Abstract
Purpose: In current radiotherapy (RT) planning and delivery, population-based dose-volume constraints are used to limit the risk of toxicity from incidental irradiation of organs at risks (OARs). However, weighing tradeoffs between target coverage and doses to OARs (or prioritizing different OARs) in a quantitative way for each patient is challenging. We introduce a novel RT planning approach for patients with mediastinal Hodgkin lymphoma (HL) that aims to maximize overall outcome for each patient by optimizing on tumor control and mortality from late effects simultaneously.Material and Methods: We retrospectively analyzed 34 HL patients treated with conformal RT (3DCRT). We used published data to model recurrence and radiation-induced mortality from coronary heart disease and secondary lung and breast cancers. Patient-specific doses to the heart, lung, breast, and target were incorporated in the models as well as age, sex, and cardiac risk factors (CRFs). A preliminary plan of candidate beams was created for each patient in a commercial treatment planning system. From these candidate beams, outcome-optimized (O-OPT) plans for each patient were created with an in-house optimization code that minimized the individual risk of recurrence and mortality from late effects. O-OPT plans were compared to VMAT plans and clinical 3DCRT plans.Results: O-OPT plans generally had the lowest risk, followed by the clinical 3DCRT plans, then the VMAT plans with the highest risk with median (maximum) total risk values of 4.9 (11.1), 5.1 (17.7), and 7.6 (20.3)%, respectively (no CRFs). Compared to clinical 3DCRT plans, O-OPT planning reduced the total risk by at least 1% for 9/34 cases assuming no CRFs and 11/34 cases assuming presence of CRFs.Conclusions: We developed an individualized, outcome-optimized planning technique for HL. Some of the resulting plans were substantially different from clinical plans. The results varied depending on how risk models were defined or prioritized.
Highlights
The prognosis for patients with Hodgkin lymphoma (HL) with modern combined modality therapy (CMT) is excellent for patients with early stage disease, with 5-year freedom from treatment failure over 85–90% [1,2], and still good for patients with advanced disease, with a 3-year progression free survival (PFS) of around 75% [3]
O-OPT plans generally had the lowest risk, followed by the clinical 34 HL patients treated with conformal RT (3DCRT) plans, the volumetric modulated arc therapy (VMAT) plans with the highest risk with median total risk values of 4.9 (11.1), 5.1 (17.7), and 7.6 (20.3)%, respectively
O-OPT plans were created for 34 patients and compared with clinical 3DCRT plans and VMAT plans
Summary
The prognosis for patients with Hodgkin lymphoma (HL) with modern combined modality therapy (CMT) is excellent for patients with early stage disease, with 5-year freedom from treatment failure over 85–90% [1,2], and still good for patients with advanced disease, with a 3-year progression free survival (PFS) of around 75% [3]. Though modern radiotherapy (RT) approaches such as involved site radiation therapy (ISRT). [10,11,12,13] lead to much lower doses and smaller fields than mantle field irradiation, which was abandoned 15–20 years ago, minimizing the risk of serious long-term effects of RT in each individual patient remains important. The goal of RT planning is to optimize the therapeutic ratio, and population-based dose-volume constraints are used in current clinical practice to limit the risk of adverse effects. Using population constraints may be unreasonable in an individual patient due to the patient’s anatomy relative to the target volume and patient-specific risk factors. For patients with extensive disease, doses close to or exceeding the usual constraints may be accepted if maximum
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