IMRT and IGRT in head and neck cancer: Have we delivered what we promised?

Abstract

Intensity-modulated radiation therapy (IMRT) is a revolutionary new paradigm that aims at improving the therapeutic ratio by increasing the dosegradient between target tissues and surrounding normal structures thereby offering probability of better loco-regional control with decreased risk of complications. IMRT is relatively intolerant to set-up uncertainties, warranting periodic image-guidance, making Image-Guided Radiation Therapy (IGRT) a natural corollary to IMRT. There are several challenges associated with the planning, delivery, and quality assurance of the IMRT and IGRT processes that must be addressed to realize the full potential of such exciting and promising technology. Given the complexities involved, it is quite intuitive to understand that IMRT and IGRT are resource-intensive, demanding increased labor, rigour, and expenses too. Other disadvantages associated with high-precision techniques include potentially increased risk of marginal failures, decreased dose homogeneity, and an increase in total body dose with increased risk of secondary carcinogenesis. The aim of this review is to define the role of IMRT and IGRT in contemporary head and neck oncologic practice through a critical appraisal of pertinent literature. Despite relatively short follow-up and limited clinical outcomes data, the weight of evidence suggests that loco-regional control is not inferior (either comparable or even better) and toxicity lesser with IMRT resulting in potentially improved quality-oflife, prompting the widespread adoption of such technology in community practice. Ongoing clinical trials in head and neck IMRT are currently addressing issues to optimize the IMRT process, adopting functional imaging for dose-painting, and incorporating adaptive re-planning strategies to further improve outcomes.

Prospective randomized controlled trial to compare 3‐dimensional conformal radiotherapy to intensity‐modulated radiotherapy in head and neck squamous cell carcinoma: Long‐term results

“…Hence, it is important to improve the delivery of both chemotherapy and radiotherapy (RT) to minimize the sequelae of treatment. The delivery of RT to the head and neck region has seen dramatic changes over the last 2 decades from conventional radiotherapy through 3D conformal RT to intensity‐modulated radiotherapy (IMRT), the primary objective being better protection of critical normal organs without compromising control rates . Although conventional RT has the ability to irradiate the target volumes to high doses, it results in higher radiation sequelae.…”

“…The delivery of RT to the head and neck region has seen dramatic changes over the last 2 decades from conventional radiotherapy through 3D conformal RT to intensity-modulated radiotherapy (IMRT), the primary objective being better protection of critical normal organs without compromising control rates. 3 Although conventional RT has the ability to irradiate the target volumes to high doses, it results in higher radiation sequelae. The availability of multileaf collimators allows better beam shaping with better conformality to the target volumes and higher sparing of the organs at risk.…”

Reduced toxicity with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy compared with conventional two-dimensional radiotherapy for esophageal squamous cell carcinoma: a secondary analysis of data from four prospective clinical

“…23,24 Promising techniques are focused on the following areas: (i) biological imaging for better definition of the tumor volume; (ii) four-dimensional (4D) imaging for modeling the intra-fraction organ motion; (iii) an on-board imaging system or imaging devices registered to the treatment machines for inter-fraction patient localization; and (iv) treatment planning and delivery schemes incorporating the information derived from the new imaging techniques. 23,24 Promising techniques are focused on the following areas: (i) biological imaging for better definition of the tumor volume; (ii) four-dimensional (4D) imaging for modeling the intra-fraction organ motion; (iii) an on-board imaging system or imaging devices registered to the treatment machines for inter-fraction patient localization; and (iv) treatment planning and delivery schemes incorporating the information derived from the new imaging techniques.…”

“…The results of the current study provide further motivation to investigate the benefits of even more advanced RT technologies, such as IGRT, which has now been shown in both retrospective and prospective data to improve complications. 23,24 Promising techniques are focused on the following areas: (i) biological imaging for better definition of the tumor volume; (ii) four-dimensional (4D) imaging for modeling the intra-fraction organ motion; (iii) an on-board imaging system or imaging devices registered to the treatment machines for inter-fraction patient localization; and (iv) treatment planning and delivery schemes incorporating the information derived from the new imaging techniques. 25 Compared with 3DCRT/IMRT, the advanced technique can further reduce positioning error, maximally improve the tumor control probability (TCP) and reduce the normal tissue complication probability (NTCP).…”

Revolusi Teknik Radioterapi pada Karsinoma Nasofaring

“…(b) 3DCRT, dan (c) IMRT pada pasien KNF. Tampak peningkatan konformitas pada volume target dan sparirng jaringan normal di sekitarnya Sumber: rujukan no 37. Studi yang dilakukan Lee dkk 18 terhadap 1593 pasien KNF menunjukkan bahwa peningkatan kesintasan dan reduksi toksisitas yang serius dapat dicapai seiring revolusi teknik radiasi dari era 2DRT ke 3DRT hingga IMRT 18.…”