|LETTER TO THE EDITOR
|Year : 2021 | Volume
| Issue : 4 | Page : 773-774
Precision radiotherapy in carcinoma esophagus: Does conformity translate into significant clinical outcomes?
Sambit Swarup Nanda, Ashutosh Mukherji, Satyajit Pradhan
Department of Radiation Oncology, Mahamana Pandit Madan Mohan Malaviya Cancer Centre, Homi Bhabha Cancer Hospital, Varanasi, Uttar Pradesh, India
|Date of Submission||28-Oct-2021|
|Date of Decision||01-Nov-2021|
|Date of Acceptance||25-Nov-2021|
|Date of Web Publication||29-Dec-2021|
Sambit Swarup Nanda
Department of Radiation Oncology, Mahamana Pandit Madan Mohan Malaviya Cancer Centre, Homi Bhabha Cancer Hospital, Varanasi, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Nanda SS, Mukherji A, Pradhan S. Precision radiotherapy in carcinoma esophagus: Does conformity translate into significant clinical outcomes?. Cancer Res Stat Treat 2021;4:773-4
|How to cite this URL:|
Nanda SS, Mukherji A, Pradhan S. Precision radiotherapy in carcinoma esophagus: Does conformity translate into significant clinical outcomes?. Cancer Res Stat Treat [serial online] 2021 [cited 2022 Jan 28];4:773-4. Available from: https://www.crstonline.com/text.asp?2021/4/4/773/334190
Radiotherapy (RT) for esophageal carcinoma has been challenging, given its proximity to delicate organs at risk (OARs) such as the spinal cord, heart, and lungs. This has led to the evolution of advanced techniques like volumetric-modulated arc therapy (VMAT) for achieving better conformity to target volumes and limiting the doses to critical OARs. However, whether the theoretical and/or dosimetric advantage of the VMAT technique over three-dimensional conformal RT (3D-CRT) can be translated to actual clinically significant outcomes remains debatable.
A recent study by Dora et al., has focused on this pertinent question. The authors must be complimented for conducting a detailed retrospective analysis of the patients with carcinoma esophagus being treated by either technique. The greatest strength of the study lies in the univariate and multivariate analyses of all the endoscopic, radiological, clinical as well as dosimetric variables and their correlation with outcomes in both groups. However, there are some points that need to be pondered upon for the better understanding of the readers.
The use of functional imaging like positron emission tomography-computed tomography (PET-CT) scan has shown upstaging in about 30% of the cases compared to conventional imaging and has been recommended for the purpose of staging as well as assessing the response to therapy. An insight into whether PET-CT was performed and if so, when, will be quite useful for the readers in light of the recent evidence.
There was significant heterogeneity in the total dose delivered to the target volume ranging from 50.4–63 Gy. Previous attempts in a large randomized controlled trial (RCT) setting for dose escalation have failed to demonstrate a survival benefit, but definitely increased the toxicities. However, these results need to be revisited with the use of modern RT techniques like VMAT. Thus, it will be useful for authors to explain the dose variation in terms of the location of the tumor, if there was any, and whether the dose delivery was limited or facilitated by the RT technique being used. The authors must be commended for explaining the RT target volumes and techniques in detail, however, there are two points that need clarification. While using phased plans, either 3D-CRT or 3D-CRT followed by VMAT boost, it needs to be explained whether the boost target volume was the same as the initial PTV. In addition, an explanation of whether any customized shield was used in the cobalt setting for limiting the dose to the lung needs to be provided for better understanding of the readers.
The study by Dora et al. showed a significant reduction in the mean heart dose, V25, and V30 with the VMAT plans compared to the conformal plans. A subgroup analysis of these cardiac parameters with respect to the location of the tumor could shed further light on the extent of benefit in terms of cardiac sparing in different clinical scenarios.
Another pertinent point to ponder upon remains the concurrent chemotherapeutic regimen. Most phase III RCTs, have used cisplatin and 5-fluorouracil (5-FU) as opposed to paclitaxel and carboplatin used in this study as the concurrent regimen. The authors need to discuss the implications of this in terms of acute pharyngoesophagitis, which is not only dependent on the RT technique but also on the target volume and concurrent chemotherapeutic agent. Acute grade II and III pharyngoesophagitis was seen in 28.1% versus 17.6% and 4.7% versus 2.0% patients in the VMAT versus conformal RT groups, respectively. This is broadly in line with the meta-analysis data of about 25% grade II and III acute radiation esophagitis. A comparative analysis of this clinically significant toxicity with large RCT data that used concurrent cisplatin and 5-FU would be very useful.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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