Tepilta® Versus Oxetacaine, Antacids and Placebo

Inclusion Criteria: 1. Male or female ≥ 18 years. 2. Score = 0 on NRS for oesophageal pain. 3. Radiotherapy (RT) or combined radio-chemotherapy (RCT) of a solid tumour in head/neck/thorax region. A minimum length of 5 cm of the oesophagus must be included in high-dose radiation field. 4. Duration of RT 5 to 8 weeks. 5. Single radiation dosage of fractionated RT 1.8 to 2.0 Gy/day, of intensity-modulated RT (IMRT) 1.5 to 2.3 Gy/day, each for 5 days a week (single frequency deviations are allowed presuming that intended duration of RT remains 5 to 8 weeks). 6. First radiation in the intended radiation area. 7. Written informed consent. Randomisation criteria: 8. Appearance of oesophageal pain as follows: Score ≥ 2 on Numeric Rating Scale (NRS) for pain during main daily meals is reached at least once. 9. At least 20 Gy of the dose of radiation therapy in oesophageal area remaining. 10. Oesophageal symptoms of grade ≤ 2a according to the adapted Common Terminology Criteria for Adverse Events CTCAE. Exclusion Criteria: 1. History of allergic reaction to the study medication or its excipients (i.e. aluminium or magnesium hydroxide, oxetacaine, any other ingredient of study medication). 2. Pregnancy, breast-feeding or planned pregnancy during the study. 3. Known hypermagnesaemia. 4. Known hypophosphataemia. 5. Clinically significant obstipation, as judged by the investigator. 6. Acute appendicitis. 7. Total intended radiation dose at lips and the anterior oral cavity \> 60% of total intended radiation dose at the swallowing process (pharynx, oesophagus). 8. Hyper-fractionated RT. 9. Intended naso-gastral tubes. 10. Primary tumour of the cranial base, brain, oral cavity, lips, naso-pharynx, para-nasal sinuses. 11. Known bone metastases. 12. Reflux oesophagitis 3 months prior to the study. 13. Continuous systemic pain treatment at the beginning of RT. Systemic pain medication for oesophagitis prior to randomisation must not be taken. 14. Concomitant treatment with tetracyclines, cinolone derivatives (ciprofloxacin, ofloxacin, enoxacin, norfloxacin), cheno-desoxycholic acid, sodium fluoride, local anaesthetics (other than those used as study medication). 15. Patients relying on levothyroxine after resection of thyroid carcinoma being hypothyroid and patients relying on levothyroxine due to other reasons not being euthyroid. 16. Artificial nutrition at the beginning of radiation. 17. Drug (licit and illicit) or alcohol abuse which would interfere with the patient's proper completion of the study. 18. Exposure to an investigational product within the last 4 weeks, simultaneous exposure to another investigational product. 19. Lack of ability or willingness to give informed consent. 20. Anticipated non-availability for study visits / procedures. 21. Lack of ability or willingness to keep patient's diary. 22. Lack of willingness to have personal study related data collected, archived or transmitted according to the protocol. 23. Vulnerable subjects.