Abstract PS14-23: Reconsidering the management of palpable DCIS - A single institution audit

Background: Ductal carcinoma in situ (DCIS) identified by screening mammography accounts for 20% of breast cancer diagnoses, and microinvasion (DCIS-M) is found in 5%-10%. There are no defined treatment guidelines for palpable DCIS or DCIS-M. The role of screening mammography is now being questioned across the world and in the developing world with no national screening programs, women with DCIS present with a palpable lump in the breast. We conducted a retrospective audit of women with DCIS treated at our institution to classify palpable DCIS and DCIS-M as distinct clinical stages and emphasize the need for a change in management of ‘palpable DCIS’ Methods: Annually we register approximately 1700 new cases of early breast cancer of which DCIS and DCIS-M constitutes less than 1%. Between 2005-2016 we registered 784 cases of with DCIS, DCIS-M and early invasive cancer with extensive intraductal component (EIC) at our centre. A retrospective analysis of these cases was performed. Results: Of the 784 patients case records reviewed, 113 (14.4%) had Tis, 87 (11.1% of all early cases and 43.5% of DCIS) had T1mic, the rest had invasive cancer with EIC, of which 46 (5.9%) wereT1a, 28(3.6%) were T1b, 146 (18.6%) were T1c and 364 (46.4%) wereT2. The median age at presentation was 48 years, median clinical tumour size was 3cm; 740 (94.4%) presented with palpable breast lumps.At a median follow up of 86 months , the disease free survival was 95.6% for Tis, 96.6% T1mic, 90.5% T1 and 82.7% T2 (p=0.00). On follow up distant recurrences were noted in 5(4.4%) patients with Tis, 3(3.4%) with T1mic, 21(9.5%) with T1 and 63(17.3%) with T2, (p=0.00). Limited use of adjuvant chemotherapy in Tis and T1mic may have contributed to the high distant recurrences in that group. Also palpable Tis,T1mic and T1a had higher percentage of HR negative compared to those with larger invasive tumours. Conclusions: DCIS presenting in palpable lesions poses a clinical dilemma for the use of adjuvant therapy. In our cohort 43.5% of the palpable DCIS showed evidence of microinvasion with high risk of distant recurrence compared to screen detected DCIS. We thus need to reconsider grossing techniques to accurately identify foci of invasion, redefine DCIS-M based on number and size of foci of invasion and explore the possible role of adjuvant chemotherapy in treating large palpable DCIS. Citation Format: Karishma Kirti, Nita Nair, Tanuja Shet, Rohini Hawaldar, Vani Parmar, Seema Gulia, Shalaka Joshi, Sridevi Murali, Vaibhav Vanmali, Bipin Bandre, Sudeep Gupta, Rajendra Badwe. Reconsidering the management of palpable DCIS - A single institution audit [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS14-23.