|Year : 2021 | Volume
| Issue : 1 | Page : 19-22
An institutional experience of early glottic cancers treated with radiotherapy
Aastha Shah, U Suryanarayan
Department of Radiotherapy, GCRI, Ahmedabad, Gujarat, India
|Date of Submission||25-Dec-2020|
|Date of Acceptance||01-Jan-2021|
|Date of Web Publication||25-Mar-2021|
Dr. Aastha Shah
Department of Radiotherapy, GCRI, Ahmedabad, Gujarat
Source of Support: None, Conflict of Interest: None
Introduction: This retrospective study aimed at analyzing the recurrence rates in early glottic cancers (tumor, node, metastasis Stages I and II) treated at Gujarat Cancer and Research Institute (GCRI) from 2014 to 2018 by radiotherapy alone. Materials and Methods: The present study included 170 patients treated at GCRI from January 2014 to December 2018. One hundred and twenty-six patients were of stage T1N0, and rest 44 were of T2N0. Total radiotherapy dose received by them were 60 Gray in 30 fractions on linear accelerator with 6 MV photons without elective neck irradiation. Results: The mean duration of follow-up was 60 months. The local control (LC) rate was 93.65% in stage T1N0 stage and 84.1% in stage T2N0 glottic cancer. Out of the total 170 patients included in this study, 15 patients developed local recurrence which was biopsy proven, leading to overall local failure rate of 8.82%, and the mean time to recurrence as noted in our study was 9.1 months. Ultimate LC rate by radiotherapy alone was 91.2%. Conclusion: Radiotherapy provides better LC along with the advantage of organ preservation in T1N0 and T2N0 glottic cancer, and the local failure can be salvaged by surgery.
Keywords: Early stage, glottic cancer, hypofractionation, institution experience, radiation, surgical salvage
|How to cite this article:|
Shah A, Suryanarayan U. An institutional experience of early glottic cancers treated with radiotherapy. J Radiat Cancer Res 2021;12:19-22
| Introduction|| |
Glottis is the pivot of voice. It is responsible for speech as well as swallowing and airway protection. Cancers of the larynx represent 2% of the total cancer burden and accounts 0.3% of all cancer deaths. It is the second most common head and neck cancer. The ratio of glottic to supraglottic cancer is approximately 2:1., Most lesions of the vocal cord begin on the upper surface and free margin of the true vocal cord. The anterior part involvement is the most common. There are no capillary lymphatics of true vocal cords. The incidence of clinically positive lymph nodes in T1 pure glottis cancer approaches zero and for T2 lesion is <2%.The ultimate goal of treatment is locoregional control and voice preservation. Early glottic cancers can be treated by surgery (cordectomy), laser excision, or radiotherapy. The primary goal of any of these treatment approaches is at achieving better local control (LC). Recurrence after these treatments is usually treated by surgery like partial or total laryngectomy. Chemotherapy can be an option for those who refuse surgery. This retrospective study aimed at analyzing the pattern of recurrence in Stage I and II pure glottic cancers treated at our institution, Gujarat Cancer and Research Institute (GCRI) from 2014 to 2018 by purely radiotherapy.
| Materials and Methods|| |
This retrospective study was conducted after obtaining Institutional Ethical Clearance. The case files of all patients registered at our institute from the year 2014 to 2018 with the histological diagnosis of carcinoma larynx were acquired from the medical records and from them, the patients with early glottic cancer, to be precise Stage I and II were reviewed and their radiation charts were retrieved from our department and assessed and thereafter the present status of the patients were acquired. Patients included in the study were all those who had histologically proven squamous cell carcinoma of vocal cord, tumor, node, metastasis Stage I (T1N0) (disease confined to (a) one or (b) both vocal cords) and II (T2N0) (extends to supraglottis or subglottis and/or impaired vocal cord mobility) as per the American Joint Cancer Committee eighth edition. All patients treated with single modality of radiotherapy in GCRI from the years 2014 to 2018 were included in the study. Both genders and all age groups were included in the study. Patients treated previously with cordectomy or partial laryngectomy, histology other than squamous cell carcinoma, and recurrent cases were excluded from the study. The total number of patients included in the study was 170. The diagnostic workup included the evaluation of performance status, complete blood counts, Chest X-ray, computed tomography (CT) of neck and paranasal sinus, laryngoscopy, and biopsy. Complete and detailed history taking was an essential part of diagnostic workup. All patients were subjected to single-modality radiotherapy treatment by either two-dimensional approach or through CT-based contour approach. Involvement of anterior and posterior commissure was not a criterion of exclusion. To analyze the patients after radiotherapy, patients were kept on monthly follow-up for the first 3 months; a direct laryngoscopy and contrast-enhanced CT scan of paranasal sinus and neck were done 3 months postradiotherapy. Thereafter, 3 monthly follow-up for the next 1 year followed by 6 monthly follow-up for the next 2 years and then on yearly follow. Indirect laryngoscopy and detailed clinical examination of the neck and oral cavity were undertaken during each follow-up. CT scan of the neck and paranasal sinus was done afterward as and when required.
| Results|| |
A total of 170 patients were included in the study who were treated with radiation therapy as a single modality of treatment. The patient-based characteristics are shown in [Table 1].
The treatment was radiotherapy alone with a conventional dose of 2 Gy per fraction to a total dose of 60 Gray for both Stage I and II carcinoma. External body radiotherapy with 6 MV photons using thermoplastic mask for immobilization was used. Parallel opposed portals were used with/without appropriate wedges. X-ray-based simulation was used for planning purpose. Patients were planned directly on two-dimensional (2D) simulator using bilateral parallel opposing fields with the field encompassing superiorly from the thyroid notch and inferiorly to the lower extent of cricoid cartilage and the anterior border just flashes off skin and the posterior border at the anterior edge of the vertebral body., The field sizes generally range from 5 cm × 5 cm to 7 cm × 7 cm. Some patients were planned by CT-based contour approach in which there was the involvement of anterior commissure, as shown in [Figure 1]. The gross tumor volume (GTV), clinical target volume (CTV), and the planning target volume (PTV) and the spinal cord as organ at risk were contoured. The GTV was the gross tumor visible on CT scan and the CTV included the entire larynx from below the hyoid bone to the bottom of cricoid cartilage taking into account 1 cm margin circumferentially around the GTV. PTV was given 5 mL circumferentially around the CTV as per our institution protocol. A 2D plan was made using bilateral fields and wedges for dose homogeneity.
No elective irradiation of the neck was undertaken. All patients completed the treatment within a range of 32–42 days. Break in the treatment was either due to government holiday or machine breakdown except one patient who had a treatment break of 10 days due to personal reason. None of the patients had treatment break due to radiation-induced acute toxicity. Patients were kept on monthly follow-up for the first 3 months, then 3 monthly for the next 3 months and then 6 months for the next 1 year. Direct laryngoscopy and CT of the neck and paranasal sinuses were performed at the end of 3 months after the completion of radiotherapy and there afterward when required.
Median time for recurrence as noted in our study was 9.1 months. All (100%) of the recurrences were at the local site. One patient developed nodal recurrence following total laryngectomy. Of the total recurrent cases, 86.67% were male and 13.33% were female patients, 46.67% patients had T2N0 stage glottic carcinoma and rest 53.33% had T1N0 stage glottis cancer, 33.33% patients had well differentiated, 46.67% had moderately differentiated, 20% had poorly differentiated glottis cancer, 20% cases had involvement of anterior commissure, 46.67% patients were of age more than or equal to 65 years, 86.67% patients had history of tobacco addiction. The side effects during radiation therapy such as the skin reaction and glottis edema were managed conservatively Out of these 15 recurrent cases, three patients were loss to follow-up following the confirmation of biopsy-proven recurrence, one patient did not opt for any kind of further treatment (either surgery or chemotherapy), two patients refused for salvage surgery and opted for palliative chemotherapy. One patient with T2N0 stage developed local recurrence 4 months postradiotherapy treatment completion for which he underwent total laryngectomy. The patient took a gap of 10 days during radiotherapy treatment due to personal issues and no health related issues, 19 months postlaryngectomy patient developed nodal recurrence which was biopsy proven. The patient took palliative chemotherapy for it. The local failure rate was 8.82%. LC rate was 93.65% in T1N0 stage and 84.1% in T2N0 stage. Ultimate LC rate was 91.2% as noted in our study, as depicted in [Table 2] and patient-related characteristics of locally failed patients are explained in [Table 3]. None of the patients experienced any severe skin toxicity or laryngeal toxicity as per the radiation therapy oncology grading.
|Table 3: Treatment failures and their characteristics, including gender, age, stage, histological tumor differentiation, involvement of anterior commissure, gap during treatment, and tobacco addiction of the patient who experienced recurrence|
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| Discussion|| |
The ultimate benefit of organ preservation by radiotherapy limits the surgical approach to early glottic cancer to just the biopsy of cancer. Radiation offers the benefit of organ preservation along with the achievement of better voice quality as compared to laser treatment which has been very well debated in a variety of studies. The cure rates offered by either of them are very much comparable as shown in a variety of studies and trials. Radiotherapy is the standard treatment, with excellent LC rates for early glottic cancer. Larynx, in particular early glottis has a unique characteristic due to its small field size, Several important prognostic factors have been examined, including anterior commissure involvement, beam energy, field size, daily fraction size, total dose, overall treatment time, male gender, and poor histologic differentiation. Radiotherapy, all these factors having influence on ultimate LC. Overall treatment time is known to be related to locoregional control for head and neck cancers; an analysis of two trials suggested that in node negative larynx cancer an additional dose of 0.8 Gy/day is required to control tumors with increased treatment time.,[11 Literature shows that majority of early recurrences occur within a span of 18 months in case of laryngeal cancer. Late recurrences occur till a span of 5 years. The linear quadratic model explains the value of alpha and beta and their implication of linear kill and quadratic kill components. Ratio of alpha/beta varies for different tissues and for different tumors, but for the purpose of simplicity, the values are taken as 10 for tumors, 3 for late reacting tissue, and 10 for early reacting tissue. The biological equivalent dose value for this regime of 60 Gy in 30 fractions comes out to be 72 Gy. It determines that the late reacting tissue reactions are more affected by the total dose and dose per fraction whereas the early reacting tissues are more affected by the total dose and the total treatment duration. Larynx being a late reacting tissue thus will show a better tumor control with hypofractionation which has been started to practice in various countries of the world.
| Conclusion|| |
The ultimate goal in the treatment of vocal cord cancers is voice preservation. Radiotherapy and laser excision both provide similar rates of LC. Radiotherapy proves to provide a better voice quality. However, there are side effects due to radiotherapy such as persistent glottic edema, glottic stenosis, and hypothyroidism. The recurrence rate in this study was 8.82%. Radiotherapy achieves better LC along with the benefit of organ preservation. However, surgical salvage always remains an option for failed cases. The near future will definitely see hypofractionation being practiced in the various parts of India as well.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]