Efficacy of extended aromatase inhibitors for hormone-receptor-positive breast cancer: A literature-based meta-analysis of randomized trials

BACKGROUND

Endocrine treatment with Tamoxifen and aromatase inhibitors (AIs) is a staple in the management of hormone receptor positive breast cancer (HR + BC). It has become clear that HR + BC carries a consistent risk of relapse up to 15 years post-diagnosis. While increasing evidence supports the use of extended adjuvant Tamoxifen over 5 years, controversial data are available on the optimal duration of extended AIs adjuvant treatment. We performed a meta-analysis to assess the real impact of extended adjuvant therapy with AIs on disease-free survival (DFS).

METHODS

A literature-based meta-analysis of randomized controlled trials (RCTs) was undertaken. Relevant publications from PubMed, the Cochrane Library, and abstracts from American Society of Clinical Oncology (ASCO) and San Antonio Breast Cancer (SABCS) symposia were searched. Primary and secondary endpoints were Disease Free Survival (DFS) and overall survival (OS) respectively. A subgroup analysis was also performed to elucidate the impact of nodal involvement.

RESULTS

The pooled analysis revealed a significant increase in DFS in the extended AIs group (hazard ratio (HR): 0.78, 95% CI: 0.68-0.90; P = 0.0006). The subgroup analysis according to nodal status showed a greater DFS benefit with extended AIs in patients with positive nodes (HR = 0.67 versus 0.80). Our analysis also demonstrated no improvement in OS with extended AIs (HR = 0.99, 95%CI: 0.87-1.12; P = 0.84).

CONCLUSION

This work confirmed the efficacy of extended adjuvant treatment with AIs for HR + early breast cancer, with a 22% increase in DFS, but no impact on OS. Greater efficacy was observed in women with positive nodal status.

A unifying biology of sex steroid-induced apoptosis in prostate and breast cancers

Prostate and breast cancer are the two cancers with the highest incidence in men and women, respectively. Here, we focus on the known biology of acquired resistance to antihormone therapy of prostate and breast cancer and compare laboratory and clinical similarities in the evolution of the disease. Laboratory studies and clinical observations in prostate and breast cancer demonstrate that cell selection pathways occur during acquired resistance to antihormonal therapy. Following sex steroid deprivation, both prostate and breast cancer models show an initial increased acquired sensitivity to the growth potential of sex steroids. Subsequently, prostate and breast cancer cells either become dependent upon the antihormone treatment or grow spontaneously in the absence of hormones. Paradoxically, the physiologic sex steroids now kill a proportion of selected, but vulnerable, resistant tumor cells. The sex steroid receptor complex triggers apoptosis. We draw parallels between acquired resistance in prostate and breast cancer to sex steroid deprivation. Clinical observations and patient trials confirm the veracity of the laboratory studies. We consider therapeutic strategies to increase response rates in clinical trials of metastatic disease that can subsequently be applied as a preemptive salvage adjuvant therapy. The goal of future advances is to enhance response rates and deploy a safe strategy earlier in the treatment plan to save lives. The introduction of a simple evidence-based enhanced adjuvant therapy as a global healthcare strategy has the potential to control recurrence, reduce hospitalization, reduce healthcare costs and maintain a healthier population that contributes to society.

Forty years of landmark trials undertaken by the Danish Breast Cancer Cooperative Group (DBCG) nationwide or in international collaboration

BACKGROUND

Over the past 40 years the Danish Breast Cancer Cooperative Group (DBCG) has made significant contributions to improve outcome and to make treatment of patients with early breast cancer more tolerable through nationwide and international trials evaluating loco-regional and systemic treatments. These trials have been instrumental to establish standards for the treatment of early breast cancer.

METHODS

The DBCG 82 trials had a global impact by documenting that the significant gain in loco-regional recurrence from postmastectomy radiation added to systemic therapy was associated with a reduction in distant recurrence and mortality in high-risk pre- and postmenopausal patients. The DBCG trials comparing breast conserving surgery and radiotherapy with mastectomy and more recently the trial of internal mammary node irradiation also had a major impact of practice. The trials initiated by the DBCG 40 years ago on tamoxifen and cyclophosphamide based chemotherapy became instrumental for the development of adjuvant systemic therapy not only due to their positive results but by sharing these important data with other members of the Early Breast Cancer Trialist' Collaborative Group (EBCTCG). Trials from the DBCG have also been important for highlighting the relative importance of anthracyclines and taxanes in the adjuvant setting. Furthermore, DBCG has made a major contribution to the development of aromatase inhibitors and targeted adjuvant treatment for human epidermal growth factor receptor 2 positive breast cancers.

RESULTS

The substantial impact of these treatment improvements is illustrated by a 46.7% 10-year overall survival of early breast cancer patients treated in 1978-1987 compared to 71.5% for patients treated 2008-2012.

CONCLUSIONS

The trials conducted and implemented by the DBCG appear to have a major impact on the substantial survival improvements in breast cancer.

ASCO 2017: highlights in breast cancer

At the 2017 ASCO Annual Meeting, several pertinent studies in the field of breast cancer were presented and some are deemed as being potentially practice changing. BrighTNess was the first phase III study to investigate the addition of carboplatin to standard neoadjuvant chemotherapy in triple-negative breast cancer; while toxicity was increased in the experimental group, a significantly higher pathologic complete remission (pCR) rate was observed as well suggesting that adding carboplatin to neoadjuvant anthracycline, cyclophosphamide and taxane-containing regimens is efficacious in otherwise healthy patients. In metastatic breast cancer patients harbouring BRCA germ-line mutations, the PARP(poly [ADP-ribose] polymerase)-inhibitor olaparib was superior to conventional chemotherapy defining a potential novel treatment standard in this high-risk population. In the adjuvant setting, the APHINITY trial compared dual HER2-directed antibody therapy with trastuzumab plus pertuzumab to trastuzumab alone. A small benefit in favour of the combination was observed which was more pronounced in node-positive subjects. In hormone-receptor positive metastatic disease, several studies evaluating the role of CDK4/6 (cyclin-dependendent kinases 4 and 6) inhibitors were presented with data again indicating that adding CDK4/6 inhibitors to endocrine therapy results in a clinically relevant prolongation of progression-free survival.

Optimal duration of adjuvant endocrine therapy: how to apply the newest data

Background:

The benefit of 5 years of adjuvant endocrine therapy for women with hormone receptor-positive (HR⁺) breast cancer (BC) is beyond discussion. Nevertheless, the risk of recurrence of luminal BC persists for 15 years or more after diagnosis. Consequently, approaches of extended adjuvant therapy have been investigated in large clinical trials, with the ultimate aim of further reducing the risk of recurrence in patients with HR⁺ BC.

Methods:

A review of recently published trial data is presented to provide a solid basis for discussion. A discussion of the side effects of long-term endocrine treatment, multigenetic tests aiming to identify patients at particular risk, and an outlook for further promising targets are additional aims of this review.

Conclusion:

Extended adjuvant therapy seems beneficial in reducing distant relapse and contralateral BC for a selected group of patients with HR⁺ BC, particularly if aromatase inhibitors (AIs) are used after initial tamoxifen therapy. However, patients with lower risk of recurrence and initial AI therapy may suffer more from side effects than benefit from extended therapy.