Abstract P5-21-09: Oncologist treatment choices in patients with early stage invasive lobular breast carcinoma - a survey

Abstract

Abstract Introduction: Invasive lobular carcinoma (ILC) is common and accounts for 5-15% of all breast cancers. ILC has distinct clinical and histological features that separate it from invasive ductal carcinoma (IDC) with regards to its breast imaging characteristics, patterns of recurrence and sensitivity to systemic therapy. ILC presents challenges to the physician in many aspects of local-regional and systemic therapy choices. We surveyed breast cancer physicians on their beliefs and practice patterns on issues around the management of ILC. Methods: A questionnaire was developed and circulated electronically using a modified Dillman technique to surgical, radiation, and medical oncologists across Canada and Ireland. Results: The questionnaire was completed by 91 of 429 physicians (21% response rate). Response rate by specialty was 25/69 (36%), 21/54 (41%) and 45/306 (13%) for surgical, radiation and medical oncologists respectively. Most surgeon responders (77%) would feel "uncomfortable making treatment decisions for ILC with a mammogram alone" and 100% would be "more comfortable with an MRI". Although 55% reported treating ILC as they would IDC, 22% of surgeons will purposefully obtain larger gross margins intra-operatively. Some radiation oncologists believe ILC is an independent risk factor for local-regional recurrence after breast conserving surgery (49%), and after mastectomy (29%). 33% of radiation oncologists would offer radiation therapy after mastectomy specifically because of the ILC subtype even in the absence of usual indications for radiotherapy. Most medical oncologists treat ILC comparably to IDC with the factors having the largest influence on systemic treatment decisions being tumour stage, hormone receptor status and HER-2 status. 51% of medical oncologists treat ILC with adjuvant chemotherapy as they do for IDC at least ‘most of the time’, while 40% use neoadjuvant chemotherapy as frequently as they do for IDC at least ‘most of the time’. 75% of medical oncologists manage the hormonal treatment of ILC as they do IDC ‘most of the time’ or ‘always’. Conclusions: There remains significant clinical equipoise in the local-regional and systemic management of ILC. This survey has demonstrated wide variations in both beliefs and practices of management for ILC. Clinical guidance, developed on clinical trials specifically assessing the management of ILC, is required. Citation Format: Carmel Jacobs, Mark Clemons, Mohamed FK Ibrahim, Christina Addison, Jean-Michel Caudrelier, Ian D Graham, Brain Hutton, Angel Arnaout. Oncologist treatment choices in patients with early stage invasive lobular breast carcinoma - a survey [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 P5-21-09.