The Potential Use of Tumour-Based Prognostic and Predictive Tools in Older Women with Primary Breast Cancer: A Narrative Review

Overexpression of Estrogen Receptor α in Mammary Glands of Aging Mice Is Associated with a Proliferative Risk Signature and Generation of Estrogen Receptor α-Positive Mammary Adenocarcinomas

Age is a risk factor for human estrogen receptor-positive breast cancer, with highest prevalence following menopause. While transcriptome risk profiling is available for human breast cancers, it is not yet developed for prognostication for primary or secondary breast cancer development utilizing at-risk breast tissue. Both estrogen receptor α (ER) and aromatase overexpression have been linked to human breast cancer. Herein, conditional genetically engineered mouse models of estrogen receptor 1 (Esr1) and cytochrome P450 family 19 subfamily A member 1 (CYP19A1) were used to show that induction of Esr1 overexpression just before or with reproductive senescence and maintained through age 30 months resulted in significantly higher prevalence of estrogen receptor-positive adenocarcinomas than CYP19A1 overexpression. All adenocarcinomas tested showed high percentages of ER+ cells. Mammary cancer development was preceded by a persistent proliferative transcriptome risk signature initiated within 1 week of transgene induction that showed parallels to the Prosigna/Prediction Analysis of Microarray 50 human prognostic signature for early-stage human ER+ breast cancer. CYP19A1 mice also developed ER+ mammary cancers, but histology was more divided between adenocarcinoma and adenosquamous, with one ER- adenocarcinoma. Results demonstrate that, like humans, generation of ER+ adenocarcinoma in mice was facilitated by aging mice past the age of reproductive senescence. Esr1 overexpression was associated with a proliferative estrogen pathway-linked signature that preceded appearance of ER+ mammary adenocarcinomas.

Validation of the 70-gene signature test (MammaPrint) to identify patients with breast cancer aged ≥ 70 years with ultralow risk of distant recurrence: A population-based cohort study

INTRODUCTION

When risk estimation in older patients with hormone receptor positive breast cancer (HR + BC) is based on the same factors as in younger patients, age-related factors regarding recurrence risk and other-cause mortality are not considered. Genomic risk assessment could help identify patients with ultralow risk BC who can forgo adjuvant treatment. However, assessment tools should be validated specifically for older patients. This study aims to determine whether the 70-gene signature test (MammaPrint) can identify patients with HR + BC aged ≥70 years with ultralow risk for distant recurrence.

MATERIALS AND METHODS

Inclusion criteria: ≥70 years; invasive HR + BC; T1-2N0-3M0.

EXCLUSION CRITERIA

HER2 + BC; neoadjuvant therapy. MammaPrint assays were performed following standardized protocols. Clinical risk was determined with St. Gallen risk classification. Primary endpoint was 10-year cumulative incidence rate of distant recurrence in relation to genomic risk. Subdistribution hazard ratios (sHR) were estimated from Fine and Gray analyses. Multivariate analyses were adjusted for adjuvant endocrine therapy and clinical risk.

RESULTS

This study included 418 patients, median age 78 years (interquartile range [IQR] 73-83). Sixty percent of patients were treated with endocrine therapy. MammaPrint classified 50 patients as MammaPrint-ultralow, 224 patients as MammaPrint-low, and 144 patients as MammaPrint-high risk. Regarding clinical risk, 50 patients were classified low, 237 intermediate, and 131 high. Discordance was observed between clinical and genomic risk in 14 MammaPrint-ultralow risk patients who were high clinical risk, and 84 patients who were MammaPrint-high risk, but low or intermediate clinical risk. Median follow-up was 9.2 years (IQR 7.9-10.5). The 10-year distant recurrence rate was 17% (95% confidence interval [CI] 11-23) in MammaPrint-high risk patients, 8% (4-12) in MammaPrint-low (HR 0.46; 95%CI 0.25-0.84), and 2% (0-6) in MammaPrint-ultralow risk patients (HR 0.11; 95%CI 0.02-0.81). After adjustment for clinical risk and endocrine therapy, MammaPrint-high risk patients still had significantly higher 10-year distant recurrence rate than MammaPrint-low (sHR 0.49; 95%CI 0.26-0.90) and MammaPrint-ultralow patients (sHR 0.12; 95%CI 0.02-0.85). Of the 14 MammaPrint-ultralow, high clinical risk patients none developed a distant recurrence.

DISCUSSION

These data add to the evidence validating MammaPrint's ultralow risk threshold. Even in high clinical risk patients, MammaPrint-ultralow risk patients remained recurrence-free ten years after diagnosis. These findings justify future studies into using MammaPrint to individualize adjuvant treatment in older patients.

Biology of primary breast cancer in older women beyond routine biomarkers

Purpose

There are numerous biomarkers which may have potential predictive and prognostic significance in breast cancer. This is extremely important in older adults, who may opt for less aggressive therapy. This work outlines the literature on biological assessment outside of standard biomarkers (defined as ER, PgR, HER2, Ki67) in women ≥ 65 years with primary operable invasive breast cancer, to determine which additional biomarkers are relevant to outcome in older women.

Methods

Medline and Embase databases were searched. Studies were eligible if included ≥ 50 patients aged ≥ 65 years; stratified results by age; measured a biomarker outside of standard assay and reported patient data.

Results

A total of 12 studies were appraised involving 5000 patients, measuring 28 biomarkers. The studies were extremely varied in methodology and outcome but three themes emerged: 1. Differences in biomarker expression between younger and older women, indicating that breast cancer in older women is generally less aggressive compared to younger women; 2. Relationship of biomarker expression with survival, suggesting biomarkers which may exclusively predict response to primary treatment in older women; 3. Association of biomarker with chemotherapy, suggesting that older patients should not be declined chemotherapy based on age alone.

Conclusion

There is evidence to support further investigation of B-cell lymphoma (BCL2), liver kinase (LK)B1, epidermal growth factor receptor (EGFR), cytoplasmic cyclin-E, mucin (MUC)1 and cytokeratins (CKs) as potential predictive or prognostic markers in older women with breast cancer undergoing surgery. Studies exploring these biomarkers in larger cohorts and in women undergoing non-operative therapies are required.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12282-021-01266-5.