The pathogenesis of radiation cystitis damages the GAG layer of the bladder mucosa. This layer protects the bladder wall from toxic agents and microorganisms; therefore, it seems that any defects in this layer cause cystitis symptoms (
20). Radiation cystitis is one of the main challenges in urology due to its unknown cause. Different remedial efforts such as radiation dose limitation and adjustment of irradiation field, oral drugs such as orgotein, vitamin E, and steroids trialed, however, were not completely successful in the treatment. The only approved oral therapy for radiation cystitis is Elmiron or pentose polysulfate sodium (
17). Intravesical use of bacillus Calmette-Guerin was also utilized for this indication; however, the findings were controversial (
21). The other intravesical therapeutic approach tested is constructed on the instillation of dimethyl sulfoxide (DMSO), which is conclusive in the management of many symptoms, but the reality that it is an organic solvent raises worries for its long-time use (
21).
Among different therapeutic options, intravesical use of some agents was reported and their response rates were 45% for chondroitin sulfate, 56% for heparin, and 44% for pentosane polysulfate (
22).
In this trial, we presented that the use of cystistat; HA; in contrast to the control arm, significantly improved the QOL and VAS and hematuria score after 9 months. HA is a main mucopolysaccharide in the epithelial, connective, and neural tissues and stands for one of the major portions of the extracellular matrix that significantly be conductive to cell proliferation and migration. Moreover, it plays the part of a defensive barrier versus irritating factors that can destroy the epithelium. It might leucocyte migration, suppress immune complexes, and boost modulation of the fibroblasts, proliferation of the endothelial cell, and improvement of the curing tissues. Impairment of the GAG layer may result in direct exposure to components of urine, to bacteria and fungi (
17). This injury can lead to radiation cystitis. Therefore, HA can be an option for the treatment of radiation cystitis. Kallestrup et al. (
16) reported higher response rates with instillation HA treatment, and the valuable effect was conserved for ≥ 3 years. Morales et al. (
23) showed that 71% of the participants who underwent HA instillations, demonstrated improvement of symptoms and disclosing the direct correlation between GAG layers, HA, and control of the IC.
Sommariva et al. (
24) prospective trial showed that sodium hyaluronate declines the symptoms of RT-cystitis. Generally, 67 (97%) patients presented complete relief of pain and dysuria.
Engelhardt et al. (
25) mentioned that after HA treatment, 50% of the subjects revealed bladder symptom remission without any additional treatment in 5-year follow-up and 41.7% of subjects with symptom recurrence revealed recovery with HA maintenance treatment. Miodosky et al. (
26) in their study concluded that HA instillations can show instant benefit in releasing the pain, macroscopic hematuria, and voiding frequency, and acceptable advantageous duration of the treatment. Vassillis et al. (
17) showed that the mean score of radiation cystitis before and after the cystistat instillations was 2.70 ± 0.47 and 1.45 ± 0.51, respectively (P < 0.01)17. Pyo and Cho in a meta-analysis showed a significantly positive effect in 6-month follow-up in interstitial cystitis patient (
27).
Shao et al. have also demonstrated that intravesical administration of sodium hyaluronate is as influential as hyperbaric oxygen therapy in the management of RT cystitis. In this randomized study of 36 cases with pelvic malignancies, this management plan was well tolerated and resulted in a reducing of pelvic pain, bladder bleeding, and urinary frequency for ≥ 12 months (
28).
Kallestrup et al. (
16) demonstrated that HA reduced the pain associated with IC, nocturia, and frequency for at least a span of 3 years.
5.1. Conclusions
This was the first study in the Iranian population indicating that patients with radiation cystitis could significantly benefit from HA, and their hematuria would be successfully resolved rather than control group, in addition to lowering the VAS score, so their QOL would be improved. Although the follow-up time was short-midterm for 9 months, the results showed the effect of time in an improving pattern. In view of the HA instillations efficacy and the absence of systemic harm effects, the management of cystistat in radiation cystitis is suggested.
5.2. Limitation and Recommendation
As a limitation, the potential effect of heparin itself on the outcome of the study in both groups can interfere with the study results.
Another study limitations are few numbers of patients in each group and short follow-up of patients, but in addition to these limitations, this study was a RCT and compared all the sub-categories of KHQ of life questionnaire between the two groups; therefore, based on the data, we can candidate patients with radiation cystitis for cystistat instillation according to their most annoying problems decreasing their QOL.