Dose-dense neoadjuvant chemotherapy in triple-negative breast cancer: Real-world data from a developing country.

Abstract

e12594 Background: Dose-dense adjuvant chemotherapy has been shown to be associated with improved long-term survival outcomes in triple-negative breast cancer (TNBC). However, there is a lacuna of data on the benefits of dose-dense neo-adjuvant chemotherapy (NACT) in TNBC particularly with respect to pathological complete response (pCR) rates and with the relapse or overall survival. To our knowledge no studies have been reported regarding the use or benefit of dose-dense NACT (ddNACT) over conventional NACT (cNACT) among Indian women with TNBC. Methods: This retrospective study included, 217 newly diagnosed cases of TNBC, treated with sequential anthracycline and taxane based NACT followed by definitive surgery. Study groups consisted of 137 patients who received 3-weekly conventional chemotherapy (cNACT group) and 80 patients with 2-weekly dose-dense NACT (ddNACT group) with granulocyte-colony-stimulating factor (GCSF) prophylaxis. Primary endpoint of the study was pathological complete response (pCR) rate and secondary endpoints were relapse-free survival (RFS), overall survival (OS) and grade-3/4 chemotoxicities. Fisher’s exact test was used to compare pCR rates. Kaplan-Meier and cox regression survival analysis were used to compare survival outcomes. Results: Median age (Interquartile range) in overall population, cNACT and ddNACT group were 43 (37-50), 44 (37-50) and 42 (36.5-48) years respectively. Baseline parameters were comparable between study groups, except that ddNACT group had higher proportion of premenopausal patients as compared to cNACT group (72.5% vs 55.5%). Majority of the patients presented at advanced stage, with stage-III being predominant, constituted by 97 (70.1%) and 55 (67.5%) patients in cNACT and ddNACT group respectively. No significant difference in pCR rate (32.8% vs 31.3%; p=0.808) was observed across the study groups. In multivariate analysis, dose-dense chemotherapy was no better than conventional chemotherapy for achieving pCR (Odds ratio [OR]: 0.86, 95% confidence interval [CI]: 0.45-1.63; p=0.639 and had no RFS advantage over conventional chemotherapy [Median RFS: Not reached in ddNACT vs 56.1 months in cNACT; Hazard Ratio: 0.83, 95% CI (0.48-1.44)]. OS was also comparable in both the groups with 3-year survival rate of 78.8% (95%CI: 60.9-89.2) in ddNACT group vs 84.3% (95% CI: 74.8-90.4) in cNACT group. Grade-3/4 toxicities were comparable in both groups. Conclusions: This observational study focusing on ddNACT among TNBC patients demonstrated similar pCR and toxicity rates with no significant survival benefits compared to cNACT regimen. Cost-benefits of frequent hospital visits for GCSF administration associated with dose dense therapy need further consideration before implementing such these regimens in lower-middle income countries.