Impact of oncoplasty in increasing breast conservation rates Post neo-adjuvant chemotherapy

Introduction

The essential goal of neoadjuvant chemotherapy (NACT) is to downstage the primary tumor making it amenable for breast conservation surgery (BCS). However, since the safety of this surgery is paramount, post-NACT breast conservation rates remain low. As per the recommendation of the 2018 Early Breast Cancer Trialists' Collaborative Group (EBCTCG) overview of long-term post-NACT follow-up, we have devised a protocol for imaging, localization, rad-path analysis, and documentation of radiotherapy techniques to ensure the safety of post-NACT breast conservation.

Methods

This is a retrospective cohort of 180 breast cancer patients who received NACT and were operated on by a single surgical oncologist from 2015 to 2020. After selection based on published guidelines, patients were treated with neoadjuvant systemic (chemo or hormone) therapy. In cases where primary tumors responded and reduced to 1-2 cm in size mid-NACT, the residual tumors were localized by clips under ultrasound guidance and calcification was wire localized. All patients were treated using appropriate surgical and oncoplastic techniques where indicated. Negative margins were ensured by intra-operative rad-path analysis. Adjuvant chemotherapy and radiotherapy were given as per protocol.

Results

In 81 cases that required mastectomy at presentation, we were able to achieve a 72.8% post-NACT BCS rate with the help of oncoplasty. Overall, 142 of 180 (80%) patients were treated with breast conserving surgery of which 80% (121 of 142) were oncoplasty. Margins were assessed on intra-operative frozen and re-excised in the same setting. No positive margins were reported in final histopath of 142 breast conservation procedures. Post-operative complication rates after breast conservation in the first year were at 17% (24 of 142 including two major complications). Patient reported outcomes were satisfactory with increased satisfaction for breast conservation compared with immediate breast reconstruction.

Discussion

Employing oncoplastic breast surgery (OBS) techniques following stringent protocols for accurate localization of the residual tumor, intra-operative rad-path analysis, and adjuvant treatments, we show successful breast conservation in 72.8% of our mastectomy-qualified patients after downstaging by NACT. We also report satisfactory outcomes for post-NACT surgery, patient-reported satisfaction, and survival.

Abstract LB561: Germline mutational profiling of TNBCs in an Indian cohort

Breast cancer is the most common cancer in Indian women with a high incidence of triple negative breast cancer (TNBC), an aggressive subtype of breast cancer associated with poor prognosis. The high TNBC prevalence (>25%) in India as compared to the western population (10-15%) remains to be a challenge in clinical management. The association of germline BRCA1/2 mutations in TNBCs is well-established as a predisposing factor for hereditary breast cancer risk. However, these studies are predominantly from germline profiling of TNBCs representative of western population. Therefore, we aimed to investigate the germline profiles of breast cancer patients in India using a multi-institutional TNBC cohort based on ACMG consensus multi-gene NGS panel. Of 193 TNBC patients, we identified 57 pathogenic mutations (diagnostic yield = 29.53%) from various genes of which BRCA1 (41/57, 71.93%) and BRCA2 (8/57, 14.03%) were most commonly mutated. We observed a high prevalence of BRCA1 mutations (41/193, 21.24%) and BRCA2 mutations (8/193, 4.14%) in our cohort as compared to published literature. Additionally, 8 pathogenic mutations were also reported in non-BRCA cancer pre-disposing genes associated with the HR pathway like ATM, CHEK2, PALB2. 10 novel mutations were identified in 3 genes namely BRCA1, BRCA2 and PALB2. The most common type of mutations was found to be frame-shift which may cause protein truncation and loss of function. Furthermore, we identified 48 variants of unknown significance (24.9%) of which about 7% were in the BRCA1/2 genes. Data mining from global databases like TCGA, Genome Asia indicated that the novel mutations were unique to the Indian population compared to the germline profiles of different ethnicities. Our study confirms the major contribution of BRCA1/2 genes in TNBCs as reported in the literature. A high percentage of the women were found to be associated with young age onset which may be attributed to BRCA mutations. We have also assessed the association of clinicopathological parameters such as tumor grade, stage, recurrence to the germline mutational status. Our analysis shows significant association of germline mutational status with family history thus underlin the importance of multi-gene panel testing as recommended by NCCN guidelines. Moreover, our results also emphasize the need for designing/implementing guidelines specific to Indian population. In summary our results indicate that Indian TNBCs have a high prevalence of BRCA1/2 mutations. Large scale studies in future are warranted to validate these preliminary findings.

Citation Format: Chaitanyanand Koppiker, Ashwini Bapat, Siddharth Gahlaut, Naveen Luke, Jisha John, Rupa Mishra, Aishwarya Konnur, Namrata Namewar, Ruhi Reddy, Shaheen Shaikh, Rituja Banale, Smeeta Nare, Laleh Busheri, Asha Reddy, Ashraf Mannan, Sabarinathan Radhakrishnan, Selvi Radhakrishna, Santosh Dixit. Germline mutational profiling of TNBCs in an Indian cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB561.

Breast cancer biobank from a single institutional cohort in an urban setting in india: Tumor characteristics and survival outcomes

BACKGROUND

A breast cancer biobank with retrospectively collected patient data and FFPE tissue samples was established in 2018 at Prashanti Cancer Care Mission, Pune, India. It runs a cancer care clinic with support from a single surgeon's breast cancer practice. The clinical data and tissue sample collection is undertaken with appropriate patient consent following ethical approval and guidelines.

METHODS

The biobank holds clinical history, diagnostic reports, treatment and follow-up information along with FFPE tumor tissue specimens, adjacent normal and, in few cases, contralateral normal breast tissue. Detailed family history and germline mutational profiles of eligible and consenting patients and their relatives are also deposited in the biobank.

RESULTS

Here, we report the first audit of the biobank. A total number of 994 patients with breast disease have deposited consented clinical records in the biobank. The majority of the records (80%, n = 799) are of patients with infiltrating ductal carcinoma (IDC). Of 799 IDC patients, 434 (55%) have deposited tumor tissue in the biobank with consent. In addition, germline mutation profiles of 84 patients and their family members are deposited. Follow-up information is available for 85% of the 434 IDC patients with an average follow-up of 3 years.

CONCLUSION

The biobank has aided the initiation of translational research at our center in collaboration with eminent institutes like IISER Pune and SJRI Bangalore to evaluate profiles of breast cancer in an Indian cohort. The biobank will be a valuable resource to the breast cancer research community, especially to understand South Asian profiles of breast cancer.

Abstract PO008: Stromal Tumor Infiltrating Lymphocytes (sTILs) as a putative prognostic marker to identify a responsive subset of TNBC in an Indian Breast Cancer Cohort

Objectives: Prognostic significance of stromal tumor infiltrating lymphocytes; sTILs is evaluated to identify a responsive subset of TNBC in an Indian cohort of breast cancer patients. Methods: A retrospective cohort of breast cancer patients from a single onco-surgeon breast cancer clinic treated with uniform treatment strategy across is evaluated for sTILs. FFPE tissue of primary tumor of invasive breast carcinoma are collected with ethical approvals. Tumor sections blinded for subtypes are stained with H&E and scored for sTILs by a pathologist following Immuno-Oncology TILs working groups scoring guidelines. Results: Analysis of 144 primary breast tumors for sTILs scores re-enforces significantly higher infiltration in TNBC tumors than HER2+ve and ER+ve tumors. Higher sTILs scores co-relate with gradually incremental pathological response to therapy specifically in TNBC subset and with better disease-free survival outcomes. Within TNBC, older and post-menopausal patients harbor higher scores of sTILs. Conclusion: Despite a small cohort of breast cancer patients, TNBC subtype reflected significantly higher scores of sTILs with better response to therapy and disease-free outcomes as compared to other breast cancer subtypes. A larger number of breast cancer patients from an Indian cohort will strengthen the findings to establish sTILs as a marker to identify a responsive subset of TNBC.

Citation Format: Madhura Kulkarni, Pooja M. Vaid, Anirudha Puntambekar Puntambekar, Rituja A. Banale, Ruhi Reddy, Rohini Unde, Namrata Namewar, Devaki Kelkar, L.S. Shashidhara, C.B. Koppiker. Stromal Tumor Infiltrating Lymphocytes (sTILs) as a putative prognostic marker to identify a responsive subset of TNBC in an Indian Breast Cancer Cohort [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PO008.