Residual cancer burden (RCB) profiling of post neoadjuvant therapy breast cancer resections in a tertiary cancer care hospital

• Author Details:   
• Shweta Ashok Deulkar ^*
• Meena Pangarkar
• Radhika Praveen Pagey
• Shraddha Rajan Mahindra
• Yogita Devi
• Anand Pathak

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Background: Neoadjuvant therapy (NAT) has become a standard of care for locally advanced breast cancers. It is also considered for tumours which are large (> 2cm). This shift in treatment paradigm has brought major benefits in care for breast cancer patients in terms of long term prognosis. To calculate the response after NAT, MD Anderson has developed a scoring system which has shown a great concordance between RCB class & prognosis. This study aims to categorise breast cancer patients in different RCB groups based on their score. It also aims to correlate each score group with clinicopathological features & to profile RCB scoring amongst different molecular subtypes in Indian scenario.

Materials and Methods: This was a 5 year retrospective study carried out in the department of Surgical Pathology in a tertiary cancer care hospital. Grossing of resection specimens & microscopic examination were done according to CAP protocol & included residual tumour size, histological grade, lymphovascular space invasion, nodal metastasis with size of metastatic focus, fibrosis, calcification, histiocytes and necrosis.

Results: The highest number of pathological complete response was seen in the Her 2 enriched subtype (46.15%) followed by Luminal B Her2 positive subtype (34.48%), then TNBC subtype (31.08%). LA subtype had the lowest response rate (11.11%).

Conclusions: Different molecular subtypes of Breast carcinoma show different grades of response to NAT. The highest frequency of pathologic complete response (PCR) was seen in the Her 2 neu enriched subtype, followed by the Luminal BH subtype.

Keywords: Molecular subtypes, Residual cancer burden, Neoadjuvant therapy, Breast carcinoma, Pathologic complete response (PCR).