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Table of Contents
LETTER TO EDITOR
Year : 2020  |  Volume : 3  |  Issue : 2  |  Page : 414-415

Differentiating radiation necrosis vis-à -vis recurrence in brain metastasis


Department of Radiation Oncology, Apollo Proton Cancer Centre, Chennai, Tamil Nadu, India

Date of Submission05-Mar-2020
Date of Decision05-Mar-2020
Date of Acceptance05-Mar-2020
Date of Web Publication19-Jun-2020

Correspondence Address:
Rakesh Jalali
Department of Radiation Oncology, Apollo Proton Cancer Centre, Chennai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/CRST.CRST_68_20

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How to cite this article:
Gaikwad U, Jalali R. Differentiating radiation necrosis vis-à -vis recurrence in brain metastasis. Cancer Res Stat Treat 2020;3:414-5

How to cite this URL:
Gaikwad U, Jalali R. Differentiating radiation necrosis vis-à -vis recurrence in brain metastasis. Cancer Res Stat Treat [serial online] 2020 [cited 2020 Aug 7];3:414-5. Available from: http://www.crstonline.com/text.asp?2020/3/2/414/287260



With improvement in systemic chemotherapy, targeted therapy, the increasing role of immunotherapy, relatively lower threshold of imaging and availability of modern diagnostic modalities, the incidence of brain metastasis is increasing. High-precision radiation therapy techniques of stereotactic radiosurgery and fractionated radiotherapy with or without systemic agents have improved the survival and patient-reported outcomes in these patients, as well. Recursive partition analysis score and diagnosis-specific graded prognostic assessment score are frequently used in clinical practice to prognosticate and help define the most appropriate treatment strategies for these patients.[1] Whole-brain radiotherapy (WBRT) is generally indicated in patients with multiple metastases, large metastases (>4 cm), poorly controlled systemic disease, and in low-performance status patients. Advances in radiotherapy techniques such as hippocampal-sparing WBRT have shown significant benefit in preserving cognitive functions and quality of life in these patients.[2]

Postradiation changes can be acute, subacute, and late, which can be caused by vascular changes, glial changes, and damage to the blood-brain barrier causing edema, mass effects, etc. Postradiation changes may mimic disease progression and this is termed as pseudo-progression, typically observed in the first few months after treatment. Patients can sometimes also develop frank radiation-induced necrosis (RIN), which can be seen as late as 18–24 months postradiotherapy. Prior or concurrent systemic therapies (chemotherapy, targeted therapy, and immunotherapy) increase the risk of RIN. Postradiotherapy changes and RIN are often difficult to distinguish from true tumor progression and present a clinical challenge. The case in this issue exemplified this diagnostic dilemma of RIN versus tumor progression.[3] Multiparametric magnetic resonance imaging (MRI) brain with perfusion assay and magnetic resonance spectroscopy (MRS) are helpful in differentiating radiation changes from disease recurrence. Currently, modified Response Assessment in Neuro-Oncology (RANO) criteria using various MRI features along with clinical assessment have been advocated to be used to help establish the correct diagnosis. Diffusion-weighted imaging with higher apparent diffusion coefficient (ADC) values, extensive lipid lactate peak on MRS and decreased relative cerebral blood volume values on perfusion scans favor the diagnosis of RIN, but both RIN and a recurrent lesion can show neuronal loss (low NAA), and abnormal cellular membrane attenuation (high choline).[4] It is important to correlate all MRI findings with clinical signs and symptoms and also to assess the clinico-radiological features in chronological order. In the present case, the MRI features and clinical presentation were in favor of RIN.

Fluorodeoxyglucose positron-emission tomography-computed tomography, particularly with newer radiotracers is another option for RIN diagnosis, but low sensitivity and sensitivity with limited data, have precluded its routine use.[5] In symptomatic patients with the empirical diagnosis of RIN, corticosteroids may be used with or without other measures such as medical decompression therapy, anti-angiogenic agents, and checkpoint inhibitors with surgical resection reserved for refractory cases.

It is important to rule out the diagnosis of RIN in brain metastases patients postradiotherapy with or without systemic therapy. With the help of modern imaging modalities, timely diagnosis and management of RIN will improve patient-related outcomes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Gaspar L, Scott C, Rotman M, Asbell S, Phillips T, Wasserman T, et al. Recursive partitioning analysis (RPA) of prognostic factors in three Radiation Therapy Oncology Group (RTOG) brain metastases trials. Int J Radiat Oncol Biol Phys 1997;37:745-51.  Back to cited text no. 1
    
2.
Andrews DW, Scott CB, Sperduto PW, Flanders AE, Gaspar LE, Schell MC, et al. Whole brain radiation therapy with or without stereotactic radiosurgery boost for patients with one to three brain metastases: Phase III results of the RTOG 9508 randomised trial. Lancet 2004;363:1665-72.  Back to cited text no. 2
    
3.
Madala RK, Krishnatry R, Noronha V, Patil V, Joshi A, Menon N, et al. Neurological deterioration in a patient with lung cancer and brain metastasis. Cancer Res Stat Treat 2020;3:97-9.  Back to cited text no. 3
  [Full text]  
4.
Sundgren PC. MR spectroscopy in radiation injury. AJNR Am J Neuroradiol 2009;30:1469-76.  Back to cited text no. 4
    
5.
Ricci PE, Karis JP, Heiserman JE, Fram EK, Bice AN, Drayer BP. Differentiating recurrent tumor from radiation necrosis: Time for re-evaluation of positron emission tomography? AJNR Am J Neuroradiol 1998;19:407-13.  Back to cited text no. 5
    




 

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