Abstract P4-11-42: Pathological response and its impact on survival with neoadjuvant chemotherapy according to intrinsic subtype in locally advanced breast cancers in North India: Is it different from the West?
Authors: Agrawal Sushma , Lal Punita , Kumar Shaleen 
Published: May 2015

Background: Breast cancer patients commonly present in locally advanced stage (LABC) in our country .We propose to correlate the pathological response to neoadjuvant chemotherapy (NACT) and its impact on survival based on the intrinsic subtype of breast cancer in our population. Materials and methods: Consecutive patients of LABC who underwent NACT (taxane and or anthracyclines based )followed by definitive surgery and radiotherapy during the period January 2007 to December 2012 were grouped on the basis of intrinsic subtypes of tumor (Luminal A, Luminal B, Her-2 Type, Basal). The pathological response to NACT in tumour as well as axillary nodes [complete response (pCR), partial response (pPR)] was correlated with the disease free survival (DFS) and overall survival (OS)at 5 years in the four intrinsic subtypes using Kaplan Meier Analysis. Results: 208 patients were the subject of this analysis. The median age of patients was 46 years (range 24-81 years), 46% were premenopausal and 54% postmenopausal, 42% right sided and 58% left sided. The clinical prechemotherapy status of tumour and node at presentation was 15% T2, 40% T3, 45% T4 (9% T4a, 35% T4b, 1% T4c) 8% N0, 42% N1, 41% N2, 9% N3.The intrinsic subtype of our population at presentation was Luminal A (16%), Luminal B (23%), Her-2 Type (23%), Basal (37%).The overall pCR rate to NACT in tumour and in node was 31% and 45%.The pCR rate in tumour according to intrinsic subtype was 26%, 23%, 39% and 31.5% in Luminal A, Luminal B,Her-2 Type and Basal type respectively. The pCR rate in node was 26%, 38%, 41.6% and 59% in Luminal A, Luminal B,Her-2 Type and Basal type respectively. At a median followup of 34 months (range 6-84 mo)the 5 year DFS and OS was significantly higher in patients achieving pCR tumour or pCR node in Her-2 type and Basal subtype (Table 1).

pCR rate and Impact of pCR (Tumour and node) according to intrinsic subtype on 5 yr DFS and OSIntrinsic SubtypepCR(Tumour)(%)pCR(Node)(%)DFS (% at 5yr)(pCR tumor vs pPR tumor)(pvalue)DFS (% at 5yr)(pCR node vs pPR node)(pvalue)OS (% at 5yr)(pCR Tumour vs pPR tumor)(p value)OS (% at 5yr)(pCR Node vs pPR node)(p value)Luminal A2626100 vs 67 (0.08)88 vs 70 (0.49)100 vs 72 (0.1)85 vs 75 (0.7)Luminal B233868 vs 56 (0.9)87 vs 32 (0.11)80 vs 57 (0.9)85 vs 35 (0.35)Her-2 Type3941.690 vs 44 (0.003)83 vs 45 (0.009)87 vs 59 (0.02)90 vs 66 (0.03)Basal31.55985 vs 50 (0.004)46 vs 50 (0.26)83 vs 50 (0.02)975 vs 60 (0.19)pCR(pathological CR),pPR(pathological PR)

Conclusions: The pCR rate to NACT in tumour or node seems to be considerably higher in our population in Her-2 and basal subtypes than that reported in the western literature. pCR (tumour as well as node) as a surrogate for both DFS and OS at 5 years in Her-2 and basal subtypes of breast cancer has been validated.

Citation Format: Sushma Agrawal, Punita Lal, Shaleen Kumar. Pathological response and its impact on survival with neoadjuvant chemotherapy according to intrinsic subtype in locally advanced breast cancers in North India: Is it different from the West? [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-11-42.