Incorporating axillary-lateral thoracic vessel juncture dosimetric variables improves model for predicting lymphedema in patients with breast cancer: A validation analysis

• Published in: Clinical and translational radiation oncology 2023-07, Vol.41, p.100629-100629, Article 100629
• Main Authors: Suk Chang, Jee, Ko, Heejoo, Hee Im, Sang, Sung Kim, Jin, Kyung Byun, Hwa, Bae Kim, Yong, Jung, Wonguen, Park, Goeun, Sun Lee, Hye, Sung, Wonmo, Olson, Robert, Hong, Chae-Seon, Kim, Kyubo
• Format: Article
• Language: English
• Subjects: ALTJ; Breast cancer; Dose-volume histogram; Lymphedema; Original
• ISSN: 2405-6308; 2405-6308
• DOI: 10.1016/j.ctro.2023.100629

•ALTJ was delineated on the CT images of 1,449 patients, and extent of RNI was categorized into as no, limited, and extensive.•ALTJ V35Gy of ≤ 66 % in patients with ≤ 6 removed lymph nodes and ALTJ maximum dose of > 53 Gy in patients with > 15 removed lymph nodes were identified as important according to decision tree analysis.•Model’s C-index increased from 0.84 to 0.90 if dosimetric parameters were included instead of RNI according to the random forest analysis. A relationship between the axillary-lateral thoracic vessel juncture (ALTJ) dose and lymphedema rate has been reported in patients with breast cancer. The purpose of this study was to validate this relationship and explore whether incorporation of the ALTJ dose-distribution parameters improves the prediction model’s accuracy. A total of 1,449 women with breast cancer who were treated with multimodal therapies from two institutions were analyzed. We categorized regional nodal irradiation (RNI) as limited RNI, which excluded level I/II, vs extensive RNI, which included level I/II. The ALTJ was delineated retrospectively, and dosimetric and clinical parameters were analyzed to determine the accuracy of predicting the development of lymphedema. Decision tree and random forest algorithms were used to construct the prediction models of the obtained dataset. We used Harrell’s C-index to assess discrimination. The median follow-up time was 77.3 months, and the 5-year lymphedema rate was 6.8 %. According to the decision tree analysis, the lowest lymphedema rate (5-year, 1.2 %) was observed in patients with ≤ six removed lymph nodes and ≤ 66 % ALTJ V35Gy. The highest lymphedema rate was observed in patients with > 15 removed lymph nodes and an ALTJ maximum dose (Dmax) of > 53 Gy (5-year, 71.4 %). Patients with > 15 removed lymph nodes and an ALTJ Dmax ≤ 53 Gy had the second highest rate (5-year, 21.5 %). All other patients had relatively minor differences, with a rate of 9.5 % at 5 years. Random forest analysis revealed that the model’s C-index increased from 0.84 to 0.90 if dosimetric parameters were included instead of RNI (P