ABSTRACT
Purpose@#Although the overall survival (OS) of breast cancer patients is increasing with improved detection and therapies, so is the risk of breast cancer patients developing subsequent malignancies. We investigated the OS of breast cancer survivors according to sites of second primary malignancies (SPM). The OS of the second primary hematologic malignancy (SPHM) was then compared with that of metastatic breast cancer (MBC). @*Methods@#We retrospectively analyzed patients diagnosed with primary breast cancer between 1998 and 2019. Only those with SPM were eligible for analysis. First, the OS of patients with SPM diagnosed as the first event after the diagnosis of breast cancer was analyzed. Next, the OS of patients with SPHM, with or without breast cancer relapse, was compared with that of patients with MBC, matched using the propensity score. @*Results@#Patients diagnosed with SPM without breast cancer relapse as the first event had a significantly better OS than did patients with MBC, but the OS of those with SPHM as the first event did not differ significantly from that of patients with MBC (hazard ratio [HR], 1.558; 95% confidence interval [CI], 0.856–2.839; P = 0.147). The OS of patients with SPHM with or without breast cancer relapse was worse than that of the MBC group after propensity score matching (HR, 1.954; 95% CI, 1.045–3.654; P = 0.036). @*Conclusion@#Prognosis of SPM diagnosed as the first event was statistically better than that of MBC, except in case of SPHM. Patients with SPHM, with or without MBC, showed poor OS before and after propensity score matching.
ABSTRACT
Purpose@#Whether administering chemotherapy followed by tamoxifen plus a gonadotropin-releasing hormone (GnRH) agonist to treat patients with lower-risk hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer provides a greater benefit than administering tamoxifen plus GnRH agonist alone remains unclear. This study aimed to compare the outcomes of propensity score-matched (PSM) patients who underwent these 2 types of treatment plans. @*Methods@#This retrospective study included patients treated at our institution between 2009 and 2019. Eligible patients had HR-positive, HER2-negative, invasive breast cancer who had undergone surgery. There were 579 patients with HR-positive, HER2-negative breast cancer who were treated with a GnRH agonist and tamoxifen; patients with pathologic N2 and those who received neoadjuvant chemotherapy were excluded. After 1:1 PSM of patients who underwent GnRH agonist treatment and tamoxifen with versus without chemotherapy, 122 patients from these 2 groups were analyzed. Survival rates were calculated using the Kaplan-Meier method and compared via the log-rank test. @*Results@#After PSM, there were no significant differences in several baseline characteristics between the 2 groups. After a median follow-up of 62.8 months, the patients in both groups demonstrated similar outcomes with no significant difference in disease-free survival (P = 0.596). @*Conclusion@#Patients derived no significant survival benefit from undergoing a chemotherapy regimen before receiving tamoxifen and GnRH agonist therapy compared to forgoing such chemotherapy.