Is clinical target volume necessary?—a failure pattern analysis in patients with locally advanced non-small cell lung cancer treated with concurrent chemoradiotherapy using intensity-modulated radiotherapy technique

Abstract

Background: Our previous dosimetric study showed that for locally advanced non-small cell lung cancer (LA-NSCLC), radiotherapy with intensity-modulated radiotherapy (IMRT) technique could deliver sufficient dose coverage to subclinical regions and reduce the dose to normal tissues with the omission of clinical target volume (CTV). To further clinically validate this strategy, we conducted the current study to analyze the failure pattern for patients with LA-NSCLC treated with concurrent chemotherapy and CTVomitted IMRT. We also investigated the effects of target volumes on lymphopenia during radiotherapy to further test the potential benefits of CTV omission in anti-tumor immunotherapy.Methods: A total of 63 patients with LA-NSCLC treated with CTV-omitted IMRT with concurrent chemotherapy were enrolled in this study. Their planning target volume (PTV) (also PTV-g) was expanded directly from gross tumor volume (GTV). A virtual CTV was expanded from GTV, and the PTV generated from virtual CTV was named planning target volume with CTV expansion (PTV-c). Treatment failures were divided into local, regional, and distant failures, and local-regional recurrences were classified into inside PTV-g (IN-PTV-g), between PTV-g and PTV-c (PTV-g-c), and outside PTV-c (OUT-PTV-c). The relationship between lymphopenia during radiotherapy and the target volumes was also evaluated using Spearman's correlation analysis.Results: Among the 60 patients with detailed follow-up data for recurrences, 46 (76.7%) experienced recurrences, with 18 (30.0%) being local recurrence, 5 (8.4%) being regional failure, and 33 (55.0%) being distant failure. For the 21 patients with local-regional recurrences, 16, 6, and 1 were IN-PTV-g, OUT-PTV-c, and PTV-g-c recurrences, respectively. Lymphopenia during radiotherapy was associated with both GTV and PTV, with larger volumes linked to severe lymphopenia.Conclusions: CTV omission is feasible for LA-NSCLC treated with concurrent chemoradiotherapy and does not compromise failure inside the subclinical region. The radiation volumes were associated with lymphopenia during radiotherapy, with larger volumes related to severe lymphopenia. This finding supports the further exploration of CTV omission for immunotherapy.

Global research landscape and trends of cancer radiotherapy plus immunotherapy: A bibliometric analysis

“…Further studies are needed to find the most immunogenic SABR doses to be used in combination with immunotherapy. Modern radiation modalities have created conditions to reduce the dose of organs at risk (OARs), to adaptively replan, to reduce the PTV, and to perform CTV-omitted RT, and elective nodal RT [ 91 , 145 , 146 ]. The safety and efficacy of CTV-omitted RT and elective nodal RT merits future studies.…”

Low versus high dose of postoperative radiotherapy for locally advanced esophageal squamous cell carcinoma: a propensity score‐matched analysis

“…Previous studies have shown that irradiation of the mediastinal lymph nodes may lead to lymphopenia, which could further lower immunity and affect prognosis. 16,17 Therefore, we speculated that a high dose of postoperative radiotherapy might lead to more toxicities and lower immunity, and these factors may have contributed to the poor prognosis of the high-dose group.…”

Pattern of failure and clinical value of local therapy for oligo‐recurrence in locally advanced non‐small cell lung cancer after definitive chemoradiation: Impact of driver mutation status

“…The specific implementation process of radiotherapy plan, dose requirements for treatment planning, and radiation techniques are described elsewhere. 26 Definitive CRT was defined as two or more cycles of platinum‐based chemotherapy concurrently or sequentially with curative thoracic radiotherapy (54–66 Gy), wherein the mean dose to the lung was <20 Gy, V20 (the volume of the lung parenchyma that received 20 Gy or more) was <35%, or both. Patients receiving corresponding TKIs in addition to definitive CRT, before disease recurrence, were allowed and those receiving durvalumab consolidation were excluded.…”

“…Patients with pathologically confirmed NSCLC, determined to be inoperable with locally advanced NSCLC generally through multidisciplinary discussions, treated with definitive CRT, and had their tumor tissue tested for the status of common driver genes (including EGFR, ALK, and ROS1) at the Department of Pathology of the Fudan University Shanghai Cancer Center from January 2013 to March 2021 were retrospectively enrolled. The specific implementation process of radiotherapy plan, dose requirements for treatment planning, and radiation techniques are described elsewhere 26 . Definitive CRT was defined as two or more cycles of platinum‐based chemotherapy concurrently or sequentially with curative thoracic radiotherapy (54–66 Gy), wherein the mean dose to the lung was <20 Gy, V20 (the volume of the lung parenchyma that received 20 Gy or more) was <35%, or both.…”

“…The specific implementation process of radiotherapy plan, dose requirements for treatment planning, and radiation techniques are described elsewhere. 26 Definitive CRT was defined as two or more cycles of platinum-based chemotherapy concurrently or sequentially with curative thoracic radiotherapy (54-66 Gy), wherein the mean dose to the lung Conclusion: LA-NSCLC patients receiving definitive CRT generally had similar PFS and pattern of treatment failure, regardless of driver mutation status.…”