Adjuvant chemotherapy and survival in women aged 70 years and older with triple-negative breast cancer: a Swedish population-based propensity score-matched analysis

Abstract

Background Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer associated with poor survival, in which adjuvant systemic treatments are limited to chemotherapy. Due to competing mortality risks and comorbidities, older patients with TNBC are often undertreated with adjuvant chemotherapy, and clinical trials on this problem are scarce, despite a growing patient population. This study aimed to assess outcomes for patients aged 70 years and older with TNBC with or without chemotherapy in a national population-based registry, to provide information that can assist in treatment decisions for these patients.Methods In this population-based registry study, data on all patients aged 70 years and older diagnosed with primary early TNBC (larger than 5 mm in diameter and without distant metastasis) and surgically treated between Jan 1, 2009, and Dec 31, 2016, were retrieved from the Swedish National Breast Cancer Register, the Swedish Patient Register, and the Swedish Cause of Death Register. Patients with incomplete data (on oestrogen receptor, progesterone receptor, or human epidermal growth factor receptor 2 status, surgical procedure in the breast, or information about chemotherapy) were excluded. A propensity score-matched (PSM) model was used to examine the outcomes of adjuvant chemotherapy on 5-year breast cancer-specific survival (BCSS) and 5-year overall survival (OS), adjusted for age, tumour size, tumour grade, nodal status, and comorbidities. FindingsOf 1130 women eligible for analysis, 368 (32•6%) received adjuvant chemotherapy, 45 (4•0%) received neoadjuvant treatment, and 717 (63•5%) did not receive chemotherapy. 5-year BCSS was significantly improved in patients who received adjuvant chemotherapy (85% [95% CI 81-89]) compared with patients who did not receive chemotherapy (68% [64-72]; p<0•0001). A similar benefit was observed in 5-year OS (79% [95% CI 75-84] vs 49% [45-53]; p<0•0001). In our PSM analysis, 5-year BCSS in patients treated with adjuvant chemotherapy was 83% (95% CI 78-89), versus 73% (67-80; p=0•014) in patients not treated with chemotherapy. 5-year OS in patients treated with adjuvant chemotherapy was 75% (95% CI 69-82), versus 63% (57-71; p=0•029) in patients who did not receive chemotherapy.Interpretation In this PSM registry analysis of surgically treated female patients aged 70 years and older with TNBC without distant metastasis, we identified a significant benefit both in 5-year BCSS and 5-year OS with adjuvant chemotherapy versus no chemotherapy, which persisted when adjusting for age and comorbidities. These results underline the importance of considering adjuvant chemotherapy in older patients.

Risk Stratification Model for Predicting the Overall Survival of Elderly Triple-Negative Breast Cancer Patients: A Population-Based Study

“…In particular, a study by Slavica used the large cancer database of Sweden for their analysis and found that the 5-year OS of patients with adjuvant chemotherapy was 12% higher than that of patients who did not participate in chemotherapy through the propensity matching score method. Using the US National Cancer Database, another study by Jennifer also found that the 5-year OS of patients with adjuvant chemotherapy were 15% higher than that of patients who did not participate in chemotherapy ( 28 , 29 ). Recently, the object of several controversial reports focused on the value of adjuvant radiotherapy for TNBC.…”

“…The Kaplan-Meier curve in the low-risk group showed that the risk stratification system could accurately distinguish the OS of the total cohort, training cohort, and validation cohort. In all cohorts, the median OS was 56 (95% CI 52-63), while it was and 24 (95% CI [22][23][24][25][26][27][28] in the moderate-risk and high-risk groups, respectively, and no median survival was observed in the low-risk group.…”

Chemotherapy Decision-Making and Survival Outcomes in Older Women With Early Triple-Negative Breast Cancer: Evidence From Real-World Practice

“…Although nearly 80% of patients in our cohort had comorbidities, few had diseases that severely impacted their functional status, as only 4 patients scored CCI ≥3, which may partly explain the lack of correlation between comorbidities and treatment decisions or survival outcomes. The sample size of our study was smaller than that of other population-based studies ( 14 , 15 ), which may have limited our ability to analyze survival in relation to CCI values. The findings indicate that individualized assessment using developed tools such as the CCI are beneficial for estimating life expectancy and functional status among older patients with multiple comorbidities.…”

“…In the current study, comorbidity and the Charlson Comorbidity Index (CCI) failed to affect chemotherapy decisions and survival outcomes. A previous study revealed that chemotherapy is rarely recommended for older breast cancer patients with a CCI value ≥3 ( 3 ), and that patients with a higher CCI value had significantly worse OS outcomes ( 14 , 15 ). Based on the comorbid conditions listed in the CCI, we considered numerous highly prevalent comorbidities, such as hypertension ( 19 , 20 ).…”

“…Some studies suggested that advanced age is associated with an indolent disease course and a diminished need for aggressive therapy ( 10 , 11 ), while others indicated that inadequate treatment contributes to a survival disadvantage ( 12 , 13 ). Fortunately, two population-based studies ( 14 , 15 ) have recently been published that analysed data from the National Cancer Database (NCDB) in the USA and the Swedish National Breast Cancer Register (NBCR) and suggested that chemotherapy yielded survival benefits in older women with early TNBC. However, the two national databases did not specify the chemotherapy regimens, dosage, number of cycles, or tolerance levels.…”