Abstract P3-12-04: Analysis of radiation dose to the shoulder by treatment technique and correlation with patient reported outcomes in patients receiving regional nodal irradiation
Authors: Bazan JG , Dicostanzo D , Hock K , Healy E , Beyer S , White JR 
Published: May 2019

Background: Shoulder/arm morbidity is a late complication of breast cancer treatment. Postmastectomy radiation therapy (PMRT)/regional nodal irradiation (RNI) increases dose to the muscles and soft tissues of the shoulder and upper neck and back. Most patients are treated with 3D conformal radiation therapy (3DCRT) or Intensity modulated radiation therapy (IMRT). Here, we set to analyze the impact of 3DCRT vs. IMRT on radiation dose to the shoulder, and to retrospectively explore the relationship of treatment technique on long term patient-reported outcomes in the subset of patient who had completed the quick Disabilities of the Arm, Shoulder, and Hand (q-DASH) questionnaire.

Materials/Methods: We identified consecutive patients in our department treated with PMRT/RNI for curative intent from 2013-2016. We excluded patients treated for recurrent disease, those with metastatic disease, and those with unresected disease in the supraclavicular (SCV) fossa and/or axillary apex requiring a radiation boost to that area. We contoured the shoulder as all of the muscles/soft tissue/bone from 2 cm above the ipsilateral SCV planning target volume (PTV) to the cranial aspect of the breast or chestwall PTV. No planning constraints were set for the shoulder since this was retrospectively contoured. We used the dose volume histogram to determine the volume of shoulder receiving at least 5 Gy, 10 Gy,...,50 Gy (V5-V50, respectively). We identified patients that completed a q-DASH questionnaire ≥6 months from the end of PMRT/RNI. Descriptive statistics were used to summarize the shoulder dose and q-DASH values. Differences between groups were assessed by the t-test or chi-square test with p&lt;0.05 considered significant.

Results: We found 237 patients treated with PMRT/RNI with median age of 52 y (IQR 44-60 y), 75% treated with mastectomy, 85% had axillary lymph node dissection (ALND), median of 18 nodes removed (IQR 12-26). All patients received 50 Gy/25 fractions. A total of 68 patients (28.7%) were treated with IMRT. IMRT significantly reduced the V20-V50 to the shoulder vs. 3DCRT (e.g., V45Gy=21.7 mL vs. 208.4 mL, p&lt;0.0001). Of the 237 patients, 66 had completed a q-DASH at least 6 months from the end of radiation therapy (median, 14.5 months). Patients that completed the q-DASH vs. not were similar in age (p=0.29), number of nodes removed (p=0.17), use of ALND (p=0.13), use of chemotherapy (p=0.49) and use of mastectomy (p=0.22). The median (IQR) and mean (SD) q-DASH were 20.5 (6.8-38.6) and 24.3 (20.2) for all patients; 20.5 (9.1-38.6) and 24.1 (19.4) for the 53 mastectomy patients; 18.2 (4.5-45.5) and 25.2 (24.2) for the 13 lumpectomy patients. Most patients (N=49) were treated with 3DCRT. Compared to patients treated with 3DCRT, IMRT patients had a trend towards lower q-DASH mean scores: 16.9 vs. 26.9, p=0.077.

Conclusion: In summary, we found that IMRT reduces radiation dose to the shoulder and is associated with a trend towards reduced q-DASH scores at least 6 months after PMRT/RNI in a subset of our cohort. These results support prospective evaluation of IMRT as a technique to reduce shoulder morbidity in breast cancer patients receiving PMRT/RNI.

Citation Format: Bazan JG, Dicostanzo D, Hock K, Healy E, Beyer S, White JR. Analysis of radiation dose to the shoulder by treatment technique and correlation with patient reported outcomes in patients receiving regional nodal irradiation [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 P3-12-04.