Breast cancer remains one of the most prevalent malignancies worldwide, and radiation therapy is a central component of its management. However, intrinsic or acquired resistance to radiation significantly compromises therapeutic efficacy. This systematic review aimed to identify and evaluate molecular mechanisms and interventions that influence radiation sensitivity in breast cancer models. A comprehensive PubMed search was conducted using the terms “breast cancer” and “radiation resistance” for studies published between 2002 and 2024. Seventy-nine eligible studies were included. The most frequently investigated mechanisms included the dysregulation of the PI3K/AKT/mTOR and MAPK signaling pathways, enhanced DNA damage repair via non-homologous end joining (NHEJ), and the overexpression of cancer stem cell markers such as CD44⁺/CD24⁻/low and ALDH1. Several studies highlighted the role of non-coding RNAs, particularly the lncRNA DUXAP8 and microRNAs such as miR-21, miR-144, miR-33a, and miR-634, in modulating radiation response. Components of the tumor microenvironment, including cancer-associated fibroblasts and immune regulators, also contributed to radiation resistance. By synthesizing current evidence, this review provides a consolidated resource to guide future mechanistic studies and therapeutic development. This review highlights promising molecular targets and emerging strategies to enhance radiosensitivity and offers a foundation for translational research aimed at improving outcomes in radiation-refractory breast cancer.

Radiation resistance presents a significant challenge in the treatment of triple-negative breast cancer (TNBC). To investigate the molecular adaptations associated with radiation therapy resistance, MDA-MB-231 cells were subjected to a repeated radiation (RR) regimen totaling 57 Gy over 11 weeks, followed by clonal selection. The resulting radiation-adapted cells (MDA-MB-231^RR) were analyzed using whole-transcriptome RNA sequencing, revealing substantial dysregulation of pathways related to cell adhesion, mitochondrial function, and epithelial–mesenchymal transition (EMT). These transcriptional changes were corroborated by functional assays. MDA-MB-231^RR cells exhibited reduced expression of adhesion receptors (ITGB1, ITGA2, ITGA6) and extracellular matrix proteins (fibronectin, collagen, laminins), accompanied by significantly impaired cell adhesion to fibronectin, collagen, and laminin substrates. Mitochondrial dysfunction was supported by downregulation of oxidative phosphorylation genes (MTCO1, MTND1) and confirmed by JC-1 dye assays demonstrating a marked reduction in mitochondrial membrane potential. EMT-associated changes included increased mesenchymal markers and loss of epithelial markers (CTNNB1, SNAI2, CK19), consistent with enhanced migratory potential. Taken together, this study delineates key molecular features of radiation adaptation in TNBC, providing a foundation for the development of targeted therapies to overcome treatment resistance.

Minimal residual disease (MRD) is a major contributor to colorectal cancer (CRC) recurrence following curative-intent treatment, yet conventional surveillance methods may fail to detect residual disease at its earliest stages. Circulating tumor DNA (ctDNA) has emerged as a minimally invasive biomarker for MRD detection and postoperative monitoring. We conducted a structured PubMed-based literature review and included 94 publications evaluating ctDNA in CRC. Across the literature, postoperative ctDNA positivity was consistently associated with increased recurrence risk and poorer disease-free and overall survival, while serial monitoring improved detection sensitivity and enabled assessment of treatment response. ctDNA frequently identified molecular recurrence approximately 2.5–11.5 months before conventional surveillance. Both tumor-informed and tumor-naive strategies were represented, using PCR/ddPCR, targeted next-generation sequencing, whole-exome or whole-genome sequencing, methylation-based assays, and emerging multiomic approaches. Although ctDNA demonstrates strong prognostic value, evidence supporting treatment modification based solely on ctDNA status remains limited. Further prospective randomized trials, assay standardization, and consensus clinical guidelines are required before routine implementation. Overall, ctDNA is a promising tool for recurrence prediction, surveillance, and precision management of CRC.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype lacking estrogen receptor, progesterone receptor, and HER2 expression. Although ionizing radiation (IR) is widely used to treat TNBC, tumour radioresistance remains a major therapeutic barrier. Tumour hypoxia contributes to resistance by limiting IR-induced reactive oxygen species generation and activating pathways that promote tumour survival, progression, and aggressiveness. Hypoxia-inducible factors (HIFs) are oxygen-sensitive transcription factors that regulate many of these pathways; however, the mechanisms underlying HIF-mediated radioresistance in TNBC remain incompletely characterized. This review examines the role of HIF signalling in TNBC radiation resistance and emerging strategies for overcoming hypoxia-mediated radioresistance. PubMed and Web of Science were searched for studies investigating HIFs, TNBC, and radiation response. Relevant studies were screened against the eligibility criteria and analyzed for mechanistic findings and therapeutic interventions targeting HIF-associated pathways. The literature indicates that HIF activation promotes radioresistance through multiple mechanisms, including altered ferroptosis and pH regulation. Proposed countermeasures include pharmacologic inhibition of HIF signalling, nanotechnology-based delivery systems, and alternative radiation-based modalities, including photodynamic and radiodynamic therapies. Collectively, these findings identify HIF signalling as a central mediator of TNBC radioresistance and a promising therapeutic target for improving radiotherapy outcomes.