Feasibility study of individualized optimal positioning selection for left‐sided whole breast radiotherapy: DIBH or prone

Abstract

The deep inspiration breath hold (DIBH) and prone (P) position are two common heart‐sparing techniques for external‐beam radiation treatment of left‐sided breast cancer patients. Clinicians select the position that is deemed to be better for tissue sparing based on their experience. This approach, however, is not always optimum and consistent. In response to this, we develop a quantitative tool that predicts the optimal positioning for the sake of organs at risk (OAR) sparing. Sixteen left‐sided breast cancer patients were considered in the study, each received CT scans in the supine free breathing, supine DIBH, and prone positions. Treatment plans were generated for all positions. A patient was classified as DIBH or P using two different criteria: if that position yielded (1) lower heart dose, or (2) lower weighted OAR dose. Ten anatomical features were extracted from each patient's data, followed by the principal component analysis. Sequential forward feature selection was implemented to identify features that give the best classification performance. Nine statistical models were then applied to predict the optimal positioning and were evaluated using stratified k‐fold cross‐validation, predictive accuracy and receiver operating characteristic (AUROC). For heart toxicity‐based classification, the support vector machine with radial basis function kernel yielded the highest accuracy (0.88) and AUROC (0.80). For OAR overall toxicities‐based classification, the quadratic discriminant analysis achieved the highest accuracy (0.90) and AUROC (0.84). For heart toxicity‐based classification, Breast volume and the distance between Heart and Breast were the most frequently selected features. For OAR overall toxicities‐based classification, Heart volume, Breast volume and the distance between ipsilateral lung and breast were frequently selected. Given the patient data considered in this study, the proposed statistical model is feasible to provide predictions for DIBH and prone position selection as well as indicate important clinical features that affect the position selection.

Deep-inspirational breath-hold (DIBH) technique in left-sided breast cancer: various aspects of clinical utility

“…It was found that larger total lung volume increase predisposed to more significant DIBH-related heart and LAD dose reductions. Lin et al found that in comparison to FB, DIBH resulted larger benefit in heart and LAD doses during postmastectomy RT than during WBI [ 27 ]. No similar relationship could be seen in our study; in this patient cohort heart and LAD dose reductions were weakly correlated with DIBH-related lung volume increases, and none of the studied parameters seemed to have predictive power.…”

Identifying breast cancer patients who gain the most dosimetric benefit from deep inspiration breath hold radiotherapy

“…They reported that a longer cardiac contact distance, the higher the heart dose. Lin and colleagues 10 investigated a variety of anatomical factors in 16 patients including breast and heart volumes and heart in field and reported that the development of a predictive model is challenging for these patients. Similarly, Ledsom et al 9 and Czeremszynska et al 6 could not identify specific characteristics or thresholds that could accurately identify patients who would benefit most from DIBH despite finding correlations between patient related and dosimetric parameters.…”

“…stage, smoking status, co-morbidities and radiation prescription. DIBH technique-specific factors investigated in previous studies as potential factors associated with reduction in heart and lung dose were also collected, 6,[8][9][10][11][12][13][14][15][16][17][18] and are provided in Table 2. Multiple heart, lung and LAD doses were recorded from both the FB and DIBH plans ( Table 2).…”

“…To date, various potential patient and radiation therapy technique-specific factors have been investigated as potential predictors of mean heart dose reduction. 6,[8][9][10][11][12][13][14][15][16][17][18] While these studies have all compared heart doses on free breathing (FB) versus DIBH planning computed tomography (CT) scans of left-sided breast cancer patients receiving radiation therapy to their whole breast or chest wall, predictive factors identified have varied. The aim of this study was to investigate if any factors existed that could identify breast cancer patients who may benefit most from DIBH, to develop a cardiac dose risk profile approach to facilitate appropriate utilisation of departmental resources.…”

“…To date, various potential patient and radiation therapy technique‐specific factors have been investigated as potential predictors of mean heart dose reduction 6,8–18 . While these studies have all compared heart doses on free breathing (FB) versus DIBH planning computed tomography (CT) scans of left‐sided breast cancer patients receiving radiation therapy to their whole breast or chest wall, predictive factors identified have varied.…”