Osteoradionecrosis, dermal soft tissue necrosis, radiation cystitis, proctitis and sexual dysfunctions are well-known late-effects after radiation for cancer in the pelvic area, negatively affecting the survivors' quality of life (QOL) and psychosocial wellbeing. Increasing evidence and clinical practice support the use of hyperbaric oxygen treatment (HBOT) as an effective treatment in a variety of radiation injuries, but this is still a field with limited research and knowledge. Especially, there is a knowledge gap on how late radiation tissue injury (LRTI) influences cancer survivors' QOL and psychosocial health in a longitudinal perspective (before, along and after HBOT), as well as the patients' knowledge, expectation and experience from this treatment. This study aims to improve knowledge on these issues.

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.

QOL following HBOT:

Late-effects from cancer treatment, especially pelvic LRTI, may affect all parts of cancer survivors' life. Consequently, quality of life (QOL) is reckoned as an important outcome as it comprises physiological, psychological and social aspects of well-being. However, there is an evident research gap on how pelvic LRTI influences the patients' QOL, as well as how these outcomes develop in a longitudinal perspective. Two studies show QOL improvement in patients with chronic diabetic foot ulcers after 6 weeks. One study found significant QOL improvements from perioperative HBOT in the dimensions of pain, global health and dyspnoea in 66 patients with head and neck cancers. Another study of 101 radiation-injured patients (54% head and neck, 36 % intestine and 11% bladder) showed significant one-year improvements in the QOL dimensions of vitality and physical-, role- and social function. A significantly improved healing and increased bowel-specific QOL was found immediately after HBOT and at one-year follow-up in a randomized controlled study of 120 patients with radiation proctitis. In contrast, a systematic review state that no conclusion about HBOT's influence on QOL can be made.

In summing up, different outcomes of HBOT from pelvic radiation injured cancer survivors in a longitudinal perspective are highly requested as the existing research comprises small samples, has methodological limitations and yields scant results.

The study's goals and research questions:

This study embraces three main goals: The primary goal is to improve knowledge on how QOL is affected in survivors of pelvic cancer with LRTI, and how this may change due to HBOT. The second goal is to gain information on the patients' knowledge and expectations concerning HBOT and their experiences and satisfaction with the care along the HBOT process. The third goal is to improve knowledge on the longitudinal changes in LRTI symptoms and the patients' long-term QOL after finishing HBOT. Consequently, this study addresses the following research questions:

1. How do patients experience that the LRTI symptoms influence their everyday life?
2. What perceived information, knowledge and expectations concerning HBOT do patients express before HBOT?
3. What are the patients' self-reported LRTI burden,QOL and psychosocial health before HBOT?
4. How do LRTI symptoms change during and after the HBOT course?
5. How do QOL and psychosocial health change during the HBOT course?
6. What is the correlation between LRTI symptoms and QOL during and after the HBOT process?
7. How do patients experience the HBOT process?
8. How satisfied with care are patients along the HBOT process, and which factors do they describe as important for their satisfaction?
9. What are the patients' long-term QOL, psychosocial health and LRTI burden after HBOT?

Study design:

Based on the research questions, we will perform a mixed methods study with a prospective longitudinal embedded design. Mixed method is reckoned as the third research paradigm, and in this design quantitative data are collected longitudinal (> 3 time-points) and qualitative data are collected at two time points. This design is especially recommended where randomization is not suited or possible, and because it draws on the strengths and minimalizes the weaknesses of both quantitative and qualitative methods. Consequently, it may yield a more complete and nuanced picture of the topic, as validated questionnaires provide quantitative outcome data and in-depth interviews provide process data to explore and elaborate the quantitative results.

Recruitment and eligibility criteria: The study will recruit participants from patients that have been referred to HBOT and will undergo the treatment independently from the study. Participation in the study will neither influence whether patients are treated with HBOT, nor time or lengths or any other HBOT-related measure.

Data collection: see elsewhere

Analyses of data:

Quantitative analyses: Statistical tests will be two-tailed, with statistical significance defined as P< .05. Descriptive statistics, correlations, paired T-tests, multiple regression analyses and longitudinal analysis with linear mixed models (LMM) (or the equvalent non-Parametric tests dependent of the characteristics of the final data set) will be used for analysis of change. Effect sizes will be calculated by Cohen's d, while Z tests will be performed to analyze differences between the sample mean and the mean in the general populations.

Qualitative analysis: Systematic text condensation (STC) will be used to analyze qualitative data. This is a descriptive and exploratory method for thematic cross-case analysis of interviews. STC is a four-step analysis that includes 1) gaining a total impression; 2) identifying units of meaning; 3) abstracting the contents of individual units of meaning; 4) summarizing their importance.

Ethics:

The Regional Committee for Medical and Health Research Ethics in northern Norway has approved the project (2018/706). The study will be conducted in line with the Helsinki Declaration, providing the participants with oral and written information and written consent. As all participants will be treated with HBOT independent of inclusion in the study, we do not anticipate any negative outcomes for study-patients.

Project management, organization and cooperation:

This study is a cooperation between Center for Crisis Psychology (CCP), Faculty of Psychology, University of Bergen and Section for Hyperbaric Medicine (SHM), Department of Occupational Medicine (DOM), at Haukeland University Hospital in Bergen, Norway. A project group, chaired by CCP's research leader, May Hauken, will run the project. As HBOT represents a narrow field internationally, the study is connected to DOM's already existing international partners in the Nordic cooperation. Additionally, a multidisciplinary and international Advisory Board will be connected to the project. User involvement will be include throughout the study and include patients, representative from the Norwegian Gynecological Cancer Organization and health care professionals working with HBOT.

Progress plan and dissemination of results:

This is a 4 year project with a specific progress plan. Based on the research questions and collected data, we plan to publish at least 8 scientific papers in international peer-reviewed journals. Results will also be disseminated via lectures, popular scientific papers, national and international conferences. At the end of the project period, we will arrange a summing -up conference.

Inclusion Criteria:

1. pelvic radiation injury after intended curative radiation therapy for pelvic cancer (prostate, gynecological, and urological and bowel cancers),
2. ≥ 6 months from finished radiation therapy
3. referred to the unit for hyperbaric oxgen treatment (HBOT)
4. aged ≥ 18 years.

Exclusion Criteria:

1. severe physical and/or mental co-morbidity representing a contraindication for HBOT
2. insufficient cognitive or language skills to answer study questionnaires and perform interviews.

This study will recruit participants from all patients with pelvic radiation injury assigned to oxygen treatment (HBOT) at Section for Hyperbaric Medicine (SHM) at Haukeland University Hospital in Bergen, being the Norwegian National Center for planned HBOT.

We plan to make IPD available to other researchers on NSD (Norwegian Scientific Data).

After the study has finished, earliest in December 2022

On request