Aims: To identify triple-negative breast cancer (TNBC) patients who received neoadjuvant chemotherapy (NAC) and achieved pathological complete response (pCR) to examine associations with overall and breast cancer-specific survival (OS; BCSS).
Methods: TNBC patients were identified from Queensland Oncology Repository (female, 18+, 2017-2019); followed up to Dec 2021(BCSS) and Feb 2024(OS). Paget’s disease, stage IV, and patients without treatment were excluded. pCR was defined as no residual disease after NAC regardless of lymph node status. Multivariable models identified the likelihood of receiving NAC and achieving pCR. Survival rates were estimated for no NAC versus NAC with pCR, and NAC without pCR, using Kaplan-Meier, and adjusted hazard ratio (HR) were estimated using flexible parametric survival models at 1-, 2-, and 4-year survival.
Results: 1,021 TNBC patients were included; 21.5% received NAC, with NAC common in those living in major cities (24.4%) and outer-regional/rural areas (21.9%) compared to those in inner-regional areas (12.6%). Patients who received NAC (versus not) were younger (49.0±13.0y vs. 61.4±14.6y) and more commonly diagnosed with stage IIIa-IIIc (70.5% vs 53.1%). Among those who had NAC, 42.4% achieved pCR. pCR was more common in those with stage IIa-IIb (62.5%) versus stage IIIa-IIIc (34.9%). Compared to those who did not receive NAC, those who did and achieved pCR had better OS (HR 0.27-0.41; p>0.05) at 1-, 2- and 4-years post-diagnosis, whereas those who did not achieve pCR had significantly poorer OS (HR 2.22-3.57; p<0.05) at all follow-up years. Trends were similar for BCSS.
Conclusions: Patients who received NAC and achieved pCR had better survival. Receipt of NAC however, differed by age and geographical region, with those living in inner-regional areas less likely to receive NAC. Equitable access to optimal care is essential for addressing survival disparities. Continued research for TNBC is vital for those who do not benefit from current treatments.