Background: ABC trials established the use of non-anthracycline containing regimen, docetaxel and cyclophosphamide (TC) in the adjuvant setting in early stage breast cancer. In clinical practice, TC is commonly used in Stage I Triple-Negative Breast Cancer (TNBC). However, no specific recommendations exist in literature, regarding the number of cycles that can be used. i.e. TC4 vs TC6. Our aim, was to determine if TC4 is non-inferior to TC6 when used as adjuvant therapy in early stage TNBC.

Methods: We retrospectively reviewed 77 patients who were diagnosed with early stage TNBC between 2007 to 2017, at our institution who had received either TC4 or TC6 as adjuvant therapy. The number of cycles the patients received were based on provider preference. The two groups (TC4, TC6) were compared in regard to stage of cancer at diagnosis based on AJCC 7thedition, grade of adverse events, recurrence and death from breast cancer recurrence.

Results: Out of 77 patients, based on T stage, 25 (32.5%) were T1b, 38(49.4%) were T1c, 13(16.9%) were T2 and 1(1.3%) was T3. All patients were node negative. 53(68.8%) received TC4 and 24(31.2%) received TC6. Regarding side effects, adverse of any grade were seen in 42(79.2%) patients who received TC4 and 23(95.8%) in patients who received TC6(p=0.091). Adverse events which were grade 3 or higher were seen in 7(15.9%) in TC4 group and 3(13%) in the TC6 group (p=1.000). Recurrence in the TC4 group was seen in 4 patients (7.5%) and 3(12.5%) patient in the TC6 group (p=0.259). Death due to breast cancer recurrence was seen in 1 patient (1.9%) in the TC4 group and 1(4.1%) patient in the TC6 group.

Conclusions: In this limited series, TC4 appears to be equally effective to TC6, with fewer adverse events of any grade. However, a longer follow up and a larger patient base is required to be studied for a more definitive conclusion.

Citation Format: Aparna Basu, Hadi A. Mohammed, Sharmeen Mahmood, Vrushali Dabak, Randa Loutfi. Four vs six cycles of docetaxel and cyclophosphamide (TC) in early stage triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3353.