25 Oesophageal Cancer

Oesophageal Cancer Brachytherapy

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 10/06/2019

25 Oesophageal Cancer Brachytherapy v Razvan Galalae, Richard Pötter, Erik Van Limbergen

1. Summary 2. Introduction

3 4 5 5 6 7 8

9. Treatment planning

12 14 16 16 20 20 21

10. Dose, Dose Rate, Fractionation

3. Anatomical topography

11. Monitoring

4. Pathology 5. Work up

12. Results

13. Adverse side effects 14. Key messages

6. Indications, contra-indications 7. Tumour and Target Volume

15. References

8. Technique

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1. SUMMARY

Oesophageal brachytherapy is very effective in terms of local tumour control and more efficient than external beam radiotherapy. Thus, oesophageal brachytherapy may be used in curative indications as a boost procedure (e.g. 2 x 4-5 Gy once-weekly schedule) following downsizing with external radiotherapy giving 50 (to 60) Gy, particularly in tumours with less than 5 cm length. However, oesophageal brachytherapy may lead to substantial long-term morbidity in curative settings (ulceration, stricture, fistula), in particular if small diameter applicators are used (2-6 mm) and the dose prescription is at 10 mm from the source axis. Mucosal doses above 65-70 Gy EQD2 3 are associated with a significant increase of ulceration and stricture risk (≥G2) based on recent Japanese experience. In squamous cell carcinoma with 5 cm or less tumour length, no deep invasion (T1 or T2) and good response after external beam radiotherapy (complete or partial remission), however, level 1 evidence showed superior cause-specific survival outcomes for higher tumour EQD2 10 doses at 5 mm mucosal depth of 72.5 Gy despite consequently higher total mucosal EQD2 3 doses of about 83 Gy (see table 24.1). The main goal in avoiding severe morbidity in curative settings is to prevent the mucosal dose becoming more than twice the reference dose at 5 mm depth. This can be best achieved by using the largest possible applicator with diameter ≥10 mm; preferably 15 or 20 mm. Oesophageal brachytherapy boost used in curative indications will also reduce substantially the lung and heart dose decreasing the radiation pneumonitis risk and chronic cardiac morbidity. Delivering the oesophageal brachytherapy boost upfront followed by external radiotherapy and concomitant chemotherapy may be useful in severe obstruction to alleviate dysphagia. Oesophageal brachytherapy is the standard treatment in palliative indications with a long-lasting beneficial effect on dysphagia and a more pronounced health-related quality of life benefit than after stent placement. Combination treatments with stents are possible but may be challenging. High-dose-rate brachytherapy dominates oesophageal brachytherapy with doses per fraction of 4-6 Gy using various prescriptions. The diameter of the applicator is the key factor and has to be adjusted to the oesophageal lumen diameter at the time of brachytherapy. The applicator diameter should be as wide as possible, in particular in curative settings (>10 mm; preferably 15-20 mm). Small diameter applicators should only be used in highly obstructive lesions (palliative intent). Prescribing the dose at 5 mm from the applicator surface is important in curative settings taking into account the mucosal dose which should be significantly less than 200% of the prescribed dose. Recent Japanese experience even suggests prescribing at the mucosal surface (e.g. 2x6 Gy after 50 Gy EBRT; 72 Gy EQD2 3 ) to minimize the risk of long-termmorbidity. The corresponding tumour dose at 5 mmmucosal depth would be approximately 55 Gy EQD2 10 . In palliative settings the dose is usually prescribed at 10 mm from the source axis (e.g. 5 Gy) as only small diameter applicators (2-6 mm) can be used in obstructive lesions. Mucosal doses (e.g. 5.6 x 5 Gy in a 4 mm diameter applicator) in palliative settings should be recorded but not taken into account for the prescription when chronic morbidity is not of interest. Interdisciplinary cooperation with experienced interventional gastroenterologists is strongly recommended. In addition, treatment decisions should be taken in interdisciplinary tumour boards after careful and detailed work-up.