PV QA 4 - Poster Viewing Q&A 4
TU_11_3423 - Assessment of Cardiac Dosimetry and Additional Cardiac Risk Factors in Patients Undergoing Modern Breast Cancer Radiation Therapy
Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3
Assessment of Cardiac Dosimetry and Additional Cardiac Risk Factors in Patients Undergoing Modern Breast Cancer Radiation Therapy
C. Fleming1, G. Kunapareddy2, N. Yu1, R. D. Tendulkar1, S. Cherian1, G. T. Budd2, P. Colier3, and C. S. Shah1; 1Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, 2Department of Medical Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, 3Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH
Purpose/Objective(s): Previous data have demonstrated an association with left breast cancer radiotherapy (RT) and cardiac events; as such, greater focus has been placed on cardiac dosimetry and cardiac sparing techniques. Additionally, the need for long–term cardiac surveillance following breast cancer radiotherapy remains unclear and may be impacted by factors beyond receipt of radiotherapy. As such, an analysis was performed to assess cardiac dosimetry with modern breast cancer RT and to evaluate the presence of additional cardiac risk factors.
Materials/Methods: Breast cancer patients treated between 2014-2017 at a single institution were included in the analysis; all patients received 3-dimensional conformal RT. Patient information included demographic data, cardiac risk factors, RT technique, and dosimetry. Non-treatment cardiac risk factors included hypertension, diabetes, hyperlipidemia, history of coronary artery disease, body mass index > 30, tobacco use, and family history of cardiac disease. Treatment related risk factors included mean heart dose > 4 Gy, and anthracycline/HER2-targeted systemic therapy.
Results: A total of 218 patients were included with a median age of 60 years old. 80 cases (36.7%) were post-mastectomy. The mean heart dose (MHD) for the population (right, left, and bilateral cases) was 1.71 Gy, with increased MHD for left vs right sided radiotherapy (1.68 Gy vs. 0.83 Gy, p=0.03); MHD for bilateral cases (n=10) was 3.15 Gy. For left sided cases, treatment of the internal mammary nodes (IM, n=34) increased MHD from 1.37 to 3.23Gy (p <0.001). Overall, 15 cases (6.9% of all patients) had MHD exceeding 4 Gy. Of these cases, 13 included IM node treatment, representing 86.7% of cases exceeding 4 Gy and 32.5% of all cases where IM nodes were treated. The only factor associated with MHD > 4 Gy was coverage of IM nodes (p<0.001). For those plans with IM coverage, mean heart dose was 2.60Gy with partially wide tangents as compared to 4.63Gy with matched electron fields (p= 0.001). With respect to additional non-treatment cardiac risk factors, 20 patients (9.2%) had no additional risk factors, 40 (18.3%) had 1 additional factor, 46 (21.1%) 2 additional factors, 42 (19.3%) 3 additional factors, 38 (17.4%) 4 additional factors, and 28 (12.8%) 5 or more. When including treatment factors, only 6 patients had no cardiac risk factors, 38 (17.4%) had 1 additional factor, 38 (17.4%) had 2 additional factors, 50 (22.9%) had 3 additional factors, 47 (21.6%) had 4 additional factors, and 39 (17.9%) had 5 or more. During or following treatment, 129 of 218 patients (59.2%) had either an echocardiogram or follow up with a cardiologist.
Conclusion: Mean heart dose with modern radiotherapy techniques was less than 2 Gy using 3D-CRT. Mean heart doses exceeding 4 Gy were primarily seen in cases requiring internal mammary node treatment. Patients undergoing treatment for breast cancer commonly have additional cardiac risk factors, which together may warrant additional post-treatment cardiac follow up.
Author Disclosure: C. Fleming: None. G. Kunapareddy: None. N. Yu: None. G. Budd: None. P. Colier: None. C.S. Shah: Employee; Cleveland Clinic Foundation. Consultant; Impedimed.