Cancer cell extravasation requires iplectin-mediated delivery of MT1-MMP at invadopodia.

BACKGROUND: Invadopodia facilitate cancer cell extravasation, but the molecular mechanism whereby invadopodia-specific proteases such as MT1-MMP are called to invadopodia is unclear. METHODS: Mass spectrometry and immunoprecipitation were used to identify interactors of MT1-MMP in metastatic breast cancer cells. After identification, siRNA and small molecule inhibitors were used to assess the effect these interactors had on cellular invasiveness. The chicken embryo chorioallantoic membrane (CAM) model was used to assess extravasation and invadopodia formation in vivo. RESULTS: In metastatic breast cancer cells, MT1-MMP was found to associate with plectin, a cytolinker and scaffolding protein. Complex formation between plectin and MT1-MMP launches invadopodia formation, a subtype we termed iplectin (i = invadopodial). iPlectin delivers MT1-MMP to invadopodia and is indispensable for regulating cell surface levels of the enzyme. Genetic depletion of plectin with siRNA reduced invadopodia formation and cell invasion in vitro. In vivo extravasation efficiency assays and intravital imaging revealed iplectin to be a key contributor to invadopodia ultrastructure and essential for extravasation. Pharmacologic inhibition of plectin using the small molecule Plecstatin-1 (PST-1) abrogated MT1-MMP delivery to invadopodia and extravasation efficiency. CONCLUSIONS: Anti-metastasis therapeutic approaches that target invadopodia are possible by disrupting interactions between MT1-MMP and iplectin. CLINICAL TRIAL REGISTRATION NUMBER: NCT04608357.

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 Significance of Thyroid Hormone Receptors in Breast Cancer: A Hypothesis-Generating Narrative Review.

BACKGROUND: Breast cancer (BC) is frequently diagnosed among Canadian women. While targeted therapies are available for most BC patients; treatment resistance is common and novel therapeutic targets are of interest. Thyroid hormones (TH) bound to thyroid hormone receptors (THR) influence cell proliferation and differentiation; they are also involved in the growth and development of normal breast tissue. Evidence suggests that THRß is a tumor suppressor in various solid tumors. PURPOSE: This narrative review discusses retrospective studies regarding the clinical relevance of THRß as a potential prognostic biomarker and therapeutic target in BC. METHODS: We consulted with an information specialist to develop a search strategy to find all literature related to THRα expression as a potential prognostic and therapeutic biomarker in breast cancer. The primary search was developed for Medline and translated to Embase. The searches were conducted on the Ovid platform on 18 August 2023. RESULTS: Across seven retrospective studies identified, several have shown an association between higher THRß1 expression with a lower risk of BC recurrence and with longer overall survival. CONCLUSIONS: Some evidence suggests that THRß expression is associated with a lower risk of BC recurrence and death. Validation of THRß as an independent prognostic biomarker and possible predictive biomarker of response to endocrine therapy and/or chemotherapy is of interest. Given that THRß is upstream of the AKT/PI3K pathway, its potential as a predictive biomarker of response to AKT inhibitors and/or PI3K inhibitors may also be of value. Finally, the potential re-purposing of THRß agonists as anti-cancer agents warrants investigation.

The incidence of brain metastases in breast cancer according to molecular subtype and stage: a 10-year single institution analysis.

BACKGROUND: Breast cancer (BC) is the second most common etiology of brain metastases (BrM). We aimed to examine the incidence of BrM among all BC patients presenting to a large tertiary cancer centre over one decade. METHODS: We included all BC patients presenting consecutively between 2009 and 2019 and cross referenced that cohort to a radiotherapy database, identifying patients treated for BrM at any time following their initial presentation. Cumulative incidences (CI) of BrM diagnoses were calculated using death as a competing risk and compared using the Fine-Gray method. Overall survival was estimated using the Kaplan Meier method. RESULTS: We identified 12,995 unique patients. The CI of BrM in patients who initially presented with Stage 0-4 disease was 2.1%, 3.7%, 9.4%, 10.6%, and 28.7%, respectively at 10 years. For 8,951 patients with available molecular subtype data, 6,470 (72%), 961 (11%), 1,023 (11%), and 497 (6%) had hormone-receptor (HR)-positive/ERBB2-, HR-negative/ERBB2-, HR-positive/ERBB2 + , and HR-negative/ERBB2 + disease, respectively; the CI of BrM in each was 7.6%, 25.3%, 24.1%, and 26.6%, at 10 years following BC diagnosis, respectively. Median overall survival (OS) following BC diagnosis and BrM diagnosis was 28 years 95% CI [25, 32] and 10 months 95% CI [9, 12], respectively. CONCLUSIONS: From a large, registry-based study, we observed that patients with ERBB2 + and triple negative BC have the highest incidence of BrM. Our data supports prospective surveillance brain MRI studies. Given advancements in BrM treatment, clinicians should have a low threshold for brain imaging in BC patients with high risk subtypes.

The Canadian Breast Cancer Symposium 2023 Meeting Report.

On 15-16 June 2023, healthcare professionals and breast cancer patients and advocates from across Canada met in Toronto, Ontario, for the 2023 Canadian Breast Cancer Symposium (CBSC.). The CBSC. is a national, multidisciplinary event that occurs every 2 years with the goal of developing a personalized approach to the management of breast cancer in Canada. Experts provided state-of-the-art information to help optimally manage breast cancer patients, including etiology, prevention, diagnosis, experimental biology, and therapy of breast cancer and premalignant breast disease. The symposium also had the objectives of increasing communication and collaboration among breast cancer healthcare providers nationwide and providing a comprehensive and real-life review of the many facets of breast cancer. The sessions covered the patient voice, the top breast cancer papers from different disciplines in 2022, artificial intelligence in breast cancer, systemic therapy updates, the management of central nervous system metastases, multidisciplinary management of ductal carcinoma in situ, special populations, optimization-based individual prognostic factors, toxicity management of novel therapeutics, survivorship, and updates in surgical oncology. The key takeaways of these sessions have been summarized in this conference report.

2020 ASCO, 2023 NCCN, 2023 MASCC/ESMO, and 2019 CCO: a comparison of antiemetic guidelines for the treatment of chemotherapy-induced nausea and vomiting in cancer patients.

Chemotherapy-induced nausea and vomiting (CINV) is a common toxicity that may impair the quality of life of patients with various malignancies ranging from early to end stages. In light of frequent changes to the guidelines for optimal management of CINV, we undertook this narrative review to compare the most recent guidelines published by ASCO (2020), NCCN (2023), MASCC/ESMO (2023), and CCO (2019). The processes undertaken by each organization to evaluate existing literature were also described. Although ASCO, NCCN, MASCC/ESMO, and CCO guidelines for the treatment and prevention of CINV share many fundamental similarities, the literature surrounding low and minimal emetic risk regimens is lacking. Current data regarding adherence to these guidelines is poor and warrants further investigation to improve care.

Brain Metastases in the Setting of Stable Versus Progressing Extracranial Disease Among Patients With Metastatic Breast Cancer.

INTRODUCTION: Women with metastatic breast cancer (BC) are at risk of developing brain metastases (BrM), which may result in significant morbidity and mortality. Given the emergence of systemic therapies with activity in the brain, more breast oncology clinical trials include patients with BrM, but most require extracranial disease progression for trial participation. METHODS: We evaluated the proportion of patients with BC BrM who have intracranial disease progression in the setting of stable extracranial disease in a retrospective cohort study of 751 patients treated between 2008 and 2018 at the Sunnybrook Odette Cancer. Extracranial disease progression was defined as any progression outside of the brain within 4 weeks of a patient's local/regional treatment. Clinical/pathologic characteristics and outcomes were also abstracted from patients' medical records. RESULTS: Of 752 patients in the cohort, 691 were included in our study. Sixty-one patients were excluded due to the presence of a second primary tumor or uncertain tissue origin of the BrM. BC subtype based on the primary tumor was known for 592 (85.6%) patients; 33.1% (n = 196) had HER2+ disease, 40% (n = 237) had HR+/HER2- disease, and 26.9% (n = 159) had triple negative BC. Extracranial disease status was available for 677 patients (98%); 41.1% (n = 284/691) had stable extracranial disease and 56.8% (n = 393/691) had extracranial disease progression within 4 weeks of treatment for BrM. DISCUSSION: A high proportion of patients with BC BrM (41.1%) would be excluded from clinical trials due to stable extracranial disease. Efforts should be made to design trials for this patient population.

Pharmacotherapy for leptomeningeal disease in breast cancer.

Clinical data supporting the best therapeutic approach in leptomeningeal disease (LMD; also known as leptomeningeal metastases or leptomeningeal carcinomatosis) are lacking. Despite the development of new agents and increasing incidence of central nervous system metastases, patients with LMD are often excluded from clinical trials in breast cancer, with very few conducted specifically in LMD. Consequently, current evidence may not provide an accurate reflection of real-world clinical practice. This review aims to provide further insight into the treatment strategies for patients with breast cancer and LMD. We explore differences between clinical and real-world studies, considering inclusion criteria, levels of evidence for LMD diagnosis, and time between diagnosis of LMD and LMD-specific treatment initiation. Patient prognosis is poor; median overall survival is limited to several months, with approximately 10% of patients alive at 12 months. Efficacy results have been reported for various systemic and intrathecal agents in LMD to date. Systemic therapies under investigation for LMD in breast cancer include tucatinib, trastuzumab deruxtecan, and paclitaxel trevatide; trastuzumab is the main intrathecal agent currently under investigation. Recent trials investigating systemic or intrathecal therapies are typically small, single-arm studies, and most are restricted to patients with human epidermal growth factor receptor 2-positive breast cancer. Moreover, the variability among inclusion criteria and response assessment tools makes the interpretation of results difficult. Large retrospective cohorts with various inclusion criteria and treatment regimens provide some real-world data. However, there remains an urgent need for randomised clinical trials which include patients with LMD across all breast cancer subtypes.

Predicting Patterns of Distant Metastasis in Breast Cancer Patients following Local Regional Therapy Using Machine Learning.

Up to 30% of breast cancer (BC) patients will develop distant metastases (DM), for which there is no cure. Here, statistical and machine learning (ML) models were developed to estimate the risk of site-specific DM following local-regional therapy. This retrospective study cohort included 175 patients diagnosed with invasive BC who later developed DM. Clinicopathological information was collected for analysis. Outcome variables were the first site of metastasis (brain, bone or visceral) and the time interval (months) to developing DM. Multivariate statistical analysis and ML-based multivariable gradient boosting machines identified factors associated with these outcomes. Machine learning models predicted the site of DM, demonstrating an area under the curve of 0.74, 0.75, and 0.73 for brain, bone and visceral sites, respectively. Overall, most patients (57%) developed bone metastases, with increased odds associated with estrogen receptor (ER) positivity. Human epidermal growth factor receptor-2 (HER2) positivity and non-anthracycline chemotherapy regimens were associated with a decreased risk of bone DM, while brain metastasis was associated with ER-negativity. Furthermore, non-anthracycline chemotherapy alone was a significant predictor of visceral metastasis. Here, clinicopathologic and treatment variables used in ML prediction models predict the first site of metastasis in BC. Further validation may guide focused patient-specific surveillance practices.

Patterns of treatment and outcomes of patients with brain-only metastatic breast cancer.

BACKGROUND: We characterized the risk factors and survival of metastatic breast cancer (MBC) patients with brain metastases (BrM) as the first and only site of disease in a large, retrospective cohort. METHODS: MBC patients treated for BrM with radiation at a quaternary institution between 2005 and 2019 were identified. MBC patients with BrM but without concurrent extracranial metastases (ECM) or leptomeningeal disease (LMD) were classified as brain-only. Factors associated with brain-only MBC, brain-specific progression free survival (bsPFS) and overall survival (OS) were investigated. RESULTS: A total of 691 patients with MBC and BrM were analyzed. Among them, 67 patients (9.7%, n = 67/691) presented with brain-only MBC without concurrent ECM/LMD. Within this subgroup, 40 patients (5.8%, n = 40/691) remained free of any ECM or LMD, while 17 patients (2.5%) developed LMD, and 10 patients (1.4%%) developed ECM with a median follow-up of 8 months (IQR 2-35). Patients with brain-only MBC were more likely to have a single BrM [OR 3.41 (1.62-7.19), p = 0.001] and either HER2+ [OR 3.3 (1.13-9.65), p = 0.03] or TNBC [OR 4.09 (1.42-11.74), p = 0.009] subtypes. Patients who presented with brain-only MBC also had significantly longer OS [HR 0.45, (0.22-0.86), p = 0.008] and a trend toward longer bsPFS [HR 0.67 (0.44-1.03), p = 0.05] compared to those with concurrent ECM/LMD. CONCLUSION: Patients with brain-only MBC had a longer bsPFS and OS than those with ECM. Patients with HER2+ and TNBC were more likely to have brain-only disease compared to those with HR+/HER2- MBC.

The Effectiveness and Safety of Stereotactic Body Radiation Therapy (SBRT) in the Treatment of Oligoprogressive Breast Cancer: A Systematic Review.

Stereotactic body radiotherapy (SBRT) has emerged as a technique to treat oligoprogressive sites among patients with breast cancer who are otherwise doing well on systemic therapy. This study systematically reviewed the efficacy and safety of SBRT in the setting of oligoprogressive breast cancer. A literature search was conducted in the MEDLINE database. Studies regarding SBRT and oligoprogressive breast cancer were included. Key outcomes of interest were toxicity, local control, progression, and overall survival. From 863 references, five retrospective single-center cohort studies were identified. All studies included patients with both oligometastatic and oligoprogressive disease; 112 patients with oligoprogressive breast cancer were identified across these studies. Patient age ranged from 22 to 84, with a median of 55 years of age. Most patients had hormone-receptor-positive and HER2-negative disease. SBRT doses varied from 24 to 60 Gy in 1-10 fractions based on the location/size of the lesion. Forty toxicity events were reported, of which the majority (n = 25, 62.5%) were grade 1-2 events. Among 15 patients who received SBRT concurrently with a CDK4/6 inhibitor, 37.5% of patients experienced grade 3-5 toxicities. Progression-free and overall survival ranged from 17 to 57% and 62 to 91%, respectively. There are limited data on the role of SBRT in oligoprogressive breast cancer, and prospective evaluation of this strategy is awaited to inform its safety and efficacy.

Poor Outcome in Postpartum Breast Cancer Patients Is Associated with Distinct Molecular and Immunologic Features.

PURPOSE: Patients with postpartum breast cancer diagnosed after cessation of breastfeeding (postweaning, PP-BCPW) have a particularly poor prognosis compared with patients diagnosed during lactation (PP-BCDL), or to pregnant (Pr-BC) and nulliparous (NP-BC) patients, regardless of standard prognostic characteristics. Animal studies point to a role of the involution process in stimulation of tumor growth in the mammary gland. However, in women, the molecular mechanisms that underlie this poor prognosis of patients with PP-BCPW remain vastly underexplored, due to of lack of adequate patient numbers and outcome data. EXPERIMENTAL DESIGN: We explored whether distinct prognostic features, common to all breast cancer molecular subtypes, exist in postpartum tumor tissue. Using detailed breastfeeding data, we delineated the postweaning period in PP-BC as a surrogate for mammary gland involution and performed whole transcriptome sequencing, immunohistochemical, and (multiplex) immunofluorescent analyses on tumor tissue of patients with PP-BCPW, PP-BCDL, Pr-BC, and NP-BC. RESULTS: We found that patients with PP-BCPW having a low expression level of an immunoglobulin gene signature, but high infiltration of plasma B cells, have an increased risk for metastasis and death. Although PP-BCPW tumor tissue was also characterized by an increase in CD8+ cytotoxic T cells and reduced distance among these cell types, these parameters were not associated with differential clinical outcomes among groups. CONCLUSIONS: These data point to the importance of plasma B cells in the postweaning mammary tumor microenvironment regarding the poor prognosis of PP-BCPW patients. Future prospective and in-depth research needs to further explore the role of B-cell immunobiology in this specific group of young patients with breast cancer.

Androgen Receptor Is Expressed in the Majority of Breast Cancer Brain Metastases and Is Subtype-Dependent.

We aimed to evaluate the expression of the "targetable" androgen receptor (AR) in breast cancer brain metastases (BrM). An established, retrospective 57-patient cohort with metastatic breast cancer who underwent surgery for BrM at the Sunnybrook Odette Cancer Centre between 1999-2013 was studied. AR expression in BrM samples was assessed in triplicate using immunohistochemistry (IHC). AR positive status was defined as nuclear AR expression ≥ 10% by IHC using the SP107 antibody. The median age of patients was 52 years (range 32-85 years). 28 (49%) of BrM were HER2+, 17 (30%) were hormone receptor positive (HR+)/HER2-, and 12 (21%) were triple negative breast cancers (TNBCs). 56% (n = 32/57) of BrM were AR positive, and median AR expression was 20% (CI 1.6-38.3%). AR expression was different across breast cancer subtypes; AR was most frequently expressed in HER2+ (n = 21/28), followed by HR+/HER2- (n = 9/17), and lowest in TNBC (n = 2/12) BrM (p = 0.003). Patients with AR positive versus AR negative BrM had similar overall survival (12.5 vs. 7.9 months, p = 0.6), brain-specific progression-free survival (8.0 vs. 5.1 months, p = 0.95), and time from breast cancer diagnosis to BrM diagnosis (51 vs. 29 months, p = 0.16). AR is expressed in the majority of breast cancer BrM and represents a potential therapeutic target.

Impact of non-adherence to endocrine therapy on recurrence risk in older women with stage I breast cancer after breast-conserving surgery.

PURPOSE: We examined the impact of non-adherence to adjuvant endocrine therapy (ET) on the risk and site of recurrence among older women with early stage, hormone receptor positive (HR+) breast cancer (EBC). METHODS: A population-based cohort of women age ≥ 65 years with T1N0 HR + EBC who were diagnosed between 2010 and 2016 and treated with breast-conserving surgery (BCS) + ET was identified. Treatment and outcomes were ascertained through linkage with administrative databases. ET non-adherence was examined as a time-dependent covariate in multivariable cause-specific Cox regression models to evaluate its effect on the risks of ipsilateral local recurrence (LR), contralateral breast cancer, and distant metastases. RESULTS: The population cohort includes 2637 women; 73% (N = 1934) received radiation (RT) + ET and 27% (N = 703) received ET alone. At a median follow-up of 8.14 years, the first event was LR in 3.6% of women treated with ET alone and 1.4% for those treated with RT + ET (p < 0.001); the risk of distant metastases was < 1% in both groups. The proportion of time adherent to ET was 69.0% among those treated with RT + ET and 62.8% for those treated with ET alone. On multivariable analysis, increasing proportion of time non-adherent to ET was associated with increased risk of LR ((HR = 1.52 per 20% increase in time; 95%CI 1.25, 1.85; p < 0.001), contralateral BC (HR = 1.55; 95%CI 1.30, 1.84; p < 0.001), and distant metastases (HR = 1.44; 95%CI 1.08, 1.94; p = 0.01) but absolute risks were low. CONCLUSION: Non-adherence to adjuvant ET was associated with an increased risk of recurrence, but absolute recurrence rates were low.

HR+/HER2- Advanced Breast Cancer Treatment in the First-Line Setting: Expert Review.

The approval of CDK4/6 inhibitors has dramatically improved care for the treatment of HR+/HER2- advanced breast cancer, but navigating the rapidly-expanding treatment evidence base is challenging. In this narrative review, we provide best-practice recommendations for the first-line treatment of HR+/HER2- advanced breast cancer in Canada based on relevant literature, clinical guidelines, and our own clinical experience. Due to statistically significant improvements in overall survival and progression-free survival, ribociclib + aromatase inhibitor is our preferred first-line treatment for de novo advanced disease or relapse ≥12 months after completion of adjuvant endocrine therapy and ribociclib or abemaciclib + fulvestrant is our preferred first-line treatment for patients experiencing early relapse. Abemaciclib or palbociclib may be used when alternatives to ribociclib are needed, and endocrine therapy can be used alone in the case of contraindication to CDK4/6 inhibitors or limited life expectancy. Considerations for special populations-including frail and fit elderly patients, as well as those with visceral disease, brain metastases, and oligometastatic disease-are also explored. For monitoring, we recommend an approach across CDK4/6 inhibitors. For mutational testing, we recommend routinely performing ER/PR/HER2 testing to confirm the subtype of advanced disease at the time of progression and to consider ESR1 and PIK3CA testing for select patients. Where possible, engage a multidisciplinary care team to apply evidence in a patient-centric manner.

Assessment of Phase 3 Randomized Clinical Trials Including Patients With Leptomeningeal Disease: A Systematic Review.

This systematic review examines the proportion of patients with leptomeningeal disease included in phase 3 randomized clinical trials for patients with metastatic breast cancer, lung cancer, and melanoma.

Association of Brain Metastases With Survival in Patients With Limited or Stable Extracranial Disease: A Systematic Review and Meta-analysis.

Importance: Intracranial metastatic disease (IMD) is a severe complication of cancer with profound prognostic implications. Patients with IMD in the setting of limited or stable extracranial disease (IMD-SE) may represent a unique and understudied subset of patients with IMD with superior prognosis. Objective: To evaluate overall survival (OS), progression-free survival (PFS), and intracranial PFS (iPFS) in patients with IMD-SE secondary to any primary cancer. Data Sources: Records were identified from MEDLINE, EMBASE, CENTRAL, and gray literature sources from inception to June 21, 2021. Study Selection: Studies in English reporting OS, PFS, or iPFS in patients with IMD-SE (defined as IMD and ≤2 extracranial metastatic sites) and no prior second-line chemotherapy or brain-directed therapy were selected. Data Extraction and Synthesis: Author, year of publication, type of study, type of primary cancer, and outcome measures were extracted. Random-effects meta-analyses were performed to estimate effect sizes, and subgroup meta-analysis and metaregression were conducted to measure between-study differences in February 2022. Main Outcomes and Measures: The primary end point was OS described as hazard ratios (HRs) and medians for comparative and single-group studies, respectively. Secondary end points were PFS and iPFS. Results: Overall, 68 studies (5325 patients) were included. IMD-SE was associated with longer OS (HR, 0.52; 95% CI, 0.39-0.70) and iPFS (HR, 0.63; 95% CI, 0.52-0.76) compared with IMD in the setting of progressive extracranial disease. The weighted median OS estimate for patients with IMD-SE was 17.9 months (95% CI, 16.4-22.0 months), and for patients with IMD-PE it was 8.0 months (95% CI, 7.2-12.8 months). Pooled median OS for all patients with IMD-SE was 20.9 months (95% CI, 16.35-25.98 months); for the subgroup with breast cancer it was 20.2 months (95% CI, 10.43-38.20 months), and for non-small cell lung cancer it was 27.5 months (95% CI, 18.27-49.66 months). Between-study heterogeneity for OS and iPFS were moderate (I2 = 56.5%) and low (I2 = 0%), respectively. Conclusions and Relevance: In this systematic review and meta-analysis of patients with IMD-SE, limited systemic disease was associated with improved OS and iPFS. Future prospective trials should aim to collect granular information on the extent of extracranial disease to identify drivers of mortality and optimal treatment strategies in patients with brain metastases.

Low Rates of Medical Oncology Consultation for Older Women (≥ 70 Years) with Newly Diagnosed, Non-Metastatic Breast Cancer: A Population-Based Study.

BACKGROUND: Curative intent cancer treatment needs to be balanced with patient comorbidities and quality of life when treating older women with breast cancer. We examined consultation patterns and association of age at diagnosis with lack of specialist cancer consultations for older women with breast cancer. METHODS: We conducted a population-based retrospective cohort study of older women (≥ 70 years of age) with incident, non-metastatic breast cancer (2010-2018) by linking administrative databases in Ontario, Canada. The outcomes of interest were lack of specialist cancer consultation (surgeon, medical oncology, or radiation oncology) within 12 months of diagnosis. Association of age with lack of specialist cancer consultation was examined using Poisson regression modeling. RESULTS: Of 21,849 older women, 2.4% (n = 517) did not have any specialist cancer consultation within 12 months of diagnosis; lack of any specialist cancer consultation increased with age (0.8% for age 70-74 years, 1.3% for age 75-79 years, 2.5% for age 80-84 years, and 7.0% for age ≥ 85 years; p < 0.001). The proportion of patients who did not have consultations with surgeons, medical oncologists, and radiation oncologists was 8.6% (n = 1888), 34.4% (n = 7510), and 24.7% (n = 5404), respectively. Older age group was independently associated with an increased likelihood of lacking any specialist consultation, as well as not receiving surgical and medical oncology consultations. CONCLUSION: More than one-third of women ≥ 70 years of age with non-metastatic breast cancer did not have a consultation with a medical oncologist, with women aged ≥ 85 years least likely to have a medical oncology consultation.