Late onset toxicities associated with the use of CDK 4/6 inhibitors in hormone receptor positive (HR+), human epidermal growth factor receptor-2 negative (HER2-) metastatic breast cancer patients: a multidisciplinary, pan-EU position paper regarding their optimal management. The GIOCONDA project

The personalization of therapies in breast cancer has favoured the introduction of new molecular-targeted therapies into clinical practice. Among them, cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors have acquired increasing importance, with the approval in recent years of palbociclib, ribociclib, and abemaciclib in combination with endocrine therapy. Currently, no guidelines are available to monitor and manage potential long-term toxicities associated with the use of these drugs. A multidisciplinary panel of European oncologists, was supported by a pharmacologist, a hematologist, a hepatologist and a pulmonologist to discuss the management of long-term toxicities, based on the literature review and their clinical experience. The panel provided detailed roadmaps to manage long-term toxicities associated with the use of CDK4/6 inhibitors in clinical practice. Knowing the frequency and characteristics of the toxicity profile associated with each CDK4/6 inhibitor is important in the decision-making process to match the right drug to the right patient.

Abstract P1-01-01: Systemic imaging fails to detect metastasis in early stage breast cancer

Background: Current NCCN guidelines for early stage breast cancer (Stage I and II) do not recommend routine systemic imaging in the absence of symptoms or abnormal labs suggestive of distant metastasis. This study aims to determine the frequency and appropriateness of these imaging studies performed, its impact on staging and the factors that influence physicians in ordering these imaging studies.

Methods: Patients with stage I and II breast cancer at initial presentation were retrospectively identified between years 2011-2015 from the tumor registry. Charts were reviewed to determine patients who got systemic imaging (CT scan, non-breast MRI, bone scan or PET scan) within 6 months of diagnosis. Provider notes and laboratory data were analyzed to establish the appropriateness of ordered imaging studies and if the imaging altered the stage. For each patient in the study, age at diagnosis, the grade of the breast tumor, hormonal receptor status and HER-2 status was documented. Statistical analysis was done using appropriate tests.

Results: A total of 1067 patient charts were screened, of which 882 were identified for inclusion in the study (544 stage I, 338 stage II). Amongst the cohort, 18.57% (101) of patients with stage I and 50.89% (172) of patients with stage II cancer received imaging studies within the first 6 months of diagnosis. Only 12.68% (69) of stage I patients and 18.24% (62) of stage II patients were judged appropriate for imaging based on symptoms and lab results suggesting metastasis. In the imaged cohort of Stage I patients, only 4.35% (3) of the appropriately imaged group and 13.33% (4) of the inappropriately imaged group had a change in stage. Similarly, in the Stage II cohort, only 4.84% (3) of the appropriately imaged group and 8.18% (9) of the inappropriately imaged group saw a change in state. The difference in stage change in the appropriately and inappropriately imaged groups was not statistically significant. (p = 0.11 for Stage I, p=0.41 for Stage II). Only 5.9% of Stage I and 2.9% of Stage II imaged patients changed to stage IV. Grade 1 patients were less likely to receive systemic imaging than grade 2 and 3 patients ((p <0.001). Similarly, the difference in imaging rates ordered in patients with ER and/or PR negative status versus ER and PR positive status was significant (p=0.0004). Triple negative (p <0.001) status and age≤ 50 years were statistically significant predictors of patients receiving imaging (p = 0.014). HER-2 status alone was not a significant predictor of getting imaged (p= 0.527).

Conclusions: We performed the first ever study to investigate a correlation between the appropriateness of ordered imaging studies in early stage breast cancer and its ability to detect a change in stage. Distant metastasis identification among stage I & II patients was extremely rare among both appropriately and inappropriately imaged groups. Our findings suggest a wide prevalence of inappropriately ordered imaging studies in Stage I and II breast cancer as well as limited utility for even appropriately ordered ones. Further, other factors such as grade of the tumor, ER/PR/HER2 status and age were found to be statistically significant predictors of whether patients received imaging studies.

Citation Format: Gaba AG, Kraft R, Stjern BK, Monu M, Gunderson MA, Hanish C, Samreen A, Paladugu G. Systemic imaging fails to detect metastasis in early stage breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-01-01.