Pelvic Radiation Injuries After Cancer Treatment: Symptoms, Quality of Life and Experiences Before, Along and After Hyperbaric Oxygenation Treatment

Late effects following radiation of pelvic cancers:

Annually, more than 32000 Norwegians are diagnosed with cancer where approximately 70% will be alive 5 years after diagnosis. About 50% of all cancer patients receive radiation as part of their multimodal cancer treatment, and 50% of these will be long-term survivors. Irradiation therapy is an essential part of the curative treatment of pelvic malignancies, including rectal, uterine and cervical carcinoma. Although precautions and advances are taken, radiation may affect surrounding healthy tissue and lead to acute or chronic radiation injury. About 5-15% of the patients experience late radiation tissue injury (LRTI) that develops months or years after radiation, characterized by poor microcirculation with hypoxia, tissue damage and fibrosis. Consequently, frequent late-effects are related to radiation cystitis, proctitis and enteritis, soft tissue necrosis (skin and vagina) and fistulas with increased frequency, urgency and leakage of urine or faces, diarrhoea and pain. Although these late- effects obviously interfere significantly with the survivors' quality of life (QOL) and psychosocial health, research regarding these consequences is extremely limited.

Hyperbaric oxygen treatment (HBOT) for pelvic LRTI:

HBOT is a treatment modality where the patient is placed in a pressure chamber breathing 100% oxygen while exposed to elevated ambient pressure. HBOT for pelvic LRTI typically involves a treatment pressure of 2.4 ATA Atmospheres Absolute) while breathing oxygen once daily for about 90 minutes for 6 weeks (about 30 'dives' in total). HBOT for LRTI is based upon its ability to increase tissue oxygenation, stimulate neoangiogenesis and cellular regeneration and thereby induce revitalizing and healing of damaged tissue. Although HBOT is a time- consuming treatment, it is well accepted and tolerated by the patients, with few and usually harmless side effects.

Previous studies on the effect of HBOT to reduce pelvic LRTI have not yet yielded broadly accepted and conclusive results. The available studies indicate that HBOT has a positive effect on a variety of conditions, although some studies report no effect. A Cochrane review concludes that HBOT may improve outcomes in various kinds of cancer related radiation injuries (e.g. head and neck, proctitis, osteoradionecrosis), suggesting that other tissues also are likely to respond (e.g. bladder). However, these studies operate with very heterogeneous timepoints for follow-up, varying from right after HBOT is finished to several weeks, months or years after, which may have influenced the outcomes. However, we could not find any publication stating the course of symptomatic improvement for pelvic LRTI. This knowledge-gap is a challenge when informing patients and handling their expectations for this treatment.