Abstract Introduction Docetaxel and cyclophosphamide (TC) is a widely used anthracycline-free regimen for hormone receptor-positive (HR+) early-stage breast cancer. While typically administered over four to six cycles, the optimal number of cycles for various risk profiles remains a topic of clinical debate. This study aimed to identify clinical and pathological factors associated with the number of adjuvant TC cycles prescribed in a real-world setting. Methods We conducted a retrospective analysis of patients with HR+ early-stage breast cancer treated between 2018 and 2025 across a multicenter oncology network in Brazil. Eligible patients had undergone surgery and received adjuvant TC chemotherapy. Variables such as age, menopausal status, tumor size and nodal status, histologic grade, and Ki-67 index were examined in relation to the number of TC cycles administered (six versus four). For patients who received four cycles, we recorded whether this was based on the original treatment plan, early discontinuation due to adverse events, or other reasons. Logistic regression was used to evaluate associations between baseline characteristics and the likelihood of receiving fewer versus more TC cycles. Results A total of 372 patients who received adjuvant TC were evaluated; 206 (55.4%) received four cycles and 166 (44.6%) received six cycles. Among those receiving four cycles, the majority (87.9%) had this number planned at the outset. Only four patients (1.9%) had the number of cycles reduced due to treatment-related toxicities. The reason for choosing four cycles was not documented in the remaining 10.2%. Patients who received six cycles were slightly younger (median age 50 years range 27-81) than those receiving four cycles (median age 52 years range 29-83; P=0.025). The six-cycle group had a higher proportion of patients with positive lymph nodes (42.2% pN1 and 3.6% pN2) compared to the four-cycle group (19.9% pN1 and 0.9% pN2; P0.001), and a greater proportion of grade 3 tumors (34.3% vs. 28.6%; P=0.048). No significant differences were observed in primary tumor size, menopausal status, or Ki-67 index. In multivariable logistic regression, lymph node status, tumor grade, and age were significantly associated with receiving six TC cycles (Table). Increasing age was associated with a lower likelihood of receiving six cycles, while pN1, pN2, and grade 3 tumors were associated with higher odds. Conclusion These findings suggest that treatment duration with TC is influenced not only by formal staging criteria but also by individualized clinical judgment reflecting perceived recurrence risk and patient tolerance. Further studies are needed to determine whether six versus four cycles of TC differ in efficacy when compared in cohorts balanced for these baseline factors. Citation Format: W. A. Lima, R. Naves, R. C. Bonadio, B. Pego, L. Amorim, G. J. Filheiro, C. Cavalcanti, L. Holland, J. Bessa, P. H. Divino, M. Nishimuni, L. G. Torres, J. Bines, L. Testa. Factors influencing the number of adjuvant TC - docetaxel and cyclophosphamide - cycles in hormone receptor-positive early-stage breast cancer abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-10-02.
Lima et al. (2026) studied this question.