together, the evidence underscores how advance in imaging and careful patient selection can optimize outcomes, refine the balance between oncological safety and breast preservation, and potentially individualize the need for RT in certain subgroups [14].

 Effectiveness of RT in Preventing Local Recurrence: Across randomized trials and meta-analyses, RT consistently emerges as the most effective intervention for lowering recurrence risk following BCS. The seminal NSABP B-06 and Milan trials established equivalence in survival between mastectomy and BCS+RT, but highlighted dramatically higher recurrence in patients treated with BCS alone. More recent pooled analyses by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) confirmed that RT approximately halves the risk of recurrence at 10 years, reducing it from over 30% to below 15% in many subgroups. This effect is robust across tumor sizes, grades, and receptor profiles. Importantly, while systemic therapy has improved local control over the past two decades, RT continues to provide independent benefit [15].

 Radiological Contributions to Local Control: Radiology is central in all phases of breast-conserving treatment. Preoperatively, mammography and ultrasound remain first-line modalities for tumor localization, while magnetic resonance imaging (MRI) has expanded the ability to detect multifocal and metacentric disease, lobular carcinoma, and residual tumor after neoadjuvant therapy (NAT). Although MRI increases mastectomy rates in some cohorts, its judicious use ensures accurate mapping of disease extent and minimizes the risk of positive margins. Intraoperatively, specimen radiography, ultrasound guidance, and emerging optical devices improve the likelihood of complete excision by reducing the incidence of positive or close margins. Given that margin status is one of the strongest predictors of recurrence, these technologies indirectly contribute to lower recurrence even when adjuvant RT is delivered. Postoperatively, radiological surveillance particularly annual mammography remains essential for detecting early recurrences and new primary tumors. Integration of advanced modalities such as digital breast tom synthesis and contrast-enhanced mammography may further refine detection; though long-term outcome data are still limited [16].

 Patient Subgroups and Selective Omission of RT: The possibility of omitting RT in certain subgroups is a recurring theme in the literature. Trials such as CALGB 9343, which examined women ≥70 years with small, ER-positive, node-negative tumors receiving endocrine therapy, demonstrated only a modest increase in recurrence when RT was omitted, without an overall survival disadvantage. These findings suggest that in carefully selected elderly patients with favorable biology and limited life expectancy, omission of RT may be a reasonable option to avoid treatment burden. However, outside this highly selected population, omission of RT generally results in substantial increases in recurrence risk, particularly among younger patients, those with high-grade tumors, HER2-positive or triple-negative cancers, and patients with inadequate margins. Thus, the decision to omit RT should be individualized, incorporating radiological evidence of disease extent, biological markers, comorbidity profiles, and patient preferences [17].

 Tumor Size, Margins, and Multimodality: Tumor size and multimodality remain important determinants of recurrence. Larger tumors (>2–3 cm) and multifocal lesions carry a higher baseline risk even with RT. Radiology, especially preoperative MRI, improves identification of such lesions, allowing for more appropriate surgical planning, whether wider excision or mastectomy. Margin status is another central factor [17-19]. Meta-analyses indicate that even with RT, positive margins significantly increase recurrence risk, while clear margins confer the best outcomes. Intraoperative margin assessment tools including specimen radiography, ultrasound, and Margin Probe reduce re-excision rates and thereby improve oncologic safety [20]. Importantly, radiological evaluation of specimen integrity does not replace pathology but complements it in real time [21].

 Timing of Radiotherapy: Several retrospective cohorts suggest that prolonged delays in starting RT (>12 weeks’ post-surgery) may increase recurrence rates, though the impact is less clear in patients receiving chemotherapy first [22]. Nevertheless, timely initiation of RT is advisable, and radiology can help streamline workflow by ensuring adequate margin clearance before RT planning. Delays often result from reoperations due to positive margins, again emphasizing the value of intraoperative radiological tools [23-25].

 DCIS and Radiological Considerations: In ductal carcinoma in situ (DCIS), RT after BCS significantly reduces both invasive and non-invasive local recurrences. While omission of RT is being explored in low-risk DCIS defined by small size, low grade, and wide negative margins, radiological accuracy is critical to identify these patients [26-28]. Mammography remains the gold standard for DCIS detection, while MRI provides complementary sensitivity for high-grade or extensive lesions. The safety of RT omission in low-risk DCIS remains under investigation, and recurrence rates without RT remain consistently higher in published trials [29].

 Integration with Systemic Therapy: The interplay between systemic therapy and local recurrence should also be acknowledged. Advances in endocrine therapy, chemotherapy, and HER2-targeted therapy have reduced recurrence risk, leading some to question whether RT is equally necessary in all contexts. However, the EBCTCG meta-analysis indicates that the benefits of RT remain significant even in the era of systemic therapy [28-30]. Radiological examination is critical in this integration: accurate assessment of treatment response after NAT by MRI can guide surgical planning and RT field design, reducing unnecessary exposure while maintaining oncologic safety [31].

 Limitations of Current Evidence: Despite strong evidence for the efficacy of RT, several limitations persist. Many trials reporting recurrence outcomes were conducted decades ago, when systemic therapy, surgical techniques, and imaging capabilities were less advanced. This raises questions about the generalizability of older recurrence estimates to modern practice. Furthermore, the heterogeneity in margin definitions, RT techniques (e.g., whole-breast vs. partial-breast irradiation), and radiological protocols complicates direct comparisons [32-34].

Radiological innovations such as digital breast tom synthesis, MRI-guided biopsy, and intraoperative optical imaging have not yet been fully incorporated into randomized trial frameworks with long-term outcomes. Consequently, while these tools show promise in improving margin status and reducing re-excision, their ultimate impact on recurrence and survival requires further study [35].

 Clinical Implications and Future Directions: The convergence of surgery, radiotherapy, and radiology provides an opportunity to refine breast-conserving treatment strategies. Personalized recurrence risk prediction models that incorporate tumor biology, margin status, patient age, and radiological findings may help stratify patients into those who require full-dose RT, those eligible for de-escalated RT (e.g., partial breast irradiation), and those who might safely omit RT altogether. From a radiological standpoint, further standardization of MRI use and intraoperative imaging protocols is needed. Artificial intelligence based image analysis may soon assist in more precise delineation of tumor margins, prediction of response to NAT, and identification of patients at very low recurrence risk [34-36]. Finally, long-term prospective studies are required to validate the safety of RT omission in selected patients. Ongoing trials exploring biomarkers, genomic signatures, and radio genomic correlations may help refine recurrence risk estimation beyond traditional clinical and radiological variables [37-39]. This systematic review affirms that RT remains the cornerstone of recurrence prevention after BCS, reducing recurrence by more than half in most populations. Radiological examination plays a vital complementary role: it guides appropriate patient selection, improves intraoperative margin control, and supports long-term surveillance. While omission of RT may be appropriate in narrowly defined low-risk groups, the overall evidence strongly favors its routine use in breast-conserving treatment. Radiological advances, combined with systemic therapy and personalized risk stratification, offer the potential to further optimize outcomes while minimizing overtreatment [40-42].

Conclusion

Breast-conserving surgery with adjuvant radiotherapy remains the gold standard for early-stage breast cancer due to significantly lower local recurrence rates and equivalent overall survival compared with mastectomy. Omitting RT increases local recurrence, even when radiological assessment is used, though select low-risk patients may tolerate RT omission with careful imaging guidance. Radiological evaluation including preoperative MRI, intraoperative specimen imaging, and post-neoadjuvant therapy assessment enhances tumor delineation, ensures margin clearance, and reduces re-excision, thereby lowering recurrence risk. Personalized treatment planning should integrate tumor biology, patient age, comorbidities, and imaging findings to optimize oncologic and cosmetic outcomes. The combination of BCS, RT, and targeted radiological assessment ensures optimal disease control while preserving breast tissue and quality of life. Future studies should continue to refine imaging protocols, margin assessment techniques, and risk stratification to safely identify patients who might benefit from omission of RT or modified treatment approaches.

 Disclosure Statement

No potential conflict of interest reported by the authors.

 Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

 Authors' Contributions

All authors contributed to data analysis, drafting, and revising of the paper and agreed to be responsible for all the aspects of this work.