There is a paucity of studies on platinum-based chemotherapy in advanced breast cancer (ABC) from developing countries like India.
This was a retrospective study of patients with ABC who were treated with platinum-based chemotherapy (gemcitabine carboplatin, GC) in a tertiary cancer center in India from Aug 2015 to Nov 2019. Patients were treated with injection gemcitabine 1gm/m2 on D1/D8 and injection carboplatin (AUC 5-6) on D1 for 6 cycles. Patients were assessed clinically before each cycle and by imaging before 4th and after the 6th cycle. Descriptive statistics were used to analyze the baseline characteristics. Survival was estimated with Kaplan Meier’s curve & univariate/multivariate analysis was done using regression analysis.
Baseline characteristics are listed in the table. 34 % & 91 % had metastatic disease at initial presentation and at the start of GC respectively. Repeat biopsy at metastatic disease was done in 37 % & 50 % had the same molecular subtype. Median number of prior lines of systemic therapy for metastatic/progressive disease was 1 (range: 0 to 5). The median number of sites of metastasis was 2 (range: 0 to 6). Patients with visceral crises were 23%. The median number of cycles of GC chemotherapy received was 6 (range: 2 to 6). A dose reduction of chemotherapy was done in 74%.Only 57% patients could complete 6 cycles of chemotherapy. The responses among 34 evaluable patients were complete response (11%), partial response (23%), stable disease (40%) and progressive disease (23%). The hematological toxicities of all grade were seen in 91%, and 68% had grade 3 or 4 hematological toxicity. The median progression-free survival (PFS) and overall survival (OS) was 6 months [95% CI: 3.2-5.7 months] and 8 months [95% CI: 5.3-10.7 months] respectively. The 1-year PFS and OS were 19 % and 34% respectively. Univariate analysis did not show molecular subtype & BRCA status as a significant factor in improving PFS.The number of cycles of GC chemotherapy received ( >/= 3 cycles ) and the Infiltrating Ductal carcinoma histology ( IDC ) was significant in improving PFS, ( HR – 2.4, 95 % CI -1.04-5.67, p value – 0.04 ) & ( HR – 3.23, 95 % CI – 1.47 – 7.06, p value -0.03 ) respectively. Baseline characteristics * 1 metaplastic, 1 Poorly differentiated with neuroendocrine features
Variable n (%) Age Mean - 45.5 yrs; (28 – 68 yrs) Sex Female- 34 (97%) Male- 1 (3 %) Menopausal Status Premenopausal – 26 ( 75 %) Postmenopausal – 8 (23 %) ECOG PS 1- 29 (83 % ) 2– 6 (17% ) Histology IDC- 27 (77 % ) Mixed – 6 (17% ) Others - 2 (6 % ) * Grade Grade III -29 ( 83% ) Grade II – 6 (17% ) Hormone Receptor Status Low ER Positive -7 (20 % ) High ER positive- 6 (17% ) ER negative -22 (63 % ) Low PR positive - 5 (14 % ) High PR positive -3 (9 % ) PR negative- 27( 77 % ) Her 2 neu Positive – 6 (17%) Negative –28 (80 % ) Equivocal-1(3 % ) BRCA BRCA 1 – 6 ( 17% ) Negative – 6(17 % ) Not tested – 23 (66% ) Molecular Subtypes Luminal B -13 ( 37% ) Her 2 enriched -3 ( 9 % ) TNBC -19 ( 54% )
This is the largest study from India on platinum-based chemotherapy in ABC. The real-world outcomes with platinum-based chemotherapy in ABC were PFS 6 months and OS 8 months. On multivariate analysis, patients who completed more than 3 cycles of GC chemotherapy had better survival (p value – 0.003, HR – 3.23, 95 % CI, 1.47 -7.06).
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