Retrospective Analysis of Pyrotinib-Based Therapy for Metastatic Breast Cancer: Promising Efficacy in Combination with Trastuzumab.

Purpose: To evaluate the efficacy and safety of a pyrotinib-based therapy for human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) in the real world. Methods: Clinical data of 218 patients with HER2-positive MBC who received a pyrotinib-based therapy from January 2020 to March 2023 at the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. Results: Finally, 195 patients were included in the efficacy cohort. The median progression-free survival (PFS) in the total population is 12.4 months (95% CI, 9.8-15.0 months). More than half of the patients in the efficacy cohort received pyrotinib mono-targeted therapy (103 cases, 52.8%). Among the remaining patients, 74 (37.9%) patients chose a combined trastuzumab-targeted therapy and 17 (8.7%) chose to combine inetetamab. Median PFS in the pyrotinib group vs pyrotinib plus trastuzumab group was 10.5 months vs 20.1 months (P<0.001). The median PFS of primary trastuzumab resistance population reached to 20.1 months in pyrotinib plus trastuzumab group. Double-targets' advantage was also observed in the brain metastases subgroup (17.9 months vs 10.0 months, P=0.386). The patients who received pyrotinib plus inetetamab as second and higher-line treatment reached a median PFS of 7.9 months (95% CI, 4.0-11.8 months). Forty-one (19.8%) of 207 patients included in the safety cohort experienced grade 3 or higher diarrhea, the most common adverse event in safety analysis, and no adverse event-related deaths. Conclusion: The combination of pyrotinib and trastuzumab demonstrated promising efficacy in the treatment of HER2-positive metastatic breast cancer, including those who had primary resistance to trastuzumab and brain metastases. Pyrotinib plus trastuzumab is expected to be a potent option in the first-line. Additionally, the concurrent administration of pyrotinib and inetetamab could be an alternative to consider in the second and higher-line treatment for metastatic breast cancer. The adverse reactions of pyrotinib were tolerable in general.

Neoadjuvant pyrotinib plus trastuzumab and chemotherapy for HER2-positive breast cancer: a prospective cohort study.

BACKGROUND: This prospective study aims to investigate the efficacy and safety of pyrotinib (P) combined with 4 cycles of epirubicin and cyclophosphamide followed by 4 cycles of taxane and trastuzumab (P + EC-TH) regimen as neoadjuvant therapy for human epidermal growth factor receptor 2 (HER2) positive breast cancer and to investigate the predictive value of p53, p63, and epidermal growth factor receptor (EGFR) status for neoadjuvant efficacy. METHODS: A total of 138 HER2-positive breast cancer patients who received neoadjuvant therapy and underwent surgery were included. Case group: 55 patients received P + EC-TH regimen. CONTROL GROUP: 83 patients received EC-TH regimen. The chi-square test, Fisher's exact test, and logistic regression analysis were applied. The primary endpoint was total pathologic complete response (tpCR), and the secondary endpoints were breast pathologic complete response (bpCR), overall response rate (ORR), and adverse events (AEs). RESULTS: In the case group, the tpCR rate was 63.64% (35/55), the bpCR rate was 69.09% (38/55), and the ORR was 100.00% (55/55). In the control group, the tpCR rate was 39.76% (33/83), the bpCR rate was 44.58% (37/83), and the ORR was 95.18% (79/83). The case group had significantly higher tpCR and bpCR rates than those of the control group (P < 0.05), but there was no significant difference in ORR (P > 0.05). The tpCR was associated with the status of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR), and the patients with any negative ER, PR, AR, or combined, were more likely to achieve tpCR than those with positive results (P < 0.05). The p53-positive patients were more likely to achieve tpCR and bpCR than p53-negative patients (P < 0.05). The incidence of hypokalemia and diarrhea in the case group was higher than that in the control group (P < 0.05). The AEs developed were all manageable, and no treatment-related death occurred. CONCLUSION: The efficacy and safety of the P + EC-TH regimen were verified by this study. The HER2-positive breast cancer patients treated with the EC-TH neoadjuvant regimen were more likely to achieve tpCR or bpCR if pyrotinib was administered simultaneously.

Effects of groundwater depth on ecological stoichiometric characteristics of assimilated branches and soil of two desert plants.

Groundwater plays a crucial role in regulating plant growth in arid regions and has significant effects on plant physiological mechanisms. However, research on the influence of groundwater change on plant ecological stoichiometry is still limited. Therefore, this study was carried out to obtain the variations in assimilated branches and soil ecological stoichiometry of two dominant species in the Gurbantunggut Desert (Haloxylon ammodendron and Haloxylon persicum) at different groundwater depths to reveal the responses of desert plants to groundwater depth changes. The results showed that (1) H. persicum branches' stress tolerance indicators (C:N, C:P) are higher, while nutritional indicators (N:P) are lower. The soil nutrient of H. ammodendron is richer. (2) The ecological stoichiometry varied significantly along the groundwater gradient. With the deepening of groundwater, the branches C, N and P increased, and the variation in element ratio was inconsistent. Most of the soil properties was inversely proportional to the depth of groundwater. (3) Groundwater depth was a vital environmental factor affecting the assimilated branches ecological stoichiometry. Soil properties also had a significant influence on element accumulation in assimilated branches. (4) Regulating the allocation of branches ecological stoichiometry is an adaptation of two Haloxylon species to cope with local hydrological conditions changes. These findings provide novel insights into desert plant responses to different groundwater conditions within fragile desert ecosystems and may have implications for the implementation of effective measures related to the stability and sustainability of desert ecosystems.

Circ_0001387 regulates SKA2 to accelerate breast cancer progression through miR-136-5p.

BACKGROUND: Growing evidence has revealed the critical regulatory role for circular RNAs (circRNAs) in cancer. This study aimed to explore the function of circ_0001387 in breast cancer (BC). METHODS: Circ_0001387, miR-136-5p, and spindle and kinetochore-associated protein 2 (SKA2) levels were analyzed by quantitative real-time polymerase chain reaction. Clone formation and 5-ethynyl-2'-deoxyuridine assays were used to analyze cell proliferation. Cell apoptosis and cell migration and invasion abilities were analyzed using flow cytometry or transwell assay. Mechanism assay was used to confirm the association between miR-136-5p and circ_0001387 or SKA2. The effect of circ_0001387 on tumor growth in vivo was analyzed by the xenograft mice model. RESULTS: Circ_0001387 and SKA2 were expressed at high levels, whereas miR-136-5p was lowly expressed in BC tissues and cells. Meanwhile, the downregulation of circ_0001387 restrained BC cell progression in vitro and in vivo. Circ_0001387 competitively bound to miR-136-5p to regulate BC cell malignant behaviors. SKA2 was targeted by miR-136-5p, and SKA2 reinstated the suppressive effect of miR-136-5p upregulation in BC cells. CONCLUSION: Our study indicated that circ_0001387 contributed to BC cell progression through miR-136-5p/SKA2 axis.

Niche stiffness sustains cancer stemness via TAZ and NANOG phase separation.

Emerging evidence shows that the biomechanical environment is required to support cancer stem cells (CSCs), which play a crucial role in drug resistance. However, how mechanotransduction signals regulate CSCs and its clinical significance has remained unclear. Using clinical-practice ultrasound elastography for patients' lesions and atomic force microscopy for surgical samples, we reveal that increased matrix stiffness is associated with poor responses to neoadjuvant chemotherapy, worse prognosis, and CSC enrichment in patients with breast cancer. Mechanically, TAZ activated by biomechanics enhances CSC properties via phase separation with NANOG. TAZ-NANOG phase separation, which is dependent on acidic residues in the N-terminal activation domain of NANOG, promotes the transcription of SOX2 and OCT4. Therapeutically, targeting NANOG or TAZ reduces CSCs and enhances the chemosensitivity in vivo. Collectively, this study demonstrated that the phase separation of a pluripotency transcription factor links mechanical cues in the niche to the fate of CSCs.

CD16+ fibroblasts foster a trastuzumab-refractory microenvironment that is reversed by VAV2 inhibition.

The leukocyte Fcγ receptor (FcγR)-mediated response is important for the efficacy of therapeutic antibodies; however, little is known about the role of FcγRs in other cell types. Here we identify a subset of fibroblasts in human breast cancer that express CD16 (FcγRIII). An abundance of these cells in HER2+ breast cancer patients is associated with poor prognosis and response to trastuzumab. Functionally, upon trastuzumab stimulation, CD16+ fibroblasts reduce drug delivery by enhancing extracellular matrix stiffness. Interaction between trastuzumab and CD16 activates the intracellular SYK-VAV2-RhoA-ROCK-MLC2-MRTF-A pathway, leading to elevated contractile force and matrix production. Targeting of a Rho family guanine nucleotide exchange factor, VAV2, which is indispensable for the function of CD16 in fibroblasts rather than leukocytes, reverses desmoplasia provoked by CD16+ fibroblasts. Collectively, our study reveals a role for the fibroblast FcγR in drug resistance, and suggests that VAV2 is an attractive target to augment the effects of antibody treatments.

Retraction: Long non-coding RNA PVT1 facilitates cell proliferation by epigenetically regulating FOXF1 in breast cancer.

[This retracts the article DOI: 10.1039/C7RA12042G.].

Identification of novel prognostic risk signature of breast cancer based on ferroptosis-related genes.

Ferroptosis is a type of cell regulated necrosis triggered by intracellular phospholipid peroxidation, which is more immunogenic than apoptosis. Therefore, genes controlling ferroptosis may be promising candidate biomarkers for tumor therapy. In this study, we investigate the function of genes associated with ferroptosis in breast cancer (BC) and systematically evaluate the relationship between ferroptosis-related gene expression and prognosis of BC patients from the Cancer Genome Atlas database. By using the consensus clustering method, 1203 breast cancer samples were clustered into two clearly divided subgroups based on the expression of 237 ferroptosis-related genes. Then differentially expressed analysis and least absolute shrinkage and selection operator were used to identify the prognosis-related genes. Furthermore, the genetic risk signature was constructed using the expression of prognosis-related genes. Our results showed that the genetic risk signature can identify patient subgroups with distinct prognosis in either training cohort or validation, and the genetic risk signature was associated with the tumor immune microenvironment. Finally, the Cox regression analysis indicated that our risk signature was an independent prognostic factor for BC patients and this signature was verified by the polymerase chain reaction and western blot. Within this study, we identified a novel prognostic classifier based on five ferroptosis-related genes which may provide a new reference for the treatment of BRCA patients.

Retrospective analysis: 5509 cases of "totally implantable venous access port systems implantation (TIVAPS) depth" assisted by digital radiography.

PURPOSE: Modern oncological treatment in breast cancer patients requires the precise delivery of chemotherapy infusion into the central venous systems without toxicity. TIVAPS is the significant method of chemotherapy delivery although certain internal or external complications associated with their placement. However, the long-term use of TIVAPS is still a concern to minimize the complications such as venous thrombosis syndrome (VTS) and cardiac defects. The aim of this study is to investigate the potential disadvantages that may be avoided by digital radiography (DR)-assisted measurement of catheter depth pertinent to TIVAPS implanted system. METHODS: Retrospective analysis related to 5509 TIVAPS recipients of 99% female breast cancer patients and 1% male blood disorder patients registered from April 2013 to November 2017 were included in the study. Patients with TIVAPS catheter tip depth into superior vena cava into upper (group A), middle (group B), and lower (group C) parts were stratified for evaluation during implantation; DR-assisted measurement of TIVAPS was performed to decipher "tip depth of catheter" and determined the relevance of tip depth to complications such as VTS and cardiac defects. RESULTS: Incidence of VTS complications were significantly higher in TIVAPS recipients of group A (82.7%) than group B (16%) and group C (0.12%) in which the "tip depth of TIVAPS was deeper" (P < 0.01). Defects in heart function are higher in group C (59.6%) than group A (15.8%) and group B (24.6%) in which the "tip depth of TIVAPS was deeper" (P < 0.01). CONCLUSION: DR-assisted measurement can more accurately determine the depth of TIVAPS catheter implantation, and avoid the incidence of related complications, and provide a better method for surgeons.

Development and Validation of a Prognostic Classifier Based on Lipid Metabolism-Related Genes for Breast Cancer.

Background: The changes of lipid metabolism have been implicated in the development of many tumors, but its role in breast invasive carcinoma (BRCA) remains to be fully established. Here, we attempted to ascertain the prognostic value of lipid metabolism-related genes in BRCA. Methods: We obtained RNA expression data and clinical information for BRCA and normal samples from public databases and downloaded a lipid metabolism-related gene set. Ingenuity Pathway Analysis (IPA) was applied to identify the potential pathways and functions of Differentially Expressed Genes (DEGs) related to lipid metabolism. Subsequently, univariate and multivariate Cox regression analyses were utilized to construct the prognostic gene signature. Functional enrichment analysis of prognostic genes was achieved by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Kaplan-Meier analysis, Receiver Operating Characteristic (ROC) curves, clinical follow-up results were employed to assess the prognostic potency. Potential compounds targeting prognostic genes were screened by Connectivity Map (CMap) database and a prognostic gene-drug interaction network was constructed using Comparative Toxicogenomics Database (CTD). Furthermore, we separately validated the selected marker genes in BRCA samples and human breast cancer cell lines (MCF-7, MDA-MB-231). Results: IPA and functional enrichment analysis demonstrated that the 162 lipid metabolism-related DEGs we obtained were involved in many lipid metabolism and BRCA pathological signatures. The prognostic classifier we constructed comprising SDC1 and SORBS1 can serve as an independent prognostic marker for BRCA. CMap filtered 37 potential compounds against prognostic genes, of which 16 compounds could target both two prognostic genes were identified by CTD. The functions of the two prognostic genes in breast cancer cells were verified by cell function experiments. Conclusion: Within this study, we identified a novel prognostic classifier based on two lipid metabolism-related genes: SDC1 and SORBS1. This result highlighted a new perspective on the metabolic exploration of BRCA.

Patient Management Strategies in Perioperative, Intraoperative, and Postoperative Period in Breast Reconstruction With DIEP-Flap: Clinical Recommendations.

BACKGROUND AND OBJECTIVE: Deep Inferior Epigastric Perforator (DIEP) flap is a tissue isolated from the skin and subcutaneous tissue of the lower abdomen or rectus muscle to foster breast reconstruction. There is limited information about DIEP-flap induced complications associated with breast reconstruction surgery. EVIDENCE: We conducted a systematic review of the published literature in the field of breast cancer reconstruction surgery. Information was gathered through internet resources such as PubMed, Medline, eMedicine, NLM, and ReleMed etc. The following key phrases were used for effective literature collection: "DIEP flap", "Breast reconstruction", "Patient management", "Postoperative DIEP", "Intraoperative anticoagulant therapy", "Clinical recommendations". A total of 106 research papers were retrieved pertaining to this systematic review. CONCLUSION: A successful breast reconstruction with DIEP-flap without complications is the priority achievement for this surgical procedure. This study provides various evidence-based recommendations on patient management in the perioperative, intraoperative, and postoperative periods. The clinical recommendations provided in this review can benefit surgeons to execute breast reconstruction surgery with minimal postoperative complications. These recommendations are beneficial to improve clinical outcomes when performing surgery by minimizing complications in perioperative, intraoperative, and postoperative period.

Breast Cancer Stem Cells-derived Extracellular Vesicles Affect PPARG Expression by Delivering MicroRNA-197 in Breast Cancer Cells.

BACKGROUND: Breast cancer (BC) is the most frequently diagnosed cancer in women, and over 90% of BC-related deaths are associated with metastasis. The effects of BC stem cells-derived extracellular vesicles (BCSCs-EVs) have been implicated in cancer control. This work aims to probe to the relevance of BCSCs-EVs to liver metastases of BC cells and the molecules involved. METHODS: First, EVs were extracted from BCSCs for MDA-MB-231 and SUM149PT cell co-culture. The effects of BCSCs-EVs on the proliferation of BC cells in vitro and in vivo as well as liver metastasis were evaluated. Subsequently, we analyzed differentially expressed microRNAs (miRNAs) after BCSCs-EVs by microRNA microarray and had them verified by RT-qPCR. Bioinformatics analysis was conducted to analyze target mRNAs of miR-197. The binding relationship of miR-197 to PPARG mRNA was examined. Finally, MDA-MB-231 and SUM149PT cells co-cultured with BCSCs-EVs were treated with miR-197 inhibitor or a PPARG-specific agonist. RESULTS: BCSCs-EVs promoted the growth of MDA-MB-231 and SUM149PT cells in vitro and in vivo as well as liver metastasis. BCSCs-EVs increased the expression of miR-197 in MDA-MB-231 and SUM149PT cells, and miR-197 could target PPARG mRNA. BCSCs-EVs treatment inhibited the mRNA and protein expression of PPARG in cells, thereby activating epithelial-mesenchymal transition (EMT). Knockdown of miR-197 or activation of PPARG in BCSCs-EVs-treated cells significantly counteracted the promoting effect of BCSCs-EVs on BC cell growth and metastasis. CONCLUSION: BCSCs-EVs facilitated EMT of BC cells by delivering miR-197 to BC cells and inhibiting PPARG expression, thereby promoting growth and metastasis of BC cells.

Circular RNA circ_IRAK3 contributes to tumor growth through upregulating KIF2A via adsorbing miR-603 in breast cancer.

BACKGROUND: Breast cancer (BC) threatens the health of women around the world. Researchers have proved that hsa_circ_0005505 (circ_IRAK3) facilitates BC cell invasion and migration, but the regulatory mechanisms of circ_IRAK3 in BC remain mostly unknown. We aim to explore a new mechanism by which circ_IRAK3 promotes BC progression. METHODS: Levels of circ_IRAK3, microRNA (miR)-603, and kinesin family member 2A (KIF2A) mRNA in BC tissues and cells were examined by quantitative real-time polymerase chain reaction (qRT-PCR). The cell cycle progression, colony formation, and proliferation of BC cells were evaluated by flow cytometry, plate clone, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assays. The migration, invasion, and apoptosis of BC cells were determined by transwell or flow cytometry assays. Several protein levels were detected using western blotting. The targeting relationship between circ_IRAK3 or KIF2A and miR-603 was verified via dual-luciferase reporter assay. The role of circ_IRAK3 in vivo was verified by xenograft assay. RESULTS: We observed higher levels of circ_IRAK3 in BC tissues and cell lines than their respective controls. Functional experiments presented that circ_IRAK3 silencing induced BC cell apoptosis, curbed cell proliferation, migration, and invasion in vitro, and decreased tumor growth in vivo. Mechanistically, circ_IRAK3 could modulate kinesin family member 2A (KIF2A) expression through acting as a microRNA (miR)-603 sponge. miR-603 silencing impaired the effects of circ_IRAK3 inhibition on the malignant behaviors of BC cells. Also, the repressive effects of miR-603 mimic on the malignant behaviors of BC cells were weakened by KIF2A overexpression. CONCLUSIONS: circ_IRAK3 exerted a promoting effect on BC progression by modulating the miR-603/KIF2A axis, providing a piece of novel evidence for circ_IRAK3 as a therapeutic target for BC.

Mitochondrial mutations and mitoepigenetics: Focus on regulation of oxidative stress-induced responses in breast cancers.

Epigenetic regulation of mitochondrial DNA (mtDNA) is an emerging and fast-developing field of research. Compared to regulation of nucler DNA, mechanisms of mtDNA epigenetic regulation (mitoepigenetics) remain less investigated. However, mitochondrial signaling directs various vital intracellular processes including aerobic respiration, apoptosis, cell proliferation and survival, nucleic acid synthesis, and oxidative stress. The later process and associated mismanagement of reactive oxygen species (ROS) cascade were associated with cancer progression. It has been demonstrated that cancer cells contain ROS/oxidative stress-mediated defects in mtDNA repair system and mitochondrial nucleoid protection. Furthermore, mtDNA is vulnerable to damage caused by somatic mutations, resulting in the dysfunction of the mitochondrial respiratory chain and energy production, which fosters further generation of ROS and promotes oncogenicity. Mitochondrial proteins are encoded by the collective mitochondrial genome that comprises both nuclear and mitochondrial genomes coupled by crosstalk. Recent reports determined the defects in the collective mitochondrial genome that are conducive to breast cancer initiation and progression. Mutational damage to mtDNA, as well as its overproliferation and deletions, were reported to alter the nuclear epigenetic landscape. Unbalanced mitoepigenetics and adverse regulation of oxidative phosphorylation (OXPHOS) can efficiently facilitate cancer cell survival. Accordingly, several mitochondria-targeting therapeutic agents (biguanides, OXPHOS inhibitors, vitamin-E analogues, and antibiotic bedaquiline) were suggested for future clinical trials in breast cancer patients. However, crosstalk mechanisms between altered mitoepigenetics and cancer-associated mtDNA mutations remain largely unclear. Hence, mtDNA mutations and epigenetic modifications could be considered as potential molecular markers for early diagnosis and targeted therapy of breast cancer. This review discusses the role of mitoepigenetic regulation in cancer cells and potential employment of mtDNA modifications as novel anti-cancer targets.

Coexpression Module Construction by Weighted Gene Coexpression Network Analysis and Identify Potential Prognostic Markers of Breast Cancer.

Background: Breast cancer (BC) is a malignant tumor with the highest morbidity among women, disrupting millions of their lives worldwide each year. However, the molecular mechanisms underlying remain unclear. Materials and Methods: The RNA-Sequencing and clinical data of BC patients from The Cancer Genome Atlas (TCGA) database were analyzed by weighted gene coexpression network analysis (WGCNA). Additionally, coexpressed modules were used to detect their correlation with the clinical traits of BC. Next, nodes of the most significant coexpression modules were used for Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, mRNA-lncRNA coexpression network and survival analyses. Results: In total, 2056 differentially expressed mRNAs (DEmRNAs) and 297 differentially expressed lncRNAs (DElncRNAs) were identified and subjected to WGCNA analysis, and 12 coexpression modules were generated. The top five significant modules (turquoise, green, red, brown, and blue modules) were related to one or more clinical traits of BC. In particular, the turquoise and green modules were chosen for further analysis. Next, by lncRNA-mRNA coexpression analysis of the turquoise and green modules, 12 DEmRNAs and 2 DElncRNAs were identified as hub nodes. The lncRNA-associated mRNAs of the networks were commonly related to several cancer-related pathways. Moreover, these networks also revealed central roles for RP11-389C8.2 and TGFBR2 in the turquoise module and MYLK, KIT, and RP11-394O4.5 in the green module. Furthermore, 16 DEmRNAs and 3 DElncRNAs in these two modules were significantly correlated with the overall survival of BC patients. Conclusions: The authors' study identified some prognostic biomarkers that might play important roles in the development and treatment of BC. In particular, lncRNAs AC016995.3, RP1-193H18.2, and RP11-166D19.1 were novel biomarkers for BC.

Transcription Factor FOSL1 Enhances Drug Resistance of Breast Cancer through DUSP7-Mediated Dephosphorylation of PEA15.

Breast cancer is one of the commonest malignancies in women with first occurrence and fifth mortality in the world. However, drug resistance has always been a major obstacle to cancer treatment. Transcription factors have been reported to have close association with drug resistance of tumors. Recently, by analyzing the data from Gene Expression Omnibus database (GSE76540), we found that transcription factor FOS like 1, AP-1 transcription factor subunit (FOSL1) was significantly upregulated in the transcriptome of doxorubicin-resistant breast cancer cells compared with that in sensitive parental cells. Therefore, we aim to explore the regulatory mechanism of FOSL1 in affecting the drug resistance of breast cancer cells. FOSL1 expression in doxorubicin-resistant breast cancer cells was firstly examined through qRT-PCR, and then its influence on the drug resistance of breast cancer cells was explored through a series of in vitro and in vivo mechanism assays. Results showed that FOSL1 promoted the drug resistance of breast cancer cells to doxorubicin both in intro and in vivo. It positively regulated the transcription of dual specificity phosphatase 7 (DUSP7) in breast cancer doxorubicin-resistant cells and DUSP7 also enhanced the drug resistance of breast cancer cells. Furthermore, FOSL1 promoted the dephosphorylation of proliferation and apoptosis adaptor protein 15 (PEA15) through DUSP7. In conclusion, it was verified that FOSL1 promoted the drug resistance in breast cancer through DUSP7-mediated dephosphorylation of PEA15. IMPLICATIONS: These initial findings suggest that the FOSL1/DUSP7/PEA15 pathway may provide a theoretical guidance for breast cancer treatment.