Examination of a paradox: recurrent metastatic breast cancer incidence decline without improved distant disease survival: 1990-2011

Associations amongst genes, molecules, cells, and organs in breast cancer metastasis

This paper is a cross fertilization of ideas about the importance of molecular aspects of breast cancer metastasis by basic scientists, a pathologist, and clinical oncologists at the Henry Ford Health symposium. We address four major topics: (i) the complex roles of lymphatic endothelial cells and the molecules that stimulate them to enhance lymph node and systemic metastasis and influence the anti-tumor immunity that might inhibit metastasis; (ii) the interaction of molecules and cells when breast cancer spreads to bone, and how bone metastases may themselves spread to internal viscera; (iii) how molecular expression and morphologic subtypes of breast cancer assist clinicians in determining which patients to treat with more or less aggressive therapies; (iv) how the outcomes of patients with oligometastases in breast cancer are different from those with multiple metastases and how that could justify the aggressive treatment of these patients with the hope of cure.

The Evolving Role of Genomic Testing in Early Breast Cancer: Implications for Diagnosis, Prognosis, and Therapy

Multigene prognostic genomic assays have become indispensable in managing early breast cancer (EBC), offering crucial information for risk stratification and guiding adjuvant treatment strategies in conjunction with traditional clinicopathological parameters. The American Society of Clinical Oncology (ASCO) guidelines endorse these assays, though some clinical contexts still lack definitive recommendations. The dynamic landscape of EBC management demands further refinement and optimization of genomic assays to streamline their incorporation into clinical practice. The breast cancer community is poised at the brink of transformative advances in enhancing the clinical utility of genomic assays, aiming to significantly improve the precision and effectiveness of both diagnosis and treatment for women with EBC. This article methodically examines the testing methodologies, clinical validity and utility, costs, diagnostic frameworks, and methodologies of the established genomic tests, including the Oncotype Dx Breast Recurrence Score®, MammaPrint, Prosigna®, EndoPredict®, and Breast Cancer Index (BCI). Among these tests, Prosigna and EndoPredict® have at present been validated only on a prognostic level, while Oncotype Dx, MammaPrint, and BCI hold both a prognostic and predictive role. Oncologists and pathologists engaged in the management of EBC will find in this review a thorough comparison of available genomic assays, as well as strategies to optimize the utilization of the information derived from them.

Long-term Survival Among Patients With De Novo Human Epidermal Growth Receptor 2-Positive Metastatic Breast Cancer in Manitoba

OBJECTIVES

Although metastatic breast cancer (MBC) is considered incurable, human epidermal growth receptor 2 (HER2)-directed therapy has improved outcomes significantly, with some patients experiencing durable responses to treatment. The aim of this study was to identify potential predictors of long-term survival (LTS) among patients with de novo HER2-positive MBC who received HER2-directed treatment.

METHODS

Eligible patients from 2008 to 2018 were identified using the Manitoba Cancer Registry. LTS was defined as survival ≥5 years from the time of diagnosis. Univariate logistic regression models were performed to assess variables of clinical interest and the odds of LTS. Overall survival (OS) was defined as the time from diagnosis of MBC to death of any cause. OS was estimated using the Kaplan-Meier method with log-rank comparative analyses as a univariate analysis. A Cox proportional hazards model was used for OS estimates in a univariate analysis.

RESULTS

A total of 62 patients were diagnosed with de novo HER2-positive MBC and received HER2-directed therapy. Eighteen (29%) achieved LTS. The median OS of the whole cohort was 50.2 months (95% CI: 28.6-not reached). Radiographic response to first-line treatment was associated with LTS; complete and partial responses were both associated with higher odds of LTS (odds ratio: 28.33 [95% CI: 2.47-4006.71, P = 0.0043] and odds ratio: 7.80 [95% CI: 0.7317-1072.00, P = 0.0972], respectively). The best radiographic response was associated with improved OS.

CONCLUSIONS

Radiographic response to first-line HER2-directed therapy is a predictor for LTS in patients with de novo HER2-positive MBC. Larger studies are needed to identify patients who can safely discontinue HER2-targeted therapy.

Management of patients with advanced-stage HER2-positive breast cancer: current evidence and future perspectives

Amplification and/or overexpression of ERBB2, the gene encoding HER2, can be found in 15-20% of invasive breast cancers and is associated with an aggressive phenotype and poor clinical outcomes. Relentless research efforts in molecular biology and drug development have led to the implementation of several HER2-targeted therapies, including monoclonal antibodies, tyrosine-kinase inhibitors and antibody-drug conjugates, constituting one of the best examples of bench-to-bedside translation in oncology. Each individual drug class has improved patient outcomes and, importantly, the combinatorial and sequential use of different HER2-targeted therapies has increased cure rates in the early stage disease setting and substantially prolonged survival for patients with advanced-stage disease. In this Review, we describe key steps in the development of the modern paradigm for the treatment of HER2-positive advanced-stage breast cancer, including selecting and sequencing new-generation HER2-targeted therapies, and summarize efficacy and safety outcomes from pivotal studies. We then outline the factors that are currently known to be related to resistance to HER2-targeted therapies, such as HER2 intratumoural heterogeneity, activation of alternative signalling pathways and immune escape mechanisms, as well as potential strategies that might be used in the future to overcome this resistance and further improve patient outcomes.

Efficacy of metformin and electrical pulses in breast cancer MDA-MB-231 cells

Aim

Triple-negative breast cancer (TNBC) is a very aggressive subset of breast cancer, with limited treatment options, due to the lack of three commonly targeted receptors, which merits the need for novel treatments for TNBC. Towards this need, the use of metformin (Met), the most widely used type-2 diabetes drug worldwide, was explored as a repurposed anticancer agent. Cancer being a metabolic disease, the modulation of two crucial metabolites, glucose, and reactive oxygen species (ROS), is studied in MDA-MB-231 TNBC cells, using Met in the presence of electrical pulses (EP) to enhance the drug efficacy.

Methods

MDA-MB-231, human TNBC cells were treated with Met in the presence of EP, with various concentrations Met of 1 mmol/L, 2.5 mmol/L, 5 mmol/L, and 10 mmol/L. EP of 500 V/cm, 800 V/cm, and 1,000 V/cm (with a pulse width of 100 µs at 1 s intervals) were applied to TNBC and the impact of these two treatments was studied. Various assays, including cell viability, microscopic inspection, glucose, ROS, and wound healing assay, were performed to characterize the response of the cells to the combination treatment.

Results

Combining 1,000 V/cm with 5 mmol/L Met yielded cell viability as low as 42.6% at 24 h. The glucose level was reduced by 5.60-fold and the ROS levels were increased by 9.56-fold compared to the control, leading to apoptotic cell death.

Conclusions

The results indicate the enhanced anticancer effect of Met in the presence of electric pulses. The cell growth is inhibited by suppressing glucose levels and elevated ROS. This shows a synergistic interplay between electroporation, Met, glucose, and ROS metabolic alterations. The results show promises for combinational therapy in TNBC patients.

Decline in the Incidence of Distant Recurrence of Breast Cancer: A Population-Based Health Record Linkage Study, Australia 2001-2016

BACKGROUND

We investigated differences in cumulative incidence of first distant recurrence (DR) following non-metastatic breast cancer over a time period when new adjuvant therapies became available in Australia.

METHODS

We conducted a health record linkage study of females with localized (T1-3N0) or regional (T4 or N+) breast cancer in the New South Wales Cancer Registry in 2001 to 2002 and 2006 to 2007. We linked cancer registry records with administrative records from hospitals, dispensed medicines, radiotherapy services, and death registrations to estimate the 9-year cumulative incidence of DR and describe use of adjuvant treatment.

RESULTS

The study included 13,170 women (2001-2002 n = 6,338, 2006-2007 n = 6,832). The 9-year cumulative incidence of DR was 3.6% [95% confidence interval (CI), 2.3%-4.9%] lower for 2006-2007 diagnoses (15.0%) than 2001-2002 (18.6%). Differences in the annual hazard of DR between cohorts were largest in year two. DR incidence declined for localized and regional disease. Decline was largest for ages <40 years (absolute difference, 14.4%; 95% CI, 8.3%-20.6%), whereas their use of adjuvant chemotherapy (2001-2002 49%, 2006-2007 75%) and HER2-targeted therapy (2001-2002 0%, 2006-2007 16%) increased. DR did not decline for ages ≥70 years (absolute difference, 0.9%; 95% CI, -3.6%-1.8%) who had low use of adjuvant chemotherapy and HER2-targeted therapy.

CONCLUSIONS

This whole-of-population study suggests that DR incidence declined over time. Decline was largest for younger ages, coinciding with changes to adjuvant breast cancer therapy.

IMPACT

Study findings support the need for trials addressing questions relevant to older people and cancer registry surveillance of DR to inform cancer control programs.

De Novo Oligometastatic Breast Cancer

De novo oligometastatic breast cancer, a unique disease needing new treatment paradigms.

Small breast epithelial mucin as a useful prognostic marker for breast cancer patients

This study aimed to evaluate the clinical utility of small breast epithelial mucin (SBEM) as a prognostic biomarker in an independent patient cohort. The paraffin-embedded tissues and clinicopathological data of 105 patients with breast cancer were collected, and the expression of SBEM in breast cancer samples was detected by immunohistochemical staining. The correlations between clinicopathological variables and the expression of SBEM were analyzed, and its significance as a prognostic indicator for breast cancer patients was determined. Immunohistochemical staining revealed that SBEM was expressed mostly in the cytomembrane and cytoplasm, with markedly increased SBEM expression (≥4 points on staining intensity) observed in 34 of 105 breast cancer tissues (32.4%). Elevated expression of SBEM was found to be significantly associated with larger tumor size (P = 0.002), more frequent lymph node metastasis (P = 0.029), advanced tumor node metastasis stage (P = 0.005), reduced expression of the progesterone receptor (PR) (P = 0.002), and a higher Ki-67 index (P = 0.006). Survival analysis indicated that patients with elevated SBEM expression had worse overall survival (OS) (5-year OS rate: 50.5 vs 93.9% for high and low SBEM expression, respectively, P < 0.001) and disease-free survival (DFS) (5-year DFS rate: 52.8 vs 81.7% for high and low SBEM expression, respectively, P = 0.001) rates than those with low expression of SBEM. Univariate and multivariate Cox analyses demonstrated that elevated expression of SBEM (hazard ratio [HR] = 1.994, 95% confidence interval [CI]: 1.008-3.945, P = 0.047), tumor size (HR = 2.318, 95% CI: 1.071-5.017, P = 0.033), and PR status (HR = 0.195, 95% CI: 0.055-0.694, P = 0.012) were independent predictors of OS in breast cancer patients. Elevated expression of SBEM was associated with both aggressive tumor characteristics and poor survival, indicating its potential as a useful prognostic biomarker for breast cancer patients.

Incorporating clinicopathological and molecular risk prediction tools to improve outcomes in early HR+/HER2- breast cancer

Stratification of recurrence risk is a cornerstone of early breast cancer diagnosis that informs a patient's optimal treatment pathway. Several tools exist that combine clinicopathological and molecular information, including multigene assays, which can estimate risk of recurrence and quantify the potential benefit of different adjuvant treatment modalities. While the tools endorsed by treatment guidelines are supported by level I and II evidence and provide similar prognostic accuracy at the population level, they can yield discordant risk prediction at the individual patient level. This review examines the evidence for these tools in clinical practice and offers a perspective of potential future risk stratification strategies. Experience from clinical trials with cyclin D kinase 4/6 (CDK4/6) inhibitors in the setting of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) early breast cancer is provided as an illustrative example of risk stratification.

Implications for surveillance for breast cancer patients based on the internally and externally validated BRENDA-metastatic recurrence score

PURPOSE

Although the incidence of distant relapse is decreasing, 20-30% of patients with early breast cancer die of metastasis. The aim of this study is to characterize patients with metastasis-free survival(MFS) less than 5 years, to analyze the most probable site of metastases according to the internally and externally validated BRENDA-score. The BRENDA-score is a combination of the biological subtype and clinical staging.

METHOD

3832 patients with primary diagnosis of breast cancer and either distant metastatic recurrence within 5 years or MFS ≥ 5 years were assigned to this study. Patients were classified for metastatic recurrence according to the BRENDA-score. 1765 patients were in a validation set. Statistical methods were Kaplan-Meier curves, Cox regression analysis, Exhausted CHAID, likelihood-ratio tests and the Nearest Neighbor Estimation method.

RESULTS

There was a significant(p < 0.001) difference between the Kaplan-Meier MFS-functions of M0-patients stratified by BRENDA-score. The BRENDA score outperforms intrinsic subtypes and the Nottingham prognostic score. It fits the original data and the validation set equally well (p = 0.179).There was a significant(p < 0.001) difference between mean BRENDA-Index for patients with MFS < 5y(21.0 ± 9.0) and patients with MFS ≥ 5y(mean BRENDA-Index 11.7 ± 8.2). 55.6% of the very high risk patients(BRENDA-Index ≥ 27) had metastases within 5 years. The most likely primary metastatic site was bone(30%) followed by liver(19%) and lung(18%). The discriminatory ability(areas under the time dependent ROC curve) of the BRENDA score is good to acceptable for the first 5 years. In the very low/low risk (intermediate, high/very high) risk group 50% of all metastases were diagnosed within 26 months. Guideline adherence had a highly significant influence on outcome independent of the risk group.

CONCLUSION

The evaluation showed that the BRENDA-Score is a robust predictive tool for breast cancer recurrence and site of metastases in the first five years after diagnosis. It outperforms intrinsic subtypes and the Nottingham prognostic score. The BRENDA-score could be a tool for a risk orientated and targeted follow up.

Pharmacological Basis of Breast Cancer Resistance to Therapies - An Overview

Breast cancer (BC) is a molecular heterogeneous disease and often patients with similar clinico-pathological characteristics may display different response to treatment. Cellular processes, including uncontrolled cell-cycle, constitutive activation of signalling pathways parallel to or downstream of HER2 and alterations in DNA-repair mechanisms are the main features altered in the tumor. These cellular processes play significant roles in the emergence of therapy resistance. The introduction of target therapies as well as immunotherapies has improved the management of breast cancer. Furthermore, several therapeutic options are available to overcome resistance and physicians could overcome the challenge of resistant BC using combinatorial drug strategies and incorporating novel biomarkers. Molecular profiling promises to help in refine personalized treatment decisions and catalyse the development of further strategies when resistances inevitably occur. The search for biological explanations for treatment failure helps to clarify the phenomenon and allows to incorporate new biomarkers into clinical practice that can lead to adequate solutions to overcome it. This review provides a summary of genetic and molecular aspects of resistance mechanisms to available treatments for BC patients, and its clinical implications.

BRENDA-Score, a Highly Significant, Internally and Externally Validated Prognostic Marker for Metastatic Recurrence: Analysis of 10,449 Primary Breast Cancer Patients

Simple Summary

The BRENDA-Score provides an easy to use tool for clinicians to estimate the risk of recurrence in primary breast cancer. The algorithm has been validated via a second independent database and provides five recurrence risk groups. This grouping helps clinicians to encourage high risk patients to undergo the recommended treatment.

Abstract

Background Current research in breast cancer focuses on individualization of local and systemic therapies with adequate escalation or de-escalation strategies. As a result, about two-thirds of breast cancer patients can be cured, but up to one-third eventually develop metastatic disease, which is considered incurable with currently available treatment options. This underscores the importance to develop a metastatic recurrence score to escalate or de-escalate treatment strategies. Patients and methods Data from 10,499 patients were available from 17 clinical cancer registries (BRENDA-project. In total, 8566 were used to develop the BRENDA-Index. This index was calculated from the regression coefficients of a Cox regression model for metastasis-free survival (MFS). Based on this index, patients were categorized into very high, high, intermediate, low, and very low risk groups forming the BRENDA-Score. Bootstrapping was used for internal validation and an independent dataset of 1883 patients for external validation. The predictive accuracy was checked by Harrell’s c-index. In addition, the BRENDA-Score was analyzed as a marker for overall survival (OS) and compared to the Nottingham prognostic score (NPS). Results: Intrinsic subtypes, tumour size, grading, and nodal status were identified as statistically significant prognostic factors in the multivariate analysis. The five prognostic groups of the BRENDA-Score showed highly significant (p < 0.001) differences regarding MFS:low risk: hazard ratio (HR) = 2.4, 95%CI (1.7–3.3); intermediate risk: HR = 5.0, 95%CI.(3.6–6.9); high risk: HR = 10.3, 95%CI (7.4–14.3) and very high risk: HR = 18.1, 95%CI (13.2–24.9). The external validation showed congruent results. A multivariate Cox regression model for OS with BRENDA-Score and NPS as covariates showed that of these two scores only the BRENDA-Score is significant (BRENDA-Score p < 0.001; NPS p = 0.447). Therefore, the BRENDA-Score is also a good prognostic marker for OS. Conclusion: The BRENDA-Score is an internally and externally validated robust predictive tool for metastatic recurrence in breast cancer patients. It is based on routine parameters easily accessible in daily clinical care. In addition, the BRENDA-Score is a good prognostic marker for overall survival. Highlights: The BRENDA-Score is a highly significant predictive tool for metastatic recurrence of breast cancer patients. The BRENDA-Score is stable for at least the first five years after primary diagnosis, i.e., the sensitivities and specificities of this predicting system is rather similar to the NPI with AUCs between 0.76 and 0.81 the BRENDA-Score is a good prognostic marker for overall survival.

Economic burden of central nervous system metastases in human epidermal growth factor receptor 2-positive breast cancer

Aim: Compare healthcare resource utilization and costs among patients with HER2+ metastatic breast cancer (MBC) with and without central nervous system (CNS) metastases. Methods: Retrospective matched cohort study using IQVIA's PharMetrics^® Plus claims database. Results: Patients with CNS metastases (n = 753) experienced more outpatient, emergency room and inpatient visits versus controls (n = 753; all p < 0.05). In the post-index year, median total all-cause healthcare costs were significantly higher among patients with CNS metastases versus controls ($112,402 vs $50,835; p < 0.0001); outpatient costs primarily drove the cost differential. Conclusion: More effective therapies are needed that improve clinical outcomes and reduce economic burden associated with CNS metastases in patients with HER2+ MBC.

Breast cancer distant recurrence lead time interval by detection method in an institutional cohort

BACKGROUND

Lead time, the interval between screen detection and when a disease would have become clinically evident, has been cited to explain longer survival times in mammography detected breast cancer cases (BC).

METHODS

An institutional retrospective cohort study of BC outcomes related to detection method (mammography (MamD) vs. patient (PtD)). Cases were first primary invasive stage I-III BC, age 40-74 years (n = 6603), 1999-2016. Survival time was divided into 1) distant disease-free interval (DDFI) and 2) distant disease-specific survival (DDSS) as two separate time interval outcomes. We measured statistical association between detection method and diagnostic, treatment and outcome variables using bivariate comparisons, Cox proportional hazards analyses and mean comparisons. Outcomes were distant recurrence (n = 422), DDFI and DDSS.

RESULTS

39% of cases were PtD (n = 2566) and 61% were MamD (n = 4037). MamD cases had a higher percentage of Stage I tumors [MamD 69% stage I vs. PtD 31%, p < .001]. Rate of distant recurrence was 11% among PtD BC cases (n = 289) vs. 3% of MamD (n = 133) (p < .001). Order of factor entry into the distant recurrence time interval (DDFI) model was 1) TNM stage (p < .001), 2) HR/HER2 status (p < .001), 3) histologic grade (p = .005) and 4) detection method (p < .001). Unadjusted PtD DDFI mean time was 4.34 years and MamD 5.52 years (p < .001), however when stratified by stage, the most significant factor relative to distant recurrence, there was no significant difference between PtD and MamD BC. Distant disease specific survival time did not differ by detection method.

CONCLUSION

We observed breast cancer distant disease-free interval to be primarily associated with stage at diagnosis and tumor characteristics with less contribution of detection method to the full model. Patient and mammography detected breast cancer mean lead time to distant recurrence differed significantly by detection method for all stages but not significantly within stage with no difference in time from distant recurrence to death. Lead time difference related to detection method appears to be present but may be less influential than other factors in distant disease-free and disease specific survival.

Prediction of breast cancer distant recurrence using natural language processing and knowledge-guided convolutional neural network

Distant recurrence of breast cancer results in high lifetime risks and low 5-year survival rates. Early prediction of distant recurrent breast cancer could facilitate intervention and improve patients' life quality. In this study, we designed an EHR-based predictive model to estimate the distant recurrent probability of breast cancer patients. We studied the pathology reports and progress notes of 6,447 patients who were diagnosed with breast cancer at Northwestern Memorial Hospital between 2001 and 2015. Clinical notes were mapped to Concept unified identifiers (CUI) using natural language processing tools. Bag-of-words and pre-trained embedding were employed to vectorize words and CUI sequences. These features integrated with clinical features from structured data were downstreamed to conventional machine learning classifiers and Knowledge-guided Convolutional Neural Network (K-CNN). The best configuration of our model yielded an AUC of 0.888 and an F1-score of 0.5. Our work provides an automated method to predict breast cancer distant recurrence using natural language processing and deep learning approaches. We expect that through advanced feature engineering, better predictive performance could be achieved.

Expression of TRPC1 and SBEM protein in breast cancer tissue and its relationship with clinicopathological features and prognosis of patients

This study investigated the relationship of the expression of transient receptor potential channel 1 (TRPC1), small breast epithelial mucin (SBEM) in breast cancer tissues with clinical pathological features and prognosis of patients. Altogether 50 patients with breast cancer who were treated in Weifang People's hospital from April 2017 to November 2018 were selected, and the mRNA and protein differences of TRPC1 and SBEM in breast cancer patients and normal breast cancer tissues were detected by qRT-PCR and Western blot. Spearman test was used for correlation analysis. Logistic univariate and multivariate analysis were performed on the risk factors related to breast cancer metastasis in breast cancer patients. The expression of TRPC1 and SBEM in breast cancer tissues was significantly higher than that in normal breast tissues (P<0.001). The mRNA expression of TRPC1, SBEM and protein was not related to age, tumor size and tissue grade of breast cancer patients, but related to TNM stage, clinical stage and lymph node metastasis (P<0.001). The relative expression of TRPC1 was positively correlated with clinical stage of breast cancer (r=0.992, P<0.001). The relative expression of SBEM was positively correlated with the clinical stage of breast cancer (r=0.853, P<0.001). The relative expression of TRPC1 was positively correlated with TNM staging of breast cancer (r=0.860, P<0.001). The relative expression of SBEM was positively correlated with TNM staging of breast cancer (r=0.880, P<0.001). Multivariate conditional Logistic regression analysis showed that TNM staging, TRPC1, SBEM were independent risk factors for malignant breast cancer metastasis. On the contrary, expression of TRPC1 and SBEM in breast cancer tissues was up-regulated. TRPC1 and SBEM may be involved in the process of breast cancer occurrence, development and metastasis, and can be used as potential tissue biomarkers in diagnosis of breast cancer metastasis and disease assessment.

Optimizing Palbociclib Therapy Across the Age Spectrum: Hypothetical, Illustrative Case Scenarios in HR+, HER2-Metastatic Breast Cancer

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors in combination with endocrine therapy are a preferred treatment option for premenopausal and postmenopausal women with hormone receptor–positive (HR+), human epidermal growth factor receptor 2–negative (HER2–) metastatic breast cancer (mBC). Palbociclib is a potent, first-in-class oral inhibitor of CDK4/6. To provide optimal care to patients with HR+/HER2– mBC receiving palbociclib, advanced practitioners require a thorough understanding of the efficacy and adverse event (AE) profile of palbociclib as well as the diverse characteristics and support needs of patients eligible for palbociclib treatment. This Grand Rounds uses two hypothetical patient scenarios to illustrate core issues in the management of premenopausal and postmenopausal patients receiving palbociclib-based therapy for mBC. In addition to providing an overview of key efficacy and safety data, each case offers practical guidance on providing individualized, patient-centered care, the identification and management of treatment-related AEs, management of concomitant medications, and best practices to promote adherence to therapy.

The Canary in the Coal Mine: Biomaterial Implants to Monitor Cancer Recurrence

Synthetic biomaterials implanted in the body induce a foreign body reaction characterized by chronic inflammation and fibrosis. In this issue of Cancer Research, Oakes and colleagues used biomaterial implants and their associated immunologic activity to develop a "metastasis sensor" for detection of tumor burden at distal sites. A scoring system was developed from computational analysis of gene expression patterns from implant biopsies that could predict the presence of tumor. This unexpected use of biomaterials for early detection of cancer provides a more accurate systemic sampling compared with blood or liquid biopsies and alleviates the need for inefficient imaging and biopsy sampling from potential metastatic target tissues.See related article by Oakes et al., p. 602.

Metastatic breast cancer survival improvement restricted by regional disparity: Surveillance, Epidemiology, and End Results and institutional analysis: 1990 to 2011

Background

The extent of breast cancer outcome disparity can be measured by comparing Surveillance, Epidemiology, and End Results (SEER) breast cancer‐specific survival (BCSS) by region and with institutional cohort (IC) rates.

Methods

Patients who were diagnosed with a first primary, de novo, stage IV breast cancer at ages 25 to 84 years from 1990 to 2011 were studied. The change in 5‐year BCSS over time from 1990 to 2011 was compared using the SEER 9 registries (SEER 9) without the Seattle‐Puget Sound (S‐PS) region (n = 12,121), the S‐PS region alone (n = 1931), and the S‐PS region IC (n = 261). The IC BCSS endpoint was breast cancer death confirmed from chart and/or death certificate and cause‐specific survival for SEER registries. BCSS was estimated using the Kaplan‐Meier method. Hazard ratios (HzR) were calculated using Cox proportional‐hazards models.

Results

For SEER 9 without the S‐PS region, 5‐year BCSS improved 7% (from 19% to 26%) over time, it improved 14% for the S‐PS region (21% to 35%), and it improved 27% for the S‐PS IC (29% to 56%). In the IC Cox proportional‐hazards model, recent diagnosis year, chemotherapy, surgery, and age <70 years were associated with better survival. For SEER 9, additional significant factors were white race and positive hormone receptor status and S‐PS region was associated with better survival (HzR, 0.87; 95% CI, 0.84‐0.90). In an adjusted model, hazard of BC death decreased in the most recent time period (2005‐2011) by 28% in SEER 9 without S‐PS, 43% in the S‐PS region and 45% in the IC (HzR, 0.72 [95% CI, 0.67‐0.76], 0.57 [95% CI, 0.49‐0.66], and 0.55 [95% CI, 0.39‐0.78], respectively).

Conclusions

Over 2 decades, the survival of patients with metastatic breast cancer improved nationally, but with regional survival disparity and differential improvement. To achieve equitable outcomes, access and treatment approaches will need to be identified and adopted.

The observation of a greater improvement in survival with metastatic breast cancer by region indicates progress in treatment and a possible statistical cure, in that patients may be able to live long enough with disease to die of other causes. The direct identification of specific factors related to differential survival rates, such as access to care and molecular subtype‐appropriate treatment, is warranted.