Intensity-Modulated Radiotherapy versus 3-Dimensional Conformal Radiotherapy Strategies for Locally Advanced Non-Small-Cell Lung Cancer

Abstract

In the evolution of radiation oncology technology, improved planning and treatment delivery advanced from two-dimensional radiotherapy (2DRT) to three-dimensional conformal radiotherapy (3DCRT) two decades ago. In the last decade, intensity-modulated radiation therapy (IMRT) emerged in addition to daily image guidance and fourdimensional (4D) image-based motion management (1). Chemoradiotherapy, which was actually established mainly with a 2DRT trial-RTOG 9410, is the current standard of care in patients with inoperable stage IIIA or IIIB non-small cell lung cancer (NSCLC) when compared to sequential protocols (2-7). Currently, aggressive chemoradiotherapy is the standard, and is well accepted in highly selected septuagenarians with inoperable stage IIIB NSCLC (8). Conventional doses (60-63 Gy) of 3DCRT were well-thought-out not enough to succeed for desired local control to avoid dismal survival. There has been a significant challenge in safely escalating the radiation dose over 60 Gy, while preserving the critical organ at risk (OAR) structures (9-12). In the last decade, IMRT has been the leading improvement, and has been considered as the key solution for safe dose escalation and delivery. Other accompanying challenges are the fight with unpredictable movement of the tumor during the respiratory phases, the need to increase the accuracy of treatment delivery during each fraction, and the necessity to clarify the heterogeneity correction in treatment planning systems. The newest technology has been improved upon in recent years by 4D image-based motion capturing and the management of treatment planning, the evolution of calculation algorithms in treatment planning systems that are capable of better estimating the dose delivery to tumors and normal structures, and image-guided radiotherapy. All of these improvements increased the daily setup accuracy. There is a requirement for radiotherapy is evident in NSCLC, with than 60% of these patients requiring radiotherapy during treatment, and more than 40% of patients who receive radiotherapy receive it during the initial treatment (13,14). Therefore, due to the growing struggle with lung cancer, the current debate, based on inclusion of all modern technology, is whether IMRT has an advantage over 3DCRT in the outcomes of local control, surChemoradiotherapy is the current standard of care in patients with advanced inoperable stage IIIA or IIIB non-small cell lung cancer (NSCLC). Three-dimensional radiotherapy (3DCRT) has been a trusted method for a long time and has well-known drawbacks, most of which could be improved by Intensity Modulated Radiotherapy (IMRT). IMRT is not currently the standard treatment of locally advanced NSCLC, but almost all patients could benefit to a degree in organ at risk sparing, dose coverage conformality, or dose escalation. The most critical step for a radiation oncology department is to strictly evaluate its own technical and physical capabilities to determine the ability of IMRT to deliver an optimal treatment plan.This includes calc...

The Therapeutic Potential of DNA Damage Repair Pathways and Genomic Stability in Lung Cancer

“…Dose fractionation and 3-Dimensional conformal radiation therapy (3DCRT, using CT images) significantly improved radiation treatment ( 146 ). The development of multileaf collimators allowing modulation of the X-ray beam dose-rate led to intensity-modulated radiation therapy (IMRT, characterized by a static delivery) and volumetric-modulated arc therapy (VMAT, with a dynamic delivery), which improved the target volume accuracy and led to less organ toxicity ( 147 , 148 ).…”

Challenges of radical chemoradiation planning in Stage III non-small-cell lung cancer: Can volumetric modulated arc radiotherapy overcome an unfavourable location?

“…18 F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) based treatment planning helps in this regard by both better tumour and nodal delineation, thus potentially sparing normal tissue. Multiple studies have shown dosimetric benefits of intensity modulated radiation therapy (IMRT) over 3-dimensional conformal radiotherapy (3D-CRT) but no overall survival benefit has been demonstrated [5][6][7][8][9].…”

Correlation of displacement of mediastinal metastatic lymph nodes with adjacent organs in non‐small cell lung cancer on four‐dimensional computed tomography

“…Ambiguous target due to tumor motion has been considered as one of the main reasons for local failure of tumor control . Several studies have shown that escalating radiation dose to the primary tumor might improve local control of the tumor . However, an increase in the radiation dose must be balanced against an increased risk of radiation toxicity.…”

“…2,3 Several studies have shown that escalating radiation dose to the primary tumor might improve local control of the tumor. [4][5][6][7] However, an increase in the radiation dose must be balanced against an increased risk of radi-This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. ation toxicity.…”