Excess mortality in postmenopausal high-risk women who only receive adjuvant endocrine therapy for estrogen receptor positive breast cancer

Outcomes based on risk-adapted adjuvant therapy in postmenopausal women with early breast cancer: a nationwide, prospective cohort study by the Danish Breast Cancer Group

BACKGROUND

Clinical prediction models are increasingly used to guide treatment in patients with early breast cancer. The Danish Breast Cancer Group (DBCG) has developed a prognostic standard mortality rate index (PSI) for prediction of excess mortality based on 5 years of endocrine therapy. In this study, we aimed to evaluate the clinical utility of the PSI.

METHODS

In this nationwide, prospective cohort study, we included postmenopausal Danish women aged 50 years or older with invasive oestrogen receptor-positive and HER2-negative resected breast cancer registered in the DBCG clinical database (close to all Danish women newly diagnosed with invasive breast cancer are registered in the national database). All participants were assigned a PSI category. Patients in the PSI 1 category were recommended 5 years of endocrine therapy; patients in PSI 2, 3, or 4 category were recommended endocrine therapy plus adjuvant chemotherapy according to Danish national guidelines. The primary endpoint was standard mortality ratio. Univariable and multivariable analyses for standard mortality ratio, overall survival, and recurrence-free survival were performed applying Kaplan-Meier, cumulative incidence, Poisson regression, and Fine-Gray subdistribution hazards model.

FINDINGS

25 027 women diagnosed with breast cancer between Aug 1, 2013, and Dec 31, 2018, and registered with the DBCG clinical database were identified. 8921 of those registered were eligible, assigned a PSI category (6704 [75%] PSI 1, 1300 [15%] PSI 2, 745 [8%] PSI 3, and 172 [2%] PSI 4), and included in the study. 8514 [96%] of 8830 women initiated endocrine therapy and 91 had an unknown therapy status. Adherence at 4·5 years was 67·8% (66·6-69·0) in the PSI 1 group and 72·3% (70·5-74·3) in the PSI 2-4 groups. Crude standard mortality ratio was 0·89 (95% CI 0·85-0·95) with PSI 1, 1·71 (95% CI 1·47-1·97) with PSI 2, and 2·39 (95% CI 1·99-2·88) with PSI 3-4. Compared with patients who completed adjuvant therapy with PSI 1, relative risk (RR) for excess mortality was 1·33 (95% CI 1·01-1·76) for patients with PSI 2 whereas patients with PSI 3-4 retained an excess mortality (RR 2·31, 95% CI 1·74-3·05) even with completed therapy.

INTERPRETATION

These data validate the clinical use of the PSI tool for risk adapted treatment allocation. In patients with PSI 1, the omission of chemotherapy was not associated with excess mortality overall and a distinct better outcome was seen in patients with completed endocrine therapy versus those who had not completed. With completed adjuvant therapy, excess mortality was low for patients with PSI 2, whereas patients with PSI 3-4 had high excess mortality, potentially warranting intensified treatment and requiring further investigation.

FUNDING

None.

Axillary clearance and chemotherapy rates in ER+HER2- breast cancer: secondary analysis of the SENOMAC trial

Background

Randomized trials have shown that axillary clearance (AC) can safely be omitted in patients with sentinel lymph node-positive breast cancer. At the same time, de-escalation of chemotherapy in postmenopausal patients with ER+HER2- breast cancer may depend on detailed axillary nodal stage. The aim of this pre-specified secondary analysis of the SENOMAC trial was to investigate whether the choice of axillary staging affected the proportion of patients receiving adjuvant chemotherapy, and recurrence-free survival (RFS).

Methods

Proportion receiving adjuvant chemotherapy was calculated according to AC or sentinel lymph node biopsy (SLNB) only, menopausal status, and region of inclusion, for 2168 patients with clinically node-negative ER+HER2- breast cancer and 1-2 sentinel lymph node macrometastases included in the SENOMAC trial.

Findings

In premenopausal patients, 514 out of 615 patients (83.6%) received adjuvant chemotherapy with no significant difference between randomization arms. In postmenopausal patients, the proportion receiving chemotherapy varied considerably by region and country (36.0-82.4%). In Denmark, where 194 out of 539 postmenopausal patients (36.0%) received adjuvant chemotherapy, rates differed significantly between the AC and the SLNB only arm (41.3% vs 31.4%, p = 0.019). After a median follow-up of 44.88 months for Danish postmenopausal patients, no significant difference was seen in 5-year RFS, which was 91% (85.6%-96.6%) for the SLNB only and 90.9% (86.3%-95.6%) for the AC arm (p = 0.42).

Interpretation

When omitting axillary clearance, and thus reducing the risk of long-term arm morbidity, potential under-treatment of postmenopausal patients with ER+HER2- breast cancer may require the development of new predictive and imaging tools.

Funding

Swedish Research Council, Swedish Cancer Society, Nordic Cancer Union, Swedish Breast Cancer Association.

Social Characteristics and Adherence to Adjuvant Endocrine Therapy in Premenopausal Women With Breast Cancer

PURPOSESocial characteristics, including cohabitation/marital status and socioeconomic position (SEP)-education level, employment status, and income-influence breast cancer prognosis. We investigated the impact of these social characteristics on adherence to adjuvant endocrine therapy (AET) from treatment initiation to 5 years after diagnosis.METHODSWe assembled a nationwide, population-based cohort of premenopausal women diagnosed in Denmark with stage I-III, estrogen receptor-positive breast cancer during 2002-2011. We ascertained prediagnostic social characteristics from national registries. AET adherence was based on information from the Danish Breast Cancer Group and operationalized as (1) adherence trajectories (from group-based trajectory modeling) and (2) early discontinuation. We computed odds ratios (ORs) and associated 95% CI to estimate the association of cohabitation and SEP with AET adherence using multinomial and logistic regression models adjusted according to directed acyclic graphs.RESULTSAmong 4,353 patients, we identified three adherence trajectories-high adherence (57%), slow decline (36%), and rapid decline (6.9%). Compared with cohabiting women, those living alone had higher ORs of slow (1.26 [95% CI, 1.08 to 1.46]) or rapid decline (1.66 [95% CI, 1.27 to 2.18]) versus high adherence. The corresponding ORs for women not working versus employed women were 1.22 (95% CI, 1.02 to 1.45) and 1.76 (95% CI, 1.30 to 2.38). For early discontinuation (17%), the ORs were 1.48 (95% CI, 1.23 to 1.78) for living alone and 1.44 (95% CI, 1.17 to 1.78) for women not working.CONCLUSIONAdherence to AET was lower among women living alone or unemployed than cohabiting or employed women, respectively. These women may benefit from support programs to enhance AET adherence.

Size of Extranodal Extension in the Sentinel Lymph Node as a Predictor of Prognosis in Early-Stage Breast Cancer

INTRODUCTION

The presence of extranodal extension (ENE) in sentinel lymph nodes (SLNs) can predict non-SLN metastases in breast cancer (BC) patients; however, the prognostic relevance of its extent remains controversial. The purpose of this study was to examine the predictive role of ENE in SLNs measured by its widest dimension (WD), highest dimension (HD), and the WD/HD ratio for non-SLN involvement, overall, and disease-free survival (OS, DFS) in cT1-2N0 BC patients with positive SLNs.

MATERIALS AND METHODS

A total of 511 women with cT1-2N0 BC and positive SLNs undergoing axillary lymph node dissection were retrospectively enrolled. The associations of ENE's WD, HD, and WD/HD ratio with non-SLN metastases, 5-year OS, and DFS were established through a multivariable modeling approach.

RESULTS

SLNs were ENE-positive in 149 (29.16%) participants, and 133 (26.03%) had non-SLN metastases. During the median 60 (16-60)-month follow-up, 69 (13.50%) patients experienced recurrences, and 62 (12.13%) died. The numbers of SLNs, non-SLNs, and total axillary LNs involved differed between the ENE-negative and ENE-positive groups, as well as between the WD/HD ≤ 1.2 and WD/HD > 1.2 subgroups (all P-values were < .001). Multivariable analyses showed significant associations of the WD/HD ratio > 1.2 with non-SLN involvement, OS, and DFS (P-values were .003, < .001, and .005, respectively).

DISCUSSION

Despite no predictive value of ENE's WD and HD, the WD/HD ratio > 1.2 was an independent predictor of non-SLN involvement, mortality, and recurrence. ENE's WD/HD ratio could be a valuable indicator for cT1-2N0 BC individuals with positive SLNs for whom further axillary treatment may be beneficial.

Importance of endocrine treatment adherence and persistence in breast cancer survivorship: a systematic review

PURPOSE

Adjuvant endocrine treatment is essential for treating luminal subtypes of breast cancer, which constitute 75% of all breast malignancies. However, the detrimental side effects of treatment make it difficult for many patients to complete the guideline-required treatment. Such non-adherence may jeopardize the lifesaving ability of anti-estrogen therapy. In this systematic review, we aimed to assess the consequences of non-adherence and non-persistence from available studies meeting strict statistical and clinical criteria.

METHODS

A systematic literature search was performed using several databases, yielding identification of 2,026 studies. After strict selection, 14 studies were eligible for systematic review. The review included studies that examined endocrine treatment non-adherence (patients not taking treatment as prescribed) or non-persistence (patients stopping treatment prematurely), in terms of the effects on event-free survival or overall survival among women with non-metastatic breast cancer.

RESULTS

We identified 10 studies measuring the effects of endocrine treatment non-adherence and non-persistence on event-free survival. Of these studies, seven showed significantly poorer survival for the non-adherent or non-persistent patient groups, with hazard ratios (HRs) ranging from 1.39 (95% CI, 1.07 to 1.53) to 2.44 (95% CI, 1.89 to 3.14). We identified nine studies measuring the effects of endocrine treatment non-adherence and non-persistence on overall survival. Of these studies, seven demonstrated significantly reduced overall survival in the groups with non-adherence and non-persistence, with HRs ranging from 1.26 (95% CI, 1.11 to 1.43) to 2.18 (95% CI, 1.99 to 2.39).

CONCLUSION

The present systematic review demonstrates that non-adherence and non-persistence to endocrine treatment negatively affect event-free and overall survival. Improved follow-up, with focus on adherence and persistence, is vital for improving health outcomes among patients with non-metastatic breast cancer.

Systemic or Vaginal Hormone Therapy After Early Breast Cancer: A Danish Observational Cohort Study

BACKGROUND

Women treated for breast cancer (BC) often suffer genitourinary syndrome of menopause. These symptoms may be alleviated by vaginal estrogen therapy (VET) or menopausal hormone therapy (MHT). However, there are concerns of risks of recurrence of BC and death following treatment.

METHODS

Our study included longitudinal data from a national cohort of postmenopausal women, diagnosed 1997-2004 with early-stage invasive estrogen receptor-positive nonmetastatic BC, who received no treatment or 5 years of adjuvant endocrine therapy. We ascertained prescription data on hormone therapy, VET or MHT, from a national prescription registry. We evaluated mortality and risk of recurrence associated with use of VET and MHT vs non-use using multivariable models adjusted for potential confounders.

RESULTS

Among 8461 women who had not received VET or MHT before BC diagnosis, 1957 and 133 used VET and MHT, respectively, after diagnosis. Median follow-up was 9.8 years for recurrence and 15.2 years for mortality. The adjusted relative risk of recurrence was 1.08 (95% confidence interval [CI] = 0.89 to 1.32) for VET (1.39 [95% CI = 1.04 to 1.85 in the subgroup receiving adjuvant aromatase inhibitors]) and 1.05 (95% CI = 0.62 to 1.78) for MHT. The adjusted hazard ratios for overall mortality were 0.78 (95% CI = 0.71 to 0.87) and 0.94 (95% CI = 0.70 to 1.26) for VET and MHT, respectively.

CONCLUSIONS

In postmenopausal women treated for early-stage estrogen receptor-positive BC, neither VET nor MHT was associated with increased risk of recurrence or mortality. A subgroup analysis revealed an increased risk of recurrence, but not mortality, in patients receiving VET with adjuvant aromatase inhibitors.

Socioeconomic position and prognosis in premenopausal breast cancer: a population-based cohort study in Denmark

BACKGROUND

To investigate how socioeconomic position (SEP) influences the effectiveness of cancer-directed treatment in premenopausal breast cancer patients in terms of breast cancer recurrence and mortality.

METHODS

We conducted a cohort study nested in the ProBeCaRe (Predictors of Breast Cancer Recurrence) cohort (n = 5959). We identified all premenopausal women aged 18-55 years diagnosed with non-metastatic breast cancer and prescribed docetaxel-based chemotherapy in Denmark during 2007-2011. Population-based administrative registries provided data on SEP: marital status (married including registered partnership or single including divorced or widowed), cohabitation (cohabiting or living alone), education (low, intermediate, or high), income (low, medium, or high), and employment status (employed, unemployed, or health-related absenteeism). For each SEP measure, we computed incidence rates, cumulative incidence proportions (CIPs), and used Poisson regression to compute incidence rate ratios (IRRs) and 95% confidence intervals (CIs) of recurrence and death. We stratified on estrogen receptor (ER) status/tamoxifen to evaluate interaction.

RESULTS

Our study cohort included 2616 women; 286 (CIP 13%) experienced recurrence and 223 (CIP 11%) died during follow-up (median 6.6 and 7.2 years, respectively). Single women had both increased 5-year risks of recurrence (IRR 1.45, 95% CI 1.11-1.89) and mortality (IRR 1.83, 95% CI 1.32-2.52). Furthermore, we observed increased 5-year mortality in women with low education (IRR 1.49, 95% CI 0.95-2.33), low income (IRR 1.37, 95% CI 0.83-2.28), unemployment (IRR 1.61, 95% CI 0.83-3.13), or health-related work absenteeism (IRR 1.80, 95% CI 1.14-2.82), but smaller or no increased risk of recurrence. These findings were especially evident among women with ER+ tumors prescribed tamoxifen. Overall analyses (follow-up max. 10 years) provided similar results.

CONCLUSIONS

Low SEP in premenopausal women with non-metastatic breast cancer was associated with increased mortality, but not always recurrence. This suggests underdetection of recurrences in certain groups. Poor prognosis in women with low SEP, especially single women, may partly be explained by tamoxifen adherence.

Systematic review of real-world studies evaluating the impact of medication non-adherence to endocrine therapies on hard clinical endpoints in patients with non-metastatic breast cancer

Breast cancer, one of the most common malignancies, is associated with significant economic and health burden both at the patient and societal level. Although medication non-adherence to endocrine breast cancer therapies is common, so far only limited systematic evidence has been available on its quantitative consequences, as previous systematic reviews focused mainly on factors contributing to medication non-adherence. The objective of this review was to explore the implications of medication non-adherence to endocrine therapies on hard clinical outcomes in breast cancer based on real-world studies. A systematic literature review was conducted on PubMed; empirical evidence on hard clinical endpoints (i.e., survival, disease-free survival, metastasis and recurrence) were extracted from uni- or multivariate statistical analyses from retrospective or prospective cohort studies. Of the 2,360 identified records, 12 studies met the inclusion criteria. Two studies identified significant positive association between medication non-adherence and the risk of distant metastasis, three articles between medication non-adherence and the recurrence of breast cancer, two studies between medication non-adherence- and non-persistence and of worse disease-free survival and eight articles between medication non-adherence and mortality. There was only one study where the positive association between medication adherence and survival did not apply to all subgroups. The strong evidence on the negative health consequences of non-adherence to breast cancer treatments indicates the need for the regular monitoring of medication adherence. Furthermore, explicit inclusion of adherence enhancing interventions into health policy agenda would be warranted to improve medication adherence also at a system level.

Early Discontinuation of Endocrine Therapy and Recurrence of Breast Cancer among Premenopausal Women

PURPOSE

Premenopausal women diagnosed with estrogen receptor (ER)-positive breast cancer are prescribed 5-10 years of endocrine therapy to prevent or delay recurrence. In this study, we evaluated the association between early discontinuation of endocrine therapy and breast cancer recurrence in a cohort of premenopausal women.

EXPERIMENTAL DESIGN

We identified 4,503 patients with premenopausal ER-positive breast cancer who initiated adjuvant endocrine therapy and were registered in the Danish Breast Cancer Group clinical database (2002-2011). Women were excluded if they had a recurrence or were lost to follow-up less than 1.5 years after breast cancer surgery. Endocrine therapy was considered complete if the patient received at least 4.5 years of treatment or discontinued medication less than 6 months before recurrence. Exposure status was updated annually and modeled as a time-dependent variable. We accounted for baseline and time-varying confounders via time-varying weights, which we calculated from multivariable logistic regression models, and included in regression models to estimate HRs and 95% confidence intervals (CIs) associating early discontinuation with recurrence.

RESULTS

Over the study follow-up, 1,001 (22%) women discontinued endocrine therapy. We observed 202 (20%) recurrences among those who discontinued endocrine therapy, and 388 (11%) among those who completed the recommended treatment. The multivariable-adjusted estimated rate of recurrence was higher in women who discontinued endocrine therapy relative to those who completed their treatment (hazard ratio, 1.67; 95% CI, 1.25-2.14).

CONCLUSIONS

These results highlight the importance of clinical follow-up and behavioral interventions that support persistence of adjuvant endocrine therapy to prevent breast cancer recurrence.

Adjuvant endocrine therapy is associated with improved overall survival in elderly hormone receptor-positive breast cancer patients

PURPOSE

There is controversy regarding the survival benefit of endocrine therapy (ET) in elderly patients with early invasive hormone receptor-positive (HR+) breast cancer. In this study, we characterize a single institution's practice patterns using adjuvant ET for these patients and evaluated the effect of ET on outcomes.

METHODS

A review of a prospectively maintained database identified 483 women ≥ 70 years old who underwent breast -conserving surgery (BCS) for stage I-III HR+ tumors from 2004-2013. We compared clinicopathologic characteristics, overall survival (OS), disease-free survival (DFS), locoregional recurrence (LRR), and breast cancer-specific survival (BCSS) in patients who did and did not receive ET.

RESULTS

Compared to patients who did not get ET, patients who received ET were younger (median age 76 vs 78 years, p = 0.006), had larger tumors (median size 15 vs 14 mm, p = 0.016), underwent sentinel lymph node (LN) biopsy (83.7 vs 67.8%, p < 0.001), had positive LNs (25.5 vs 9.8%, p = 0.008), and received radiation (XRT, 76 vs 43%, p < 0.001). After adjusting for ASA score, age, LN status, tumor grade, and XRT, receipt of ET was associated with improved OS (HR 0.44; 95% CI 0.25-0.77; p = 0.004) and DFS (HR 0.42; 95% CI 0.28-0.64; p < 0.01). Receipt of ET was associated with improved LRR on univariate analysis (HR 0.25; 95% CI 0.09-0.70; p = 0.008); however, after adjusting for grade and XRT, this was not statistically significant on multivariable analysis (HR 0.38; 95% CI 0.13-1.08; p = 0.069) and was not associated with BCSS (HR 0.59; 95% CI 0.16-2.16; p = 0.43).

CONCLUSIONS

ET was associated with significant improvements in OS and DFS, regardless of clinicopathological features; however, receipt of ET did not impact LRR and BCSS.

Population-based Study of Prosigna-PAM50 and Outcome Among Postmenopausal Women With Estrogen Receptor-positive and HER2-negative Operable Invasive Lobular or Ductal Breast Cancer

PURPOSE

The Prosigna-PAM50 risk of recurrence (ROR) score has documented clinical utility for the prediction of 10-year distant recurrence (DR). The present study investigated the value of Prosigna-PAM50 for predicting 10-year DR and overall survival after 5 years of endocrine treatment for postmenopausal patients with invasive lobular carcinoma.

PATIENTS AND METHODS

Using the Danish Breast Cancer Group database, we identified patients with a diagnosis from 2000 to 2003 of estrogen receptor-positive, human epidermal growth factor receptor 2-negative invasive ductal (n = 1570) or lobular (n = 341) cancer > 20 mm or 1 to 3 positive lymph nodes and applied multivariate Cox models.

RESULTS

The median follow-up for DR was 9.3 years and for overall survival 15.2 years. Of the 341 lobular and 1570 ductal cases, 140 (41%) and 349 (22%) were classified as low ROR, with a 10-year DR rate of 7.7% (95% confidence interval [CI], 3.7%-13.6%) and 3.5% (95% CI, 1.8%-6.2%), respectively. The 10-year DR rate for the intermediate ROR group for those with lobular cancer was 18% (95% CI, 10.1%-27.9%) compared with 9.7% (95% CI, 6.7%-13.4%) for those with ductal cancer. Luminal B tumors had a significantly worse outcome than luminal A tumors in both lobular (hazard ratio, 1.89; 95% CI, 1.03%-3.45%; P = .04) and ductal (hazard ratio, 3.18; 95% CI, 2.29%-4.43%; P < .0001) cancer.

CONCLUSION

Prosigna PAM-50 provides significant prognostic information beyond the clinicopathologic factors in patients with invasive lobular breast cancer. Those with lobular cancer had worse 10-year DR rates compared with those with ductal cancer in the same ROR category. Our results could have an effect on the treatment decisions regarding the addition of chemotherapy for those in the intermediate ROR group.

Whole genome sequencing of breast cancer

Breast cancer was the first to take advantage of targeted therapy using endocrine therapy, and for up to 20% of all breast cancer patients a further significant improvement has been obtained by HER2‐targeted therapy. Greater insight in precision medicine is to some extent driven by technical and computational progress, with the first wave of a true technical advancement being the application of transcriptomic analysis. Molecular subtyping further improved our understanding of breast cancer biology and has through a new tumor classification enabled allocation of personalized treatment regimens. The next wave in technical progression must be next‐generation‐sequencing which is currently providing new and exciting results. Large‐scale sequencing data unravel novel somatic and potential targetable mutations as well as allowing the identification of new candidate genes predisposing for familial breast cancer. So far, around 15% of all breast cancer patients are genetically predisposed with most genes being factors in pathways implicated in genome maintenance. This review focuses on whole‐genome sequencing and the new possibilities that this technique, together with other high‐throughput analytic approaches, provides for a more individualized treatment course of breast cancer patients.

Non-linear transformations of age at diagnosis, tumor size, and number of positive lymph nodes in prediction of clinical outcome in breast cancer

BACKGROUND

Prognostic factors in breast cancer are often measured on a continuous scale, but categorized for clinical decision-making. The primary aim of this study was to evaluate if accounting for continuous non-linear effects of the three factors age at diagnosis, tumor size, and number of positive lymph nodes improves prognostication. These factors will most likely be included in the management of breast cancer patients also in the future, after an expected implementation of gene expression profiling for adjuvant treatment decision-making.

METHODS

Four thousand four hundred forty seven and 1132 women with primary breast cancer constituted the derivation and validation set, respectively. Potential non-linear effects on the log hazard of distant recurrences of the three factors were evaluated during 10 years of follow-up. Cox-models of successively increasing complexity: dichotomized predictors, predictors categorized into three or four groups, and predictors transformed using fractional polynomials (FPs) or restricted cubic splines (RCS), were used. Predictive performance was evaluated by Harrell's C-index.

RESULTS

Using FP-transformations, non-linear effects were detected for tumor size and number of positive lymph nodes in univariable analyses. For age, non-linear transformations did, however, not improve the model fit significantly compared to the linear identity transformation. As expected, the C-index increased with increasing model complexity for multivariable models including the three factors. By allowing more than one cut-point per factor, the C-index increased from 0.628 to 0.674. The additional gain, as measured by the C-index, when using FP- or RCS-transformations was modest (0.695 and 0.696, respectively). The corresponding C-indices for these four models in the validation set, based on the same transformations and parameter estimates from the derivation set, were 0.675, 0.700, 0.706, and 0.701.

CONCLUSIONS

Categorization of each factor into three to four groups was found to improve prognostication compared to dichotomization. The additional gain by allowing continuous non-linear effects modeled by FPs or RCS was modest. However, the continuous nature of these transformations has the advantage of making it possible to form risk groups of any size.

PAM50 Risk of Recurrence Score Predicts 10-Year Distant Recurrence in a Comprehensive Danish Cohort of Postmenopausal Women Allocated to 5 Years of Endocrine Therapy for Hormone Receptor–Positive Early Breast Cancer

Purpose

The PAM50-based Prosigna risk of recurrence (ROR) score has been validated in randomized clinical trials to predict 10-year distant recurrence (DR). The value of Prosigna for predicting DR was examined in a comprehensive nationwide Danish cohort consisting of postmenopausal women with hormone receptor–positive early breast cancer treated with 5 years of endocrine therapy alone.

Patients and Methods

Using the population-based Danish Breast Cancer Cooperative Group database, follow-up data were collected on all patients diagnosed from 2000 through 2003 who, by nationwide guidelines, were treated with endocrine therapy for 5 years. Primary tumor blocks from 2,740 patients were tested with Prosigna and, after determination of human epidermal growth factor receptor 2 (HER2) status, data from 2,558 hormone receptor–positive/HER2-negative samples were analyzed, including 1,395 node-positive patients. Fine and Gray models were applied to determine the prognostic value of ROR for DR.

Results

Median follow-up for recurrence was 9.2 years. Twenty-six percent of the node-positive patients were classified as low ROR (n = 359) with a DR risk of 3.5% (95% confidence interval [CI], 1.9% to 6.1%) versus a DR risk of 22.1% (95% CI, 18.6% to 25.8%) at 10 years for patients classified as high ROR (n = 648). Node-negative patients classified as low and high ROR had a risk of DR of 5.0% (95% CI, 2.9% to 8.0%) and 17.8% (95% CI, 14.0% to 22.0%), respectively. Luminal B tumors (n = 947; DR risk, 18.4% [95% CI: 15.7% to 21.3%]) had a significantly worse outcome than luminal A tumors (n = 1,474,;DR risk, 7.6% [95% CI: 6.1% to 9.2%]; P < .001).

Conclusion

Prosigna ROR score improved the prediction of outcome in this nationwide Danish population. In a real-world setting, Prosigna can reliably identify node-negative patients and a significant proportion of patients with one to three positive nodes who can be spared treatment with adjuvant chemotherapy.

The ability of PAM50 risk of recurrence score to predict 10-year distant recurrence in hormone receptor-positive postmenopausal women with special histological subtypes

INTRODUCTION

The Prosigna-PAM50 risk of recurrence (ROR) score has been validated in randomized clinical trials to predict 10-year distant recurrence (DR) in hormone receptor-positive breast cancer. Here, we examine the ability of Prosigna for predicting DR at 10 years in a subgroup of postmenopausal breast cancer patients with special histological subtypes.

METHODS

Using the population based Danish Breast Cancer Group database, follow-up data were collected on all patients diagnosed from 2000 to 2003 with estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2) normal breast cancer who by nationwide guidelines were treated with 5 year of endocrine therapy (N = 2558). Among patients with 1 to 3 positive lymph nodes or a tumor size >20 mm, we identified 1570 with invasive ductal carcinoma (IDC) and 89 with special histological subtypes (apocrine, medullary, mucinous, papillary, secretory, tubular, neuroendocrine) who were tested with Prosigna. Fine and Gray models were applied to determine the prognostic value of the Prosigna-PAM50 ROR score for DR special subtypes as compared to IDC.

RESULTS

Median follow-up for DR was 9.2 year and for OS 15.2 year. The 10-year DR rate for the special subtypes was 9.2% (95% CI: 4.0% to 17.2%) as compared to 13.7% (95% CI: 11.9% to 15.7%) for IDC. The 10-year OS was 74.2% (95% CI: 63.7% to 82.0%) for the special subtypes and 75.4% (95% CI: 73.2% to 77.4%) for IDC. Prosigna showed a statistical significant association of the continuous ROR score with risk of DR for both IDC and the special subtypes (IDC: p < .0001; special subtypes: p = .01).

CONCLUSION

In the present study, we demonstrated that Prosigna-PAM50 continuous ROR score added significant prognostic information for 10-year DR in postmenopausal patients with special subtypes (tumor size >20 mm or 1 to 3 positive lymph nodes) and ER-positive, HER2-normal early breast cancer.

Molecular subtyping of breast cancer improves identification of both high and low risk patients

BACKGROUND

Transcriptome analysis enables classification of breast tumors into molecular subtypes that correlate with prognosis and effect of therapy. We evaluated the clinical benefits of molecular subtyping compared to our current diagnostic practice.

MATERIALS AND METHODS

Molecular subtyping was performed on a consecutive and unselected series of 524 tumors from women with primary breast cancer (n = 508). Tumors were classified by the 256 gene expression signature (CIT) and compared to conventional immunohistochemistry (IHC) procedures.

RESULTS

More than 99% of tumors were eligible for molecular classification and final reports were available prior to the multidisciplinary conference. Using a prognostic standard mortality rate index (PSMRi) developed by the Danish Breast Cancer Group (DBCG) 39 patients were assigned with an intermediate risk and among these 16 (41%) were furthermore diagnosed by the multi-gene signature assigned with a luminal A tumor and consequently spared adjuvant chemotherapy. There was overall agreement between mRNA derived and IHC hormone receptor status, whereas IHC Ki67 protein proliferative index proved inaccurate, compared to the mRNA derived index. Forty-one patients with basal-like (basL) subtypes were screened for predisposing mutations regardless of clinical predisposition. Of those 17% carried pathogenic mutations.

CONCLUSION

Transcriptome based subtyping of breast tumors evidently reduces the need for adjuvant chemotherapy and improves identification of women with predisposing mutations. The results imply that transcriptome profiling should become an integrated part of current breast cancer management.

Clinical and molecular characterization of BRCA-associated breast cancer: results from the DBCG

BACKGROUND

In breast cancer (BC) patients a cancer predisposing BRCA1/2 mutation is associated with adverse tumor characteristics, risk assessment and treatment allocation. We aimed to estimate overall- (OS) and disease-free survival (DFS) according to tumor characteristics and treatment among women who within two years of definitive surgery for primary BC were shown to carry a mutation in BRCA1/2 .

MATERIAL AND METHODS

From the clinical database of the Danish Breast Cancer Group we included 141 BRCA1 and 96 BRCA2 BC patients. Estrogen receptor and HER2 status were centrally reviewed on paraffin-embedded tumor tissue. Information on risk reducing surgery was obtained from the Danish Pathology and Patient Registries and included as time-dependent variables in Cox proportional hazard models.

RESULTS

Ten-year OS and DFS for BRCA1 BC patients were 78% (95% CI 69-85) and 74% (95% CI 64-81). Ten-year OS and DFS for BRCA2 BC were 88% (95% CI 78-94) and 84% (95% CI 74-91). BRCA1 BC patients as compared to BRCA2 BC patients had a higher risk of BC relapse or non-breast cancer within ten years of follow-up, independent of ER status (adjusted HR 2.78 95% CI 1.28-6.05, p = .01), but BRCA mutation was not associated with OS (adjusted HR 1.98, 95% CI 0.87-4.52, p = .10). In multivariate analysis, including both BRCA1 and BRCA2 carriers, no chemotherapy was associated with a higher risk of death (adjusted OS HR 3.58, 95% CI 1.29-9.97, p = .01) and risk reducing contralateral mastectomy (RRCM) was associated with a significantly reduced risk of death (adjusted OS HR 0.42, 95% CI =0.21-0.84, p = .01).

CONCLUSION

Difference in OS between BRCA1 and BRCA2 BC patients could be ascribed to tumor-biology. BRCA1 BC patients may have a shorter ten-year DFS than BRCA2 BC patients. Chemotherapy and risk reducing contralateral mastectomy reduce mortality for both BRCA1 and BRCA2 BC patients.

The clinical database and implementation of treatment guidelines by the Danish Breast Cancer Cooperative Group in 2007-2016

BACKGROUND

Since 40 years, Danish Breast Cancer Cooperative Group (DBCG) has provided comprehensive guidelines for diagnosis and treatment of breast cancer. This population-based analysis aimed to describe the plurality of modifications introduced over the past 10 years in the national Danish guidelines for the management of early breast cancer. By use of the clinical DBCG database we analyze the effectiveness of the implementation of guideline revisions in Denmark.

METHODS

From the DBCG guidelines we extracted modifications introduced in 2007-2016 and selected examples regarding surgery, radiotherapy (RT) and systemic treatment. We assessed introduction of modifications from release on the DBCG webpage to change in clinical practice using the DBCG clinical database.

RESULTS

Over a 10-year period data from 48,772 patients newly diagnosed with malignant breast tumors were entered into DBCG's clinical database and 42,197 of these patients were diagnosed with an invasive carcinoma following breast conserving surgery (BCS) or mastectomy. More than twenty modifications were introduced in the guidelines. Implementations, based on prospectively collected data, varied widely; exemplified with around one quarter of the patients not treated according to a specific guideline within one year from the introduction, to an almost immediate full implantation.

CONCLUSIONS

Modifications of the DBCG guidelines were generally well implemented, but the time to full implementation varied from less than one year up to around five years. Our data is registry based and does not allow a closer analysis of the causes for delay in implementation of guideline modifications.

A high level of estrogen-stimulated proteins selects breast cancer patients treated with adjuvant endocrine therapy with good prognosis

BACKGROUND

Adjuvant endocrine therapy has significantly improved survival of estrogen receptor α (ER)-positive breast cancer patients, but around 20% relapse within 10 years. High expression of ER-stimulated proteins like progesterone receptor (PR), Bcl-2 and insulin-like growth factor receptor I (IGF-IR) is a marker for estrogen-driven cell growth. Therefore, patients with high tumor levels of these proteins may have particularly good prognosis following adjuvant endocrine therapy.

PATIENTS AND METHODS

Archival tumor tissue was available from 1323 of 1396 Danish breast cancer patients enrolled in BIG 1-98, a randomized phase-III clinical trial comparing adjuvant letrozole, tamoxifen or a sequence of the two drugs. Immunohistochemical staining for ER, HER-2, PR, Bcl-2 and IGF-IR was performed and determined by Allred scoring (ER, PR and Bcl-2) or HercepTest (HER-2 and IGF-IR).

RESULTS

Data on all five markers were available from 969 patients with ER-positive, HER-2-negative tumors. These patients were classified in ER activity groups based on the level of PR, Bcl-2 and IGF-IR. High ER activity profile was found in 102 patients (10.5%) and compared with the remaining patients, univariate and multivariate analysis revealed HR (95% CI) and p values for disease-free survival (DFS) of 2.00 (1.20-3.22), 0.008 and 1.70 (1.01-2.84), 0.04 and for the overall survival (OS) of 2.33 (1.19-4.57), 0.01 and 1.90 (0.97-3.79), 0.06, respectively. The high ER activity profile did not disclose difference in DFS or OS according to treatment with tamoxifen or letrozole (p = .06 and .09, respectively).

CONCLUSIONS

Stratifying endocrine-treated patients in ER activity profile groups disclosed that patient with high ER activity profile (10.5%) had significantly longer DFS and OS, and the profile was an independent marker for DFS. High ER activity is a marker for estrogen-driven tumor growth. We suggest further analyses to disclose whether the ER activity profile or other markers associated with estrogen-driven growth may be used to identify ER-positive high-risk breast cancer patients who can be spared adjuvant chemotherapy.

Hormone receptor status of a first primary breast cancer predicts contralateral breast cancer risk in the WECARE study population

BACKGROUND

Previous population-based studies have described first primary breast cancer tumor characteristics and their association with contralateral breast cancer (CBC) risk. However, information on influential covariates such as treatment, family history of breast cancer, and BRCA1/2 mutation carrier status was not available. In a large, population-based, case-control study, we evaluated whether tumor characteristics of the first primary breast cancer are associated with risk of developing second primary asynchronous CBC, overall and in subgroups of interest, including among BRCA1/2 mutation non-carriers, women who are not treated with tamoxifen, and women without a breast cancer family history.

METHODS

The Women's Environmental Cancer and Radiation Epidemiology Study is a population-based case-control study of 1521 CBC cases and 2212 individually-matched controls with unilateral breast cancer. Detailed information about breast cancer risk factors, treatment for and characteristics of first tumors, including estrogen receptor (ER) and progesterone receptor (PR) status, was obtained by telephone interview and medical record abstraction. Multivariable risk ratios (RRs) and 95% confidence intervals (CIs) were estimated in conditional logistic regression models, adjusting for demographics, treatment, and personal medical and family history. A subset of women was screened for BRCA1/2 mutations.

RESULTS

Lobular histology of the first tumor was associated with a 30% increase in CBC risk (95% CI 1.0-1.6). Compared to women with ER+/PR+ first tumors, those with ER-/PR- tumors had increased risk of CBC (RR = 1.4, 95% CI 1.1-1.7). Notably, women with ER-/PR- first tumors were more likely to develop CBC with the ER-/PR- phenotype (RR = 5.4, 95% CI 3.0-9.5), and risk remained elevated in multiple subgroups: BRCA1/2 mutation non-carriers, women younger than 45 years of age, women without a breast cancer family history, and women who were not treated with tamoxifen.

CONCLUSIONS

Having a hormone receptor negative first primary breast cancer is associated with increased risk of CBC. Women with ER-/PR- primary tumors were more likely to develop ER-/PR- CBC, even after excluding BRCA1/2 mutation carriers. Hormone receptor status, which is routinely evaluated in breast tumors, may be used clinically to determine treatment protocols and identify patients who may benefit from increased surveillance for CBC.

Risk factors for delay of adjuvant chemotherapy in non-metastatic breast cancer patients: A systematic review and meta-analysis involving 186982 patients

Purpose

Delay performance of adjuvant chemotherapy (AC) after surgery has been presented to affect survival of breast cancer patients adversely, but the risk factors for delay in initiation remain controversial. Therefore, we conducted this systematic review of the literature and meta-analysis aiming at identifying the risk factors for delay of adjuvant chemotherapy (DAC) in non-metastatic breast cancer patients.

Methods

The search was performed on PubMed, Embase, Chinese National Knowledge Infrastructure and Wanfang Database from inception up to July 2016. DAC was defined as receiving AC beyond 8-week after surgery. Data were combined and analyzed using random-effects model or fixed-effects model for risk factors considered by at least 3 studies. Heterogeneity was analyzed with meta-regression analysis of year of publication and sample size. Publication bias was studied with Egger’s test.

Results

A total of 12 observational studies including 186982 non-metastatic breast cancer patients were eligible and 12 risk factors were analyzed. Combined results demonstrated that black race (vs white; OR, 1.18; 95% CI, 1.01–1.39), rural residents (vs urban; OR, 1.60; 95% CI, 1.27–2.03) and receiving mastectomy (vs breast conserving surgery; OR, 1.35; 95% CI, 1.00–1.83) were significantly associated with DAC, while married patients (vs single; OR, 0.58; 95% CI, 0.38–0.89) was less likely to have a delay in initiation. No significant impact from year of publication or sample size on the heterogeneity across studies was found, and no potential publication bias existed among the included studies.

Conclusions

Risk factors associated with DAC included black race, rural residents, receiving mastectomy and single status. Identifying of these risk factors could further help decisions making in clinical practice.

Cytochrome P-450 2D6 (CYP2D6) Genotype and Breast Cancer Recurrence in Tamoxifen-Treated Patients: Evaluating the Importance of Loss of Heterozygosity

Tamoxifen therapy for estrogen receptor-positive breast cancer reduces the risk of recurrence by approximately one-half. Cytochrome P-450 2D6, encoded by the polymorphic cytochrome P-450 2D6 gene (CYP2D6), oxidizes tamoxifen to its most active metabolites. Steady-state concentrations of endoxifen (4-hydroxy-N-desmethyltamoxifen), the most potent antiestrogenic metabolite, are reduced in women whose CYP2D6 genotypes confer poor enzyme function. Thirty-one studies of the association of CYP2D6 genotype with breast cancer survival have yielded heterogeneous results. Some influential studies genotyped DNA from tumor-infiltrated tissues, and their results may have been susceptible to germline genotype misclassification from loss of heterozygosity at the CYP2D6 locus. We systematically reviewed 6 studies of concordance between genotypes obtained from paired nonneoplastic and breast tumor-infiltrated tissues, all of which showed excellent CYP2D6 genotype agreement. We applied these concordance data to a quantitative bias analysis of the subset of the 31 studies that were based on genotypes from tumor-infiltrated tissue to examine whether genotyping errors substantially biased estimates of association. The bias analysis showed negligible bias by discordant genotypes. Summary estimates of association, with or without bias adjustment, indicated no clinically important association between CYP2D6 genotype and breast cancer survival in tamoxifen-treated women.

Danish Breast Cancer Cooperative Group

AIM OF DATABASE

Danish Breast Cancer Cooperative Group (DBCG), with an associated database, was introduced as a nationwide multidisciplinary group in 1977 with the ultimate aim to improve the prognosis in breast cancer. Since then, the database has registered women diagnosed with primary invasive nonmetastatic breast cancer. The data reported from the departments to the database included details of the characteristics of the primary tumor, of surgery, radiotherapy, and systemic therapies, and of follow-up reported on specific forms from the departments in question.

DESCRIPTIVE DATA

From 1977 through 2014, ~110,000 patients are registered in the nationwide, clinical database. The completeness has gradually improved to more than 95%. DBCG has continuously prepared evidence-based guidelines on diagnosis and treatment of breast cancer and conducted quality control studies to ascertain the degree of adherence to the guidelines in the different departments.

CONCLUSION

Utilizing data from the DBCG database, a long array of high-quality DBCG studies of various designs and scope, nationwide or in international collaboration, have contributed to the current updating of the guidelines, and have been an instrumental resource in the improvement of management and prognosis of breast cancer in Denmark. Thus, since the establishment of DBCG, the prognosis in breast cancer has continuously improved with a decrease in 5-year mortality from ~37% to 15%.

Improvements in breast cancer survival between 1995 and 2012 in Denmark: The importance of earlier diagnosis and adjuvant treatment

Background Breast cancer mortality has declined from 1995 through 2012 which may be attributed to earlier diagnosis, changes in lifestyle risk factors, and improved treatments. To a large extent the relative contribution of these modalities are unknown. Mammography screening was introduced late in Denmark; in 1995 around 20% of the Danish female population aged 50-69 was covered by population-based screening, and this was in 2008 extended to the entire population. Breast conserving surgery gradually replaced mastectomy, and sentinel node biopsy was introduced. In the same period adjuvant treatment was extended considerable. Methods A population-based study of 68 842 breast cancer patients registered in the clinical database of the Danish Breast Cancer Cooperative Group in 1995-2012. Comprehensive data on prognostic factors, comorbidity and treatment together with complete follow-up for survival were used to evaluate improvements in mortality and standardized mortality rate in successive time periods. Results The results from this study demonstrated a significant improvement in prognosis in successive time periods covering 1995-2012. Apart from patients with a high Charlson Comorbidity Index (CCI) improvements were seen in all subgroups of patients. Prognostic factors were more favorable in the latest time period accordingly to the introduction of nationwide screening. In the study period adjuvant treatment was extended considerable. Conclusion The impact of screening was by nature of limited magnitude. The modified treatment strategies implemented by the use of nationwide guidelines seemed to have a major impact on the substantial survival improvements.

Treatment Adherence and Its Impact on Disease-Free Survival in the Breast International Group 1-98 Trial of Tamoxifen and Letrozole, Alone and in Sequence

PURPOSE

To investigate adherence to endocrine treatment and its relationship with disease-free survival (DFS) in the Breast International Group (BIG) 1-98 clinical trial.

METHODS

The BIG 1-98 trial is a double-blind trial that randomly assigned 6,193 postmenopausal women with hormone receptor-positive early breast cancer in the four-arm option to 5 years of tamoxifen (Tam), letrozole (Let), or the agents in sequence (Let-Tam, Tam-Let). This analysis included 6,144 women who received at least one dose of study treatment. Conditional landmark analyses and marginal structural Cox proportional hazards models were used to evaluate the relationship between DFS and treatment adherence (persistence [duration] and compliance with dosage). Competing risks regression was used to assess demographic, disease, and treatment characteristics of the women who stopped treatment early because of adverse events.

RESULTS

Both aspects of low adherence (early cessation of letrozole and a compliance score of < 90%) were associated with reduced DFS (multivariable model hazard ratio, 1.45; 95% CI, 1.09 to 1.93; P = .01; and multivariable model hazard ratio, 1.61; 95% CI, 1.08 to 2.38; P = .02, respectively). Sequential treatments were associated with higher rates of nonpersistence (Tam-Let, 20.8%; Let-Tam, 20.3%; Tam 16.9%; Let 17.6%). Adverse events were the reason for most trial treatment early discontinuations (82.7%). Apart from sequential treatment assignment, reduced adherence was associated with older age, smoking, node negativity, or prior thromboembolic event.

CONCLUSION

Both persistence and compliance are associated with DFS. Toxicity management and, for sequential treatments, patient and physician awareness, may improve adherence.

Adjuvant endocrine therapy in pre- versus postmenopausal patients with steroid hormone receptor-positive breast cancer: results from a large population-based cohort of a cancer registry

PURPOSE

Adjuvant endocrine therapy (ET) is indicated in patients with steroid hormone receptor (HR)-positive breast cancer. The aim of this study was to evaluate the quality of HR determination and adjuvant endocrine treatment of breast cancer patients in a large cohort of more than 7000 women by analyzing data from a population-based regional cancer registry.

METHODS

Data from the Clinical Cancer Registry Regensburg (Bavaria, Germany) were analyzed. Female patients with primary, nonmetastatic invasive breast cancer who were diagnosed between 2000 and 2012 (n = 7421) were included. HR-status was available in 97.4 % (n = 7229) of the patients. This data set (n = 7229) was used for subsequent statistical analyses.

RESULTS

Since 2009, almost a complete rate of 99.6 % of analyzed HR-status was achieved. In sum, 85.8 % of the patients (n = 6199) were HR-positive, whereas 14.2 % (n = 1030) were HR-negative. Overall, 85.3 % (n = 5285) of HR-positive patients received ET either alone or in combination with chemotherapy (CHT) and/or trastuzumab. The majority of premenopausal patients received CHT plus ET (716 patients, 52.3 %). In postmenopausal patients, the most frequent systemic therapy was ET alone (2670 patients, 55.3 %). Best overall survival (OS) was found in HER2-/HR-positive patients receiving CHT plus ET plus trastuzumab (7-year OS rate of 97.2 % in premenopausal patients versus 86.9 % in postmenopausal patients). Premenopausal patients had a reduced benefit from additional CHT than postmenopausal patients. Premenopausal patients receiving only ET had a 7-year OS rate of 95.3 % compared to 92.7 % of patients receiving CHT plus ET. In contrast, postmenopausal patients treated with CHT plus ET had a 7-year OS rate of 84.0 % in comparison with those patients receiving only ET with a 7-year OS rate of 81.7 %.

CONCLUSIONS

Analysis of HR in patients with early breast cancer achieved a very high quality in recent years. The vast majority of HR-positive patients received ET, and this guideline-adherent use improved OS. Inverse effects of the CHT plus ET combination in premenopausal versus postmenopausal patients and a still existing minority of patients not receiving guideline-adherent treatment should be further investigated in future studies.