|Year : 2019 | Volume
| Issue : 2 | Page : 49-52
Radical brachytherapy for early-stage external auditory canal squamous cell carcinoma: A dosimetric feasibility study using plastic earbud as an applicator
Kanhu Charan Patro, PS Bhattacharyya, Sayan Paul, Chira Ranjan Khadanga, EB Rajmohon, Chitta Ranjan Kundu, Venkata Krishna Readdy P., Madhuri Palla, AC Prabu, Subhra Das, A Anil Kumar, Aketi Srinu, Susovan Banerjee, Sanjukta Padhi, Suman Das
Department of Radiation Oncology, Mahatama Gandhi Cancer Hospital, Visakhapatnam, Andhra Pradesh, India
|Date of Web Publication||30-Dec-2019|
Kanhu Charan Patro
Department of Radiation Oncology, Mahatama Gandhi Cancer Hospital, Visakhapatnam, Andhra Pradesh.
Source of Support: None, Conflict of Interest: None
Squamous cell carcinoma (SCC) of external auditory canal (EAC) is extremely rare. Although surgery followed by radio (chemo) therapy is the contemporary standard of care, radical radio (chemo) therapy has been successfully used as an anatomical as well as functional organ preservation modality. Radical brachytherapy is a promising alternative in early-stage SCC-EAC. We report our initial experience on the feasibility of using commercially available plastic earbud along with soft flexible earpiece of stethoscope as a radioactive source career applicator of remote after-loading high-dose rate radioactive sources (Ir192).
Keywords: Earpiece of stethoscope, external auditory canal, plastic earbud, squamous cell carcinoma
|How to cite this article:|
Patro KC, Bhattacharyya P S, Paul S, Khadanga CR, Rajmohon E B, Kundu CR, Readdy P. VK, Palla M, Prabu A C, Das S, Kumar A A, Srinu A, Banerjee S, Padhi S, Das S. Radical brachytherapy for early-stage external auditory canal squamous cell carcinoma: A dosimetric feasibility study using plastic earbud as an applicator. J Curr Oncol 2019;2:49-52
|How to cite this URL:|
Patro KC, Bhattacharyya P S, Paul S, Khadanga CR, Rajmohon E B, Kundu CR, Readdy P. VK, Palla M, Prabu A C, Das S, Kumar A A, Srinu A, Banerjee S, Padhi S, Das S. Radical brachytherapy for early-stage external auditory canal squamous cell carcinoma: A dosimetric feasibility study using plastic earbud as an applicator. J Curr Oncol [serial online] 2019 [cited 2020 Mar 28];2:49-52. Available from: http://www.journalofcurrentoncology.org/text.asp?2019/2/2/49/274303
| Introduction|| |
Squamous cell carcinoma (SCC) of external auditory canal (EAC) is extremely rare., Although the established current standard of care is radical surgery in early-stage tumors of EAC, radical radio (chemo) therapy has been attempted with an aim of both anatomical and functional organ preservation. Traditionally, radiotherapy (RT) has been delivered either using conventional wedge-pair portals or three-dimensional (3D) conformal techniques including intensity-modulated radiation therapy (IMRT). Recently, there is a growing interest in brachytherapy (BT) using remote after-loading high-dose rate (HDR) radioactive sources (Ir192), which has the advantage of delivering very high dose of radiation to the target volume with high conformity as well as precision with better sparing the surrounding critical structures. Radical surgery is debilitating and needs plastic reconstruction. Standard of care remains radical surgery with or without neck dissection and plastic reconstruction, but for certain group of patients with very early EAC lesion with deep infiltration and those who are medically inoperable, BT can be an alternative for lesions confined to cartilage or mucosa. Moreover, BT can be delivered in few fractions over fewer days in comparison with conventional fractionated RT. Considering all of these above, radical BT appears to be an attractive alternative to radical surgery especially in early-stage tumors of EAC with a comparable tumor-related local control along with much better acceptable cosmetic as well as functional outcome. Delivering BT requires a radioactive source placement within a unique applicator, which is generally placed within and/or close to the disease site. Here we report our initial experience on the feasibility of using commercially available plastic earbud as an applicator of remote after-loading HDR Ir192. We selected the plastic earbud as it is easily available everywhere as well as can be measured, calibrated, and connected to the source.
| Mono-institutional Initial Experience|| |
We selected the plastic earbud [Figure 1], which is commonly available in the market. It has an approximate length of 5 cm and inner diameter of 3 mm, whose dimensions are comparable with either the stainless steel needles [Figure 2] and [Figure 3] or nylon catheters available for remote-after-loading HDR Ir192. Plastic earbuds are atraumatic in nature in comparison with stainless steel needles. An interstitial one-end blind needle with a length of 10 cm is inserted into an earbud and the assembly is inserted into the EAC. The distal open end of the plastic earbud is sealed off by wax, so that the chance of penetrating needle injury is nullified in the case of needle movement during the procedure. The position of the plastic earbud in EAC can further be stabilized using an earpiece of stethoscope [Figure 4]. This combined arrangement of interstitial needle stethoscope earpiece along with the plastic earbud ensures proper reproducible positioning of the radioactive source during the dwell-time as well as patient comfort, hence making this arrangement as an effective radioactive source carrier prosthesis [Figure 5]. After obtaining an informed consent, we selected a volunteer for an initial feasibility study. Computed tomographic (CT) simulation scan of slice thickness of 1 mm with marked dummy radioactive wire inside the source carrier prosthesis of the temporal bone with 5 cm margin superoinferiorly. A plan was generated followed by initial dosimetric analysis using a treatment planning system (Oncentra, Elekta). A linear array of radioactive source position was activated for desired length and the plan was optimized. The dose was prescribed at 5 mm off-axis. If the gross tumor volume (GTV) is appreciated, a clinical target volume can be contoured with a margin of 1 cm around the GTV sparing the brain and tympanic membrane [Figure 6]. The high-dose sleeves in the surface of the applicator can be dampened by use of wax in the surface of the plastic earbud., , ,
|Figure 4: Ear bud and applicator attached and stethoscope piece connected |
Click here to view
| Discussion|| |
Tumors of EAC are rare and constitute 0.2% of all head and neck squamous cell carcinoma (HNSCC)., Of these the majority are SCC (85%). A tumor, node, metastasis staging system is most commonly followed, which includes histopathologic extent of tumor invasion and radiological evaluation. The contemporary treatment options include either radical surgery with or without postoperative adjuvant radio (chemo) therapy or radical radio (chemo) therapy depending upon the stage. Radical surgery followed by postoperative adjuvant radio (chemo) therapy is generally used in advanced disease.,,, Radical surgery includes wide excision of disease along with removal of middle and/or external ear results in poor cosmetic and functional outcomes. In contrast, radical RT that includes either external beam radiotherapy (EBRT), BT or sequentially combined can be an alternative with comparable local tumor control rate and acceptable cosmesis, especially in early-stage disease (without soft-tissue extension or bony erosion), although there is paucity of literatures to support this.,,, Although small-volume lesions can well be treated with BT alone, there are some technical challenges. Here, we attempt to deliver a radical BT dose using a unique source carrier prosthesis that consists of easily available plastic earbud stabilized with the earpiece of the stethoscope. It is a dosimetric feasibility study and we did not treat the patient (volunteer). He was comfortable throughout the procedure as well as physics-dosimetry to above arrangement was satisfactory. Our proposed dose schedule is like other SCC 3 Gy per fraction twice daily with 6-h gap and biological equivalent dose about more than 60 Gy over a period of 10 days. The actual dose is mostly for other SCC. There are no dose criteria for these organ-at-risk (OAR) structures such as tympanic membrane and cartilages. When we treat with external RT, we do not give constraints. As a principle, we should follow as low as reasonably achievable (ALARA) for these OAR structures. This is a feasibility study and in other literature late effects are not mentioned and reported. Stethoscope ear piece we taken as readymade. It can be performed also with wax, but it needs expertise to make it. The stability of this bud and catheter definitely earbud is more stable. Other things are earbud is cheaper and easily available.
| Conclusion|| |
The combination of commercially available plastic earbud along with soft flexible earpiece of stethoscope of a 10-cm 17-gauge interstitial needle can be a radioactive source carrier applicator prosthesis for radical BT of early-stage SCC-EAC. However, it requires further validations. It is an attempt to put a bit of innovation into practice for very early lesions of the EAC confine to the mucosa or cartilage away from the tympanic membrane for patients medically inoperable and reluctant for such debilitating surgery.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]