Abstract P4-11-33: Continuous glucose monitoring and hyperglycemia during chemotherapy for early-stage breast cancer
Authors: Accordino Melissa K , Spivack John H , Ulene Sophie , Honan Erin , Trivedi Meghna S , Crew Katherine D , Harden Erik , Law Cynthia , Hershman Dawn L 
Published: March 2022

Background: There are a growing number of breast cancer (BC) survivors who are at risk for short and long-term treatment-related toxicities. BC survivors may be at higher risk of developing diabetes mellitus (DM), and chemotherapy may potentiate this risk due to concurrent corticosteroid use. DM is associated with both short and long-term treatment toxicities and worse BC outcomes. The prevalence of hyperglycemia (HG) during chemotherapy for early-stage BC (ESBC), and the association between HG during chemotherapy and treatment-related toxicities is unknown. Methods: We are conducting a single-arm pilot study to evaluate the prevalence of hyperglycemia among patients with ESBC during chemotherapy (NCT04473378). Patients are eligible if ≥18 years old, initiating chemotherapy with corticosteroid use, not receiving systemic steroids except as supportive care for chemotherapy, and known DM is allowed if patients are not treated with insulin. Within 7 days of chemotherapy initiation, the Freestyle Libre Pro (Abbott Diabetes Care) continuous glucose monitoring system is applied to the posterior arm of each participant. Patches are reapplied every 2-3 weeks and worn continuously until chemotherapy completion (duration per regimen). The Freestyle Libre Pro monitors interstitial glucose every 15 minutes via subcutaneous sensor filaments adhered to the skin without a finger prick. Data is downloaded using a wireless scan of the sensor by a reader. The primary endpoints are: 1) the prevalence of HG, defined as the number of participants who have ≥1 glucose value (fasting or non-fasting) of ≥140 mg/dL at any point from chemotherapy initiation to completion; 2) Among participants who develop HG, the proportion of time in which they have HG, measured as the number of hyperglycemic values (glucose value of ≥140 mg/dL) divided by the total number of glucose values recorded in an individual for the duration of chemotherapy. Secondary endpoints include the prevalence of impaired glucose tolerance (hemoglobin A1c [HgbA1c] ≥5.7%) prior to chemotherapy initiation in patients without a history of DM, and changes in glucose biomarkers (HgbA1c, fructosamine, and serum creatinine) during treatment. Results: Between December 2020 and April 2021, 7 patients were enrolled, with evaluable data for 5 patients. At baseline median age was 60 (range, 37-74) and median BMI was 33.0 (range, 24.6-41.6). Chemotherapy regimens were: docetaxel/cyclophosphamide (40%); docetaxel/cyclophosphamide/trastuzumab/pertuzumab (20%); weekly paclitaxel (20%); and paclitaxel followed by doxorubicin/cyclophosphamide (20%). All patients (100%) developed hyperglycemia. Of 18,768 sensor readings (281,265 minutes) the proportion of time participants were hyperglycemic (≥140 mg/dL) during the period of adjuvant/neoadjuvant chemotherapy was 22.1%, and the mean time from first corticosteroid administration to first hyperglycemic episode was 7.6 hours. Of three patients with no history of DM (including one patient with glucose intolerance), the proportion of time spent hyperglycemic (≥140 mg/dL) was 9.9% (range, 1.7-13.8%), and the mean daily glucose was 106.7 mg/dL (SD 10.3). Of the two patients with DM, the proportion of time spent hyperglycemic was 70.2% (range, 67.2-79.5%) and the mean daily glucose was 171.7 mg/dL (SD 3.1). Changes in glucose biomarkers will be presented with the full cohort. Conclusion: Hperglycemia during chemotherapy occurred in 100% of the cohort, including those without a history of DM or glucose intolerance. It is currently unknown if HG during chemotherapy is a modifiable risk factor for short and long-term BC treatment toxicities including neuropathy. Understanding glucose trends in this setting will help determine a successful intervention for HG during chemotherapy which may reduce short and long-term treatment toxicities.

Citation Format: Melissa K Accordino, John H Spivack, Sophie Ulene, Erin Honan, Meghna S Trivedi, Katherine D Crew, Erik Harden, Cynthia Law, Dawn L Hershman. Continuous glucose monitoring and hyperglycemia during chemotherapy for early-stage breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-11-33.