|Year : 2016 | Volume
| Issue : 1 | Page : 314-317
A pilot study to evaluate the efficacy of cerrobend shielding stents in preventing adverse radiotherapeutic effects in buccal carcinoma patients
Karma Yangchen1, Ramashanker Siddharth1, Saumyendra V Singh1, Raghuwar D Singh1, Himanshi Aggarwal1, Niraj Mishra1, Shuchi Tripathi1, Kirti Srivastava2, Teethraj Verma2, Pradeep Kumar1
1 Department of Prosthodontics, Faculty of Dental Sciences, King George's Medical University UP, Uttar Pradesh, India
2 Department of Radiotherapy, King George's Medical University UP, Lucknow,
Uttar Pradesh, India
|Date of Web Publication||13-Apr-2016|
Saumyendra V Singh
2/273, Viram Khand, Gomti Nagar, Lucknow - 226 010, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Background: Radiation stents made of Lipowitz metal or cerrobend alloy are commonly used to shield uninvolved tissues from electron beams used in therapeutic radiation treatment of head and neck cancers. However, studies investigating the efficacy of cerrobend shielding stent in patients with unilateral buccal carcinoma remain rare.
Purpose: To evaluate the efficacy of cerrobend shielding stents in minimizing the potential adverse effects of radiation on oral tissues in buccal carcinoma patients.
Materials and Methods: Twenty.eight participants were selected for the study based on predetermined inclusion criteria, out of which four participants were lost to follow-.up. Half of the remaining participants. (N = 12) were randomly given cerrobend shielding stent and the remaining 12 formed the control group. The effects of radiotherapy were evaluated by using Radiation Therapy Oncology Group. (RTOG) 0435 Head and Neck adverse effects grading tool. All participants were evaluated for xerostomia, mucositis, dysphagia, salivary changes, dysguesia, pain, trismus and radiation caries at baseline and 1 and 3. months post.radiotherapy.
Results: All adverse effects were higher in control compared to study group, with post therapy difference for pain in swallowing, salivary changes, mucositis, dysphagia, dry mouth and caries being statistically significant.
Conclusions: Cerrobend alloy can be used effectively as shielding stent to reduce the adverse effects associated with external beam radiation therapy in unilateral buccal carcinoma patients.
Keywords: Oral cancer, radiation therapy, stent
|How to cite this article:|
Yangchen K, Siddharth R, Singh SV, Singh RD, Aggarwal H, Mishra N, Tripathi S, Srivastava K, Verma T, Kumar P. A pilot study to evaluate the efficacy of cerrobend shielding stents in preventing adverse radiotherapeutic effects in buccal carcinoma patients. J Can Res Ther 2016;12:314-7
|How to cite this URL:|
Yangchen K, Siddharth R, Singh SV, Singh RD, Aggarwal H, Mishra N, Tripathi S, Srivastava K, Verma T, Kumar P. A pilot study to evaluate the efficacy of cerrobend shielding stents in preventing adverse radiotherapeutic effects in buccal carcinoma patients. J Can Res Ther [serial online] 2016 [cited 2021 Jan 16];12:314-7. Available from: https://www.cancerjournal.net/text.asp?2016/12/1/314/154015
| > Introduction|| |
Radiation therapy is an extremely effective treatment for buccal carcinoma, both as a primary modality and as an adjuvant treatment following surgery. Although intensity-modulated radiotherapy (IMRT) allows sparing of normal tissue while delivering radical radiation doses to the target volumes, yet in most of the developing countries, external beam radiation therapy (EBRT) is still the most commonly used technique of radiotherapy, due to cost effectiveness. But, it is associated with various adverse effects such as xerostomia, mucositis, dysphagia, salivary changes, dysguesia, pain, trismus and radiation caries etc. Protecting normal tissues from radiation injury is as important as it is to target diseased tissues with radiation as the success of radiotherapy is often limited by sequelae to the surrounding tissues outside the treatment field. Radiation stents may be constructed to protect healthy tissues from adverse effects of treatment and to concentrate radiation in region of the tumor mass., Lipowitz metal or cerrobend alloy is commonly used to shield uninvolved tissues from electron beams used in therapeutic radiation treatment of head and neck cancers. Buccal carcinoma is one of the most common malignant neoplasms among all oral cancers in India and neighboring countries because of tobacco and betel nut chewing.
However, studies investigating the efficacy of cerrobend shielding stent in patients with unilateral buccal carcinoma remain rare. So, the present pilot study evaluated the efficacy of cerrobend (50% bismuth, 26.7% lead, 13.3% tin and 10% cadmium) shielding stents in minimizing the potential harmful effects of radiation on oral tissues in patients of buccal carcinoma.
| > Materials and Methods|| |
Twenty-eight participants scheduled for radiotherapy post-surgically for unilateral buccal carcinoma who satisfied the inclusion criteria of adequate mouth opening, a stage III lesion with no distant metastasis, no contralateral, deep neck nodal involvement or contralateral disease extensions (as confirmed by Contrast Enhanced Computed Tomographic scanning) according to TNM classification of the Union for International Cancer Control- American Joint Commission or Cancer Staging and End Resulting Reporting (UICC-AJCC) were selected for the study after ethics committee approval and obtaining informed consent.
Sample size determination was not possible as this was a pilot, first of its kind study with scanty existing literature. No estimates were available in literature for proposed study to provide basis for power analysis for determination of sample size. So, patients satisfying the inclusion criteria during study duration (18 months) were included. Using randomization software, the sample was divided into study group (N = 14) that was given cerrobend shielding stent during radiotherapy and a control group that received radiotherapy without shielding stent. The stent was fabricated by using an interocclusal record of aluwax (Aluwax; AluwaxDental Products Co.) at maximum comfortable mouth opening of the patient. After articulation on a semi adjustable articulator, a 2 mm thickness of baseplate wax (Modelling wax; MaarcGoregoan) was adapted on the occlusal surface of the teeth on the unaffected side of the maxillary cast extending to the mid-palatine raphe and up to the facial sulcus of the unaffected maxilla till the midline. A similar baseplate was adapted on the occlusal surface of the mandibular unaffected half up to the alveolo-lingual sulcus and facial sulcus till the midline. Occlusal rims were then fabricated on these baseplate at the height decided by interocclusal record. It was ensured that the combined facio-lingual thickness of wax was at least 10 mm at maximum comfortable mouth opening of the patient to protect the unaffected oral tissues from adverse effects during radiotherapy. The maxillary and mandibular rims were invested separately, dewaxed, followed by casting with cerrobend alloy and fitted into each other with the help of indexing notches [Figure 1]. All participants were given common oral hygiene instructions and symptomatic treatment for any radiotherapy adverse effects.
All the participants were given conventional external radiotherapy (Theratron 780E, MDS Nordion) in two phases over 6 weeks. The first phase (46 Gy dose in 23 fractions, 5 fractions/week) was administered by single lateral field by skin surface dose (SSD) technique; the second phase consisted of 14 Gy dose in seven fractions in reduced field after sparing the spinal cord. The efficacy of cerrobend shielding stents was evaluated by comparing the groups in terms of adverse effects induced by radiotherapy. Radiation side effects were graded by using Radiation Therapy Oncology Group (RTOG) 0435 Head and Neck adverse effects grading tool from the National Cancer Institute's Common Terminology Criteria for Adverse Effects (CTCAE). All participants were evaluated for xerostomia, mucositis, dysphagia, salivary volume changes, dysguesia, pain, trismus and radiation caries at baseline (prior to radiotherapy) and 1 and 3 months post-radiotherapy. Four participants were lost to follow-up (two in each group), so they were excluded from the study. Data obtained from remaining 24 participants was analyzed statistically with STATISTICA statistical software (Windows version 6.0). The Mann-Whitney U test was used for statistical analysis of the ordinal data to derive 'z” score, with P value of less than.05 indicating statistical significance.
| > Results|| |
In the present study, loss to follow-up was around 14%. There was no significant difference for any of the parameters between study group and control group at baseline [Table 1]. However, 1 month post-radiotherapy, statistically significant differences (P < 0.05) were seen in pain on swallowing, salivary changes, mucositis, dysphagia and dry mouth between the groups as shown in [Table 2]. The severity of trismus, caries and taste alteration increased for both in groups following 1 month after radiotherapy; however the difference was not significant.
At 3 months post-radiotherapy, all adverse effects were higher in the control group as compared to study group, with statistically significant differences for pain in swallowing, salivary changes, mucositis, dysphagia, dry mouth and caries as illustrated in [Table 3].
| > Discussion|| |
IMRT is an advanced approach to 3-D treatment planning and conformal therapy and has mostly replaced EBRT in developed countries, but due to being expensive, is still used less in low resource setting such as India. But EBRT is associated with a number of adverse effects. To minimize these, radiation stents can be used. The available literature is scarce on efficacy of these stents. Hence this study was planned to evaluate the usefulness of stents in minimizing adverse effects associated with EBRT of buccal carcinoma.
In the present study, Cerrobend was used to fabricate the stents as it is a low fusing alloy which can be easily cast into desired form without the need of extensive armamentarium and 1 cm thickness of alloy can absorb up to 95% of 18 MeV. 2.
Due to stringent selection criteria and short duration of this study, only 28 participants could be included. Eighty six percent of the participants were followed-up throughout the duration of the study. RTOG Head and Neck adverse effects grading tool has been used in previous studies8 and was found to be effective in analyzing radiation associated adverse effects. There was no significant difference in any adverse effect prior to radiotherapy, indicating minimization of confounding factors and matching study and control groups except for the difference of one variable that is cerrobend stent.
The significantly lower occurrence of pain on swallowing, mucositis, salivary changes, dysphagia and dry mouth, 1 and 3 months post-radiotherapy in the study compared to the control group, could be probably due to shielding effect offered by cerrobend stent. The statistically significantly increased caries incidence in the control group at 3 months post-radiotherapy may be due to trismus, mucositis (diminished hygiene maintenance) and xerostomia with changes in salivary consistency (increased bacterial growth), thus forming a favorable niche for cariogenic organisms in the presence of compromised oral hygiene measures. There was no significant difference between the groups, for taste alteration and trismus from baseline to 1 and 3 months post radiotherapy, probably owing to short duration of study.
Due to small sample size, power of the present study would be low. The effect of the shield in minimizing adverse effects on the unaffected side was analysed as the stent covered only this side intraorally. No attempt was therefore made to assess its effect on the ipsilateral local site or opposite nodal stations. Future long duration research with larger patient cohort, analyzing effect of the shield on dose distribution at multiple sites as well as use of techniques such as computer-aided designing/computer aided manufacturing (CAD/CAM) and rapid prototyping technologies in stent fabrication, could strengthen routine use of cerrobend shielding stent in minimizing adverse effects in buccal carcinoma patients undergoing external beam radiotherapy. This study was the first of its kind and yielded significant results for developing countries such as India.
| > Conclusion|| |
Within the limitations of this study, following conclusion were drawn-
- Cerrobend alloy can be used effectively as shielding stent to reduce the adverse effects of radiation therapy in unilateral buccal carcinoma patients
- The pain on swallowing, salivary changes, xerostomia, mucositis and dysphagia were statistically significantly (P < 0.05) lower in the study group as compared to the control group
- The caries incidence was statistically significantly (P < 0.05) lower in the study group as compared to the control group at 3 months post-radiotherapy
- The study however, remained inconclusive with regard to trismus and taste alteration, probably due to shorter duration of the study.
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[Table 1], [Table 2], [Table 3]