ABSTRACT
Purpose@#Based on the results of previous trials, de-escalation of axillary surgery after neoadjuvant chemotherapy (NAC) has increased in patients with axillary lymph node (ALN) metastasis at presentation. This study aimed to review the trends of axillary surgery by time period and molecular subtype in patients with ALN metastasis. @*Methods@#We analyzed the rates of sentinel lymph node biopsy (SLNB) and ALN dissection (ALND) based on time period and subtype. The time period was divided into 3 subperiods to determine the rate of axillary surgery type over time (period 1, from 2009 to 2012; period 2, from 2013 to 2016; and period 3, from 2017 to July 2019). @*Results@#From 2009 to July 2019, 2,525 breast cancer patients underwent surgery. Based on subtype, the ALND rate of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2–) disease decreased by 13.0% from period 1 to period 3 (period 1, 99.4%; period 2, 97.5%; and period 3, 86.4%; P < 0.001). Conversely, the ALND rate in HR+/HER2+, HR–/HER2+, and triple-negative breast cancer (TNBC) significantly decreased by 43.7%, 48.8%, and 35.2% in period 1, period 2, and period 3, respectively (P < 0.001). In the patient group receiving NAC, HR+/HER2– had a significantly higher ALND rate (84.1%) than HR+/HER2+, HR–/HER2+, and TNBC (60.8%, 62.3%, and 70.7%, respectively; P < 0.001). @*Conclusion@#The SLNB rate in patients with ALN metastasis has increased over time. However, the ALND rate in HR+/ HER2– was significantly higher than in other subtypes.
ABSTRACT
Most textbooks for biostatistics only explain each individual statistical test with its mathematical formula. However, it is crucial to understand the relationships among the statistical methods and to properly integrate the individual methods to effectively apply them to real clinical research settings. The choice for valid statistical tests greatly depends on the dependency of the sample and the number of independent variables in the analyses as well as the measurement scale of dependent variables and independent variables. In this report, many statistical tests such as the two sample t-test, ANOVA, non-parametric tests, chi-square test, log-rank test, multiple linear regression, logistic regression, mixed model, and Cox regression model are addressed through hypothetical examples. The key for a successful analysis of a clinical experiment is to adopt suitable statistical tests. This study presents a guideline to clinical researchers for selecting valid and powerful statistical tests in their study design. The choice of suitable statistical tests increases the reliability of analytical results and therefore the possibility of accepting a researcher's clinical hypothesis. The proposed flowchart of appropriate tests of statistical inference will be of help to many clinical researchers to their study.