Radiation therapy of the primary tumour and oligometastatic sites in patients with breast cancer with synchronous metastases: A literature review

De novo metastatic breast cancer represents 5 to 8% of all breast cancers (2500 new cases per year in France). Systemic treatment is the cornerstone of treatment, whereas radiation therapy usually has a palliative intent. Advances in systemic and local treatments (surgery and radiation therapy) have substantially improved overall survival. In the recent breast cancer statistics in the United States, the 5-year relative survival for patients diagnosed during 2012-2018 was 29% for stage IV (Breast Cancer Statistics). Thus, an increasing proportion of metastatic breast cancers present a prolonged complete response to systemic therapy, which raises the question of the impact of local treatment on patient survival. Radiation therapy has shown its value for early breast cancer, but its place in the local management of the primary tumour or oligometastatic sites for de novo metastatic breast cancer remains under debate. This article is a literature review assessing the role of radiation therapy directed to the primary tumour and oligometastatic sites of breast cancer in patients with synchronous metastases, in order to highlight clinicians in their therapeutic decision.

[Real-world study of the consumption between 2017 and 2020 of anti-cancer medications that inhibit cyclin- dependent kinases 4 and 6]

The real-world study of data from the Système National des Données de Santé (French System of Health Data) in relation to therapeutic indications that give entitlement to having Assurance Maladie (Health-Insurance Fund) pay for, or reimburse the cost of, inhibitors of cyclin-dependent kinases 4 and 6 (iCDK4/6) shows that the target population defined by the Haute Autorité de santé (HAS-National Health Authority) has been significantly exceeded ; in addition, there is a gap with respect to reimbursable indications and therapeutic strategy. The HAS has set the upper limit of the eligible population at 5 320 new patients per year, but in 2019, Assurance Maladie reimbursed iCDK4/6-related costs for 10 894 patients, i.e. double the number. Therapeutic strategies are found that do not comply with the opinions of the commission de la transparence (transparency commission) in 30 % of cases, and that do not comply with reimbursable therapeutic indications in 22 % of cases. Patient profiles are not in line with reimbursable indications in terms of age (women aged under 50 and, a priori, non-menopausal) and sex (men) in 14 % of cases. Furthermore, treatment seems to be started at an advanced stage of the disease, based on the number of deaths observed after treatment is started: 13% of patients died in the year following the start of treatment, including 26 % in the first three months. There is a significant volume of treatment being started, but there is also a significant volume of stoppage. One third of patients for whom treatment was started in 2019 had their treatment stopped after less than one year, including half after less than three months.

[Updates in hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer in 2021]

Overall, 2021 was marked by the confirmation of the major interest of cell cycle inhibitors for hormone receptor (HR) positive/human epidermal growth factor receptor 2 (HER2) negative advanced breast cancers with very high overall survival data exceeding five years for hormone-sensitive disease. Studies have also confirmed the efficacy and safety of this therapeutic class in the elderly population. New cell cycle inhibitors are under development (SHR6390). New combinations are also being evaluated, notably palbociclib with SAR439859 (a new selective estrogen receptor degrader: SERD). Targeting of the Phosphoinositide 3-kinases (PI3K) pathway by taselisib, in hormone-resistant disease with a Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha (PIK3CA) mutation, modestly improves progression-free survival but with a non-negligible toxicity of the treatment.

[Patients treated with palbociclib and endocrine therapy for metastatic breast cancer: Can we predict the occurrence of severe early hematological toxicity?]

INTRODUCTION

The addition of palbociclib to endocrine therapy has been shown to improve progression free survival in hormone receptor positive metastatic breast cancer patients. This cyclin CDK4/6 inhibitor could expose patients to a grade 3-4 hematological toxicity, leading to treatment discontinuation or treatment interruption that is potentially associated with a lack of efficiency. The aim of this study was to identify predictive factors of severe early hematotoxicity (ESHT).

METHODS

This retrospective cohort study included patients who started palbociclib in the Institut Sainte Catherine between December 1, 2016 and January 1, 2019 for the treatment of metastatic breast cancer. Individual data and hematological toxicity were collected from electronic medical records. ESHT was defined as the occurrence, during the first 3 cycles, of grade 4 or grade 3 hematological toxicity requiring palbociclib dose reduction.

RESULTS

In total, 181 patients (180 females) were included; median age was 67 years. Forty-six patients (25.4%) experienced an ESHT. Predictive factors of ESHT in multivariate analysis were a performance status (PS) of 2 or more (P=0.024) and an history of radiotherapy of bone metastasis in the previous year (P=0.003). Before palbociclib initiation, a neutrophil count below 3.37g/L was predictive of ESHT with a sensibility of 76% and a specificity of 71%.

CONCLUSIONS

ECOG PS, bone radiotherapy within the year and low baseline neutrophils count are associated with ESHT in palbociclib-treated metastatic breast cancer patients. These elements could be useful for a careful monitoring leading to adapted therapy.

[Clinical relevance of ESR1 circulating mutations detection in hormone receptor positive metastatic breast cancer]

If hormone therapy is a key treatment for hormone receptor positive advanced breast cancers, secondary resistance occurs as a rule. Recently, acquired alterations of the ESR1 gene have been identified as a mechanism of resistance on aromatase inhibitor (AI) treatment. The selective pressure by AI exposure during the metastatic setting triggers the emergence of ESR1 activating mutations. In that context, the "liquid biopsy" concept has been used to detect this molecular resistance before progression. Thus, the ESR1 circulating mutation detection will soon be used in daily practice to help monitoring patients on AI treatment and provide an early change for specific therapies that still have to be determined in prospective clinical trials. This review will present the acquired ESR1 mutations, as well as the methods used for their detection in blood and the potential clinical impact of this approach for hormone receptor positive breast cancer management.