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Table of Contents
LETTER TO EDITOR
Year : 2019  |  Volume : 2  |  Issue : 1  |  Page : 33-36

Intracavitary brachytherapy can be a useful additive to simultaneous integrated boost with volumetric modulated arc therapy as dose escalation boost dose during primary irradiation for selected nasopharyngeal carcinoma cases


1 Department of Radiation Oncology, Yashoda Hospitals, Hyderabad, Telangana, India
2 Department of Radiation Oncology, Regional Cancer Centre, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India

Date of Web Publication26-Jun-2019

Correspondence Address:
Dr. Ashutosh Mukherji
Department of Radiation Oncology, Yashoda Hospitals, Raj Bhavan Road, Somajiguda, Hyderabad 500082, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JCO.JCO_19_18

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How to cite this article:
Mukherji A, Neelakandan V. Intracavitary brachytherapy can be a useful additive to simultaneous integrated boost with volumetric modulated arc therapy as dose escalation boost dose during primary irradiation for selected nasopharyngeal carcinoma cases. J Curr Oncol 2019;2:33-6

How to cite this URL:
Mukherji A, Neelakandan V. Intracavitary brachytherapy can be a useful additive to simultaneous integrated boost with volumetric modulated arc therapy as dose escalation boost dose during primary irradiation for selected nasopharyngeal carcinoma cases. J Curr Oncol [serial online] 2019 [cited 2019 Oct 18];2:33-6. Available from: http://www.journalofcurrentoncology.org/text.asp?2019/2/1/33/261470



Dear Editor

Locally persistent nasopharyngeal carcinoma (NPC) after radical chemoradiation is associated with an increased risk of local recurrence, and the extent of disease at the time of presentation is one of the single most important prognostic factors. Studies have reported poor rates of local control of approximately 40% in patients who have persistent local disease that is not addressed adequately and have a poorer survival rate compared to the patients achieving clinical or histologic remission.[1],[2] Also, patients with persistent or residual locoregional disease have an increased risk of distant metastasis.[3] More aggressive primary treatment to ensure better local control with less toxicity can be attempted with the incorporation of brachytherapy boost after external beam irradiation aiming to achieve doses in the range of 74–76 Gy locally.

Brachytherapy used as a boost has been studied extensively for dose escalation after 2 dimensional radiotherapy (2DRT), especially when there is no residual tumor.[4],[5],[6] This is because with 2DRT or even 3 dimensional conformal radiotherapy, dose escalation beyond 66 Gy was not possible without causing severe acute and late toxicities on surrounding soft tissues and skin.[4],[5],[6] Therefore, dose escalation beyond 66 Gy in nasopharynx by brachytherapy boost with intraluminal applicators or Intra-cavitary brachytherapy (ICBT) has been studied and found effective. But with the advent of intensity modulated radiotherapy (IMRT) and later volumetric modulated arc therapy (VMAT), localized area dose escalations and differential dose prescriptions became possible in the target volume with sparing of surrounding normal tissues. However, beyond 70–72 Gy, even these techniques have their limitations because of skin tolerances for entry doses, large area receiving significant dose, higher body integral dose, and the location of maximal dose points. Brachytherapy, on the contrary, limits the dose to the target volume only and the covering mucosa with a thin sleeve of tissue around the target volume getting significant doses (30%–50% of prescribed brachytherapy dose).

This pictorial essay describes a case of a 63-year-old man with stage T2N2M0 NPC presenting with a 1.5 × 1 × 1cm residual, localized superficial lesion over the left lateral wall of the nasopharynx at 1 week post-radical external beam concurrent chemoradiation delivered by VMAT technique to a dose of 70 Gy along with concurrent cisplatin given three times per week. The patient was due for post-radiotherapy maintenance chemotherapy; however, it was decided to deliver further boost dose of radiotherapy before starting chemotherapy as a planned dose escalation. The departmental protocol is to deliver the boost field after 50 Gy given to low-risk planning target volume (PTV) (low risk (LR)-PTV) as either a sequential boost up to 70 Gy or use simultaneous integrated boost (SIB) techniques with high-risk boost PTV (high risk (HR)-PTV) receiving 68.2 Gy in 31 fractions, intermediate-risk boost PTV (IR-PTV) receiving 62 Gy in 31 fractions, and LR-PTV receiving 55.8 Gy in 31 fractions. In this case, sequential boost had been given up to 70 Gy. Brachytherapy was chosen in view of initial superficial disease, age of patient, and to minimize dose to rest of mucosal tissue and surrounding critical organs. The local brachytherapy boost was delivered 1 week after completion of external beam radiotherapy with a Rotterdam applicator with three fractions each of 250 cGy over three consecutive days to a total dose of 750 cGy prescribed to 100% isodose line [Figure 1]. At 4 weeks after brachytherapy (during the course of maintenance chemotherapy), endoscopic assessment revealed no residual disease or necrotic areas. At 2 years after irradiation, no local or regional recurrences and no bone or soft tissue late effects were reported over the irradiated area. We aimed to present in this pictorial essay the procedure of the nasopharyngeal mold brachytherapy application and to compare the dose distribution observed in another case treated by external beam SIB-boost VMAT technique [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6].
Figure 1: (A) and (B) Three-dimensional (3D) reconstruction of applicator and target volume in treated area in patient

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Figure 2: (A) and (B) Dose wash of target volume with applicator in place

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Figure 3: Dose wash of target volume with external beam SIB-VMAT

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Figure 4: Dose wash of area receiving 30% of prescribed dose with external beam SIB-VMAT (A) and brachytherapy (B)

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Figure 5: Dose wash of area receiving 50% of prescribed dose with external beam SIB-VMAT (A) and brachytherapy (B)

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Figure 6: Quality assurance for brachytherapy dosimetry to verify the dwell positional accuracy of the stepping source

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Brachytherapy applications of the nasopharynx are restricted as boost minimal residual local disease after external irradiation or as salvage therapy for well-circumscribed and superficial local recurrences limited to the nasopharyngeal cavity without the involvement of the underlying bone or extending to oropharynx or nasal cavities.[6],[7] Thus, this technique can be applied only in cases with limited superficial mucosal disease remaining after external beam radiotherapy or after complete resolution (for mucosal dosing). It cannot be used for deeply infiltrating tumors or other T4 disease.[8],[9] The dose is usually prescribed to an isodose covering the surface of the underlying bone, which is situated at 5–10mm from the mucosal surface. Dose distribution is optimized when possible so that the reference isodose follows the bone surface. The schedule chosen for this patient is based on the study by Levendag et al.,[10] in which a dose of 3 Gy per fraction was delivered after a rest period of 1–2 weeks as a boost to the primary site with high-dose-rate brachytherapy. T1–T3 tumors received six fractions after 60 Gy external beam irradiation and T4 tumors received four fractions after 70 Gy external beam irradiation.

In a similar paper from Taiwan, Chao et al.[11] have argued for the benefit of introducing an intracavitary brachytherapy boost as a planned intervention even in cases treated by IMRT. They reported on outcomes in a cohort of 230 patients over 10 years, of whom 124 had received 6 Gy in two fractions planned boost after IMRT 70 Gy. The mean follow-up time was 63.1 months. The 5-year overall survival and local control rates were 81.5% and 91.5%, respectively. In a subgroup analysis, 75 T1 patients with ICBT boost had significantly better local control than T1 patients without ICBT boost (98.1% vs. 85.9%; P = 0.020) and this benefit was independent of concurrent chemotherapy. Multivariate analysis showed that both ICBT (P = 0.029) and chemotherapy (P = 0.047) influenced local control for T1 patients.[11] A recent International Atomic Energy Agency (IAEA) paper has however reported no benefit of dose escalation with ICBT but in this paper, the radiotherapy was given by 2DRT, and hence the survival rates were comparable with earlier studies.[12] Also, the reported sequelae from the study by Chao et al.[11] had lower rates of cranial nerve palsy (5.6%), Lhermitte’s sign (7.3%), or osteoradionecrosis (0%) than that reported in previous literature (10%–20%).[11] In our treated case also, after more than 2 years, no long-term sequelae were reported. Thus, the authors argue for a consideration for routine use of planned brachytherapy after external beam radiotherapy for local dose escalation after 70 Gy in selected cases with superficial mucosal disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Sze WM, Lee AW, Yau TK, Yeung RM, Lau KY, Leung SK, et alThe prognostic value of endoscopic findings after radical radiotherapy for nasopharyngeal carcinoma. Proceedings of the UICC Workshop on Nasopharyngeal Cancer. Singapore: Armour Publishing PTE; 1998. pp. 239.  Back to cited text no. 1
    
2.
Kwong DL, Nicholls J, Wei WI, Chua DT, Sham JS, Yuen PW, et al. The time course of histologic remission after treatment of patients with nasopharyngeal carcinoma. Cancer 1999;85:1446-53.  Back to cited text no. 2
    
3.
Kwong D, Sham J, Choy D. The effect of loco-regional control on distant metastatic dissemination in carcinoma of the nasopharynx: An analysis of 1301 patients. Int J Radiat Oncol Biol Phys 1994;30:1029-36.  Back to cited text no. 3
    
4.
Levendag PC, Lagerwaard FJ, Noever I, dePan C, vanNimwegen A, Wijers O, et al. Role of endocavitary brachytherapy with or without chemotherapy in cancer of the nasopharynx. Int J Radiat Oncol Biol Phys 2002;52:755-68.  Back to cited text no. 4
    
5.
Lee N, Hoffman R, Phillips TL, Xia P, Quivey JM, Weinberg V, et al. Managing nasopharyngeal carcinoma with intracavitary brachytherapy: One institution’s 45-year experience. Brachytherapy 2002;1:74-82.  Back to cited text no. 5
    
6.
Chang JT, See LC, Tang SG, Lee SP, Wang CC, Hong JH. The role of brachytherapy in early-stage nasopharyngeal carcinoma. Int J Radiat Oncol Biol Phys 1996;36:1019-24.  Back to cited text no. 6
    
7.
Chassagne D, Janvier L, Pierquin B, Flaisler A. [Curie-like therapy of cancers of the cavum with plastic tubing and iridium-192]. Ann Radiol (Paris) 1963;6:719-26.  Back to cited text no. 7
    
8.
Leung TW, Wong VY, Sze WK, Lui CM, Tung SY. High-dose-rate intracavitary brachytherapy boost for early T stage nasopharyngeal carcinoma {private}. Int J Radiat Oncol Biol Phys 2008;70:361-7.  Back to cited text no. 8
    
9.
Levendag PC, Keskin-Cambay F, de Pan C, Idzes M, Wildeman MA, Noever I, et al. Local control in advanced cancer of the nasopharynx: Is a boost dose by endocavitary brachytherapy of prognostic significance? Brachytherapy 2013;12:84-9.  Back to cited text no. 9
    
10.
Levendag PC, Peters R, Meeuwis CA, Visch LL, Sipkema D, de Pan C, et al. A new applicator design for endocavitary brachytherapy of cancer in the nasopharynx. Radiother Oncol 1997;45:95-8.  Back to cited text no. 10
    
11.
Chao HL, Liu SC, Tsao CC, Lin KT, Lee SP, Lo CH, et al. Dose escalation via brachytherapy boost for nasopharyngeal carcinoma in the era of intensity modulated radiation therapy and combined chemotherapy. J Radiat Res 2017;58:654-60.  Back to cited text no. 11
    
12.
Rosenblatt E, Abdel-Wahab M, El-Gantiry M, Elattar I, Bourque JM, Afiane M, et al. Brachytherapy boost in loco-regionally advanced nasopharyngeal carcinoma: A prospective randomized trial of the international atomic energy agency. Radiat Oncol 2014;9:67.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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