Currently about one-quarter of breast cancers (BCs) are diagnosed in women aged 70 to 84 years, but this is expected to increase to over one-third within the next decade. Although older women typically have hormonally responsive disease, about 12% to 17% of BCs in the United States are triple-negative BC, which is more difficult to treat. There are limited data about the management of triple-negative BC in older woman with therapeutic regimens extrapolated from younger populations.
Using data from the National Cancer Database (NCDB), a nationwide, facility-based database that includes information on approximately two-thirds of all newly diagnosed BC that occur annually in the U.S, researchers examined the recommendations for treatment as well as the actual use of chemotherapy in women aged 70 years or older with triple-negative BC. The NCDB houses data on patients who have received therapy, those for whom chemotherapy was not recommended, and those for whom drug treatment was advised but was not administered.
The NCDB was searched for all women who had invasive infiltrating ductal carcinoma or invasive lobular carcinoma of the breast between 2004 and 2014. A propensity-matched analysis was then performed on women aged 70 years or older with nonmetastatic, invasive ductal, or lobular breast carcinoma (AJCC Stage I-III) who were triple-negative (i.e., estrogen-receptor negative, progesterone-receptor negative, and HER2-negative) and who had undergone any type of BC surgical intervention. Additional inclusion criteria were primary tumor 6 mm or greater or at least one positive lymph node.
BC patients could have received either neoaduvant or adjuvant treatment; most women who received treatment were administered the latter form of therapy. The Charleson-Deyo comorbidity score was used as a surrogate for performance status. Tumor size was utilized in lieu of T-staging.
Patients were divided into three subgroups: those who were recommended to receive chemotherapy but did not receive it either due to patient preference or undocumented reasons; those who received chemotherapy either preoperatively or postoperatively; and those for whom chemotherapy was neither recommended nor administered.
The primary outcome of this study was overall survival. Kaplan-Meier survival curves and overall survival were assessed. Propensity matching was performed based on age, comorbidity score, tumor grade, tumor size, nodal status, and radiotherapy use. The effect of chemotherapy by nodal status and comorbidity score were determined. The effect of chemotherapy as a function of age was examined.
Between January 1, 2004 to December 31, 2014, 1,477,365 patients in the U.S. were diagnosed with either invasive ductal or lobular carcinoma and of these, 411,372 (27.8%) were aged 70 years or older. Of these 411,372 patients, 16,062 (3.9%) met the inclusion criteria and were enrolled in the study. Investigators found that fewer than half (46.6%) of older patients received chemotherapy. Among these patients, 5,924 (79.1%) received adjuvant chemotherapy, 1,337 (17.9%) received neoadjuvant therapy, and 196 (2.6%) received both. Of the remaining patients, chemotherapy was not recommended in over one-third (35.7%) and chemotherapy was advised but not administered in about 17% of patients.
Patients were followed for a median of 38.3 months (range: 0-138 months). At data cutoff on January 31, 2016, approximately 21% of patients had expired. The overall 5-year survival rate was 62.3%. Taking a closer look, the overall 5-year survival was 68.5% among those who had received chemotherapy, 61.1% for those for whom chemotherapy was recommended but not given, and only 53.7% for those whom therapy was not advised. Patients who were recommended chemotherapy but did not receive it fared better than those for whom the recommendation was to withhold treatment. A similar trend was seen for those who received radiotherapy.
Patients who received chemotherapy were propensity-score matched against those for whom chemotherapy was recommended but not received. Median tumor sizes were 24 mm and 18 mm, respectively, after matching. Overall 5-year survival was 31% higher in those who had received chemotherapy compared with those for whom it was recommended but not administered. A similar trend in 5-year overall survival was seen in node-positive women and node-negative women, with the former group having increased survival.
One limitation of using the NCDB data is that it does not specify which chemotherapeutic agent was administered nor does it provide information on the dose, the number of cycles, the duration of treatment, the presence of any toxicities, or the cause of death. The researchers concluded that in older women with triple-negative BC, there is a significant overall survival benefit associated with systemic chemotherapy.
This study provides encouraging information for pharmacists who counsel older adults on the risk versus benefit of chemotherapy.
The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.
« Click here to return to Breast Cancer Update.