Early and late damage in the mouse bladder after radiation combined with cyclophosphamide or cisplatinum, evaluated by two different functional assays

Radiation cystitis modeling: A comparative study of bladder fibrosis radio-sensitivity in C57BL/6, C3H, and BALB/c mice

A subset of patients receiving radiation therapy for pelvic cancer develop radiation cystitis, a complication characterized by mucosal cell death, inflammation, hematuria, and bladder fibrosis. Radiation cystitis can reduce bladder capacity, cause incontinence, and impair voiding function so severely that patients require surgical intervention. Factors influencing onset and severity of radiation cystitis are not fully known. We tested the hypothesis that genetic background is a contributing factor. We irradiated bladders of female C57BL/6, C3H, and BALB/c mice and evaluated urinary voiding function, bladder shape, histology, collagen composition, and distribution of collagen-producing cells. We found that the genetic background profoundly affects the severity of radiation-induced bladder fibrosis and urinary voiding dysfunction. C57BL/6 mice are most susceptible and C3H mice are most resistant. Irradiated C57BL/6 mouse bladders are misshapen and express more abundant collagen I and III proteins than irradiated C3H and BALB/c bladders. We localized Col1a1 and Col3a1 mRNAs to FSP1-negative stromal cells in the bladder lamina propria and detrusor. The number of collagen I and collagen III-producing cells can predict the average voided volume of a mouse. Collectively, we show that genetic factors confer sensitivity to radiation cystitis, establish C57BL/6 mice as a sensitive preclinical model, and identify a potential role for FSP1-negative stromal cells in radiation-induced bladder fibrosis.

An evaluation of the effect of bortezomib on radiation-induced urinary bladder dysfunction

PURPOSE

The urinary bladder is one major organ at risk in radiotherapy of pelvic malignancies. The radiation response manifests in early and chronic changes in bladder function. These are based on inflammatory effects and changes in urothelial cell function and proliferation. This study evaluates the effect of bortezomib as an anti-proliferative and anti-inflammatory compound in an established mouse bladder model. The early radiation-induced bladder dysfunction in the mouse occurs in two phases during the first month after irradiation (phase I: day 0-15, phase II: days 16-30).

MATERIALS AND METHODS

Daily bortezomib injections (0.02 mg/ml, subcutaneously) were administered between days 0-15 or 15-30 in separate groups. Single graded radiation doses were administered in five dose groups. Cystometry was carried out before (individual control) and during the first month after irradiation. When bladder capacity was decreased by ≥50%, mice were considered as responders. Statistical analysis was performed by the SPSS software version 24.

RESULTS

Daily bortezomib injections between days 0-15 resulted in a significant decrease in responders for phase I. There was no significant effect with daily bortezomib injections between days 16-30.

CONCLUSION

Two separate waves of acute radiation-induced urinary bladder dysfunction have distinct mechanisms that need further biological studies.

Influence of animal husbandry practices on void spot assay outcomes in C57BL/6J male mice

AIMS

Mice are increasingly being used as models to investigate aspects of urinary dysfunction that humans with lower urinary tract symptoms (LUTS) experience. One method used to examine voiding function is the spontaneous void spot assay. The purpose of this study was to characterize and identify animal husbandry conditions that might confound results of the spontaneous void spot assay in male C57Bl/6J mice.

METHODS

Mice were placed in cages lined with filter paper for 4 hr and urine was visualized with UV transillumination. Voiding parameters including urine spot number, spot size, total urine area, primary void area, corner and center voiding were quantified.

RESULTS

Adult male mice void more frequently with advancing age and a subpopulation (5-10%) display a frequent spotting pattern at 6-9 weeks of age. Voiding was not significantly different in male mice weaned to group housing (4-6 per cage) versus single housing, and was not altered when they were used as breeders. Voiding was changed upon transferring group housed adult males to single density cages, which decreased total urine area. Repeated assays of male voiding behavior over three consecutive days increased primary void area by the third day of monitoring and revealed that voiding behavior is impacted by routine cage changes and time of day.

CONCLUSIONS

Together these results identify housing and husbandry practices that influence male voiding behaviors in the spontaneous void spot assay and will inform voiding behavior analyses conducted with male C57Bl/6J mice.

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

Late effects on the urinary bladder in patients treated for cancer in childhood: a report from the Children's Oncology Group

Childhood cancer survivors who have had pelvic or central nervous system surgery or have received alkylator-containing chemotherapy or pelvic radiotherapy as part of their cancer therapy may experience urinary bladder late effects. This article reviews the medical literature on long-term bladder complications in survivors of childhood cancer and outlines the Children's Oncology Group Long-Term Follow-up (COG LTFU) Guidelines related to bladder function. An overview of the treatment of bladder late effects and recommended counseling for survivors with these complications are presented.

Late complications of pelvic irradiation in 16 dogs

When external beam radiation therapy is administered to the pelvis, normal tissues irradiated may include the colon, small intestine, urethra, bladder, bone, and spinal cord. The objectives of this retrospective study were to determine the incidence and severity of late radiation effects following pelvic irradiation in dogs and to identify factors that increase the risk of these effects. Medical records of all dogs treated with curative intent external beam radiation therapy to the pelvic region between 1993 and 1999 were reviewed. Patients with follow-up longer than 9 months or any patient that developed late complications earlier than 9 months were evaluated. Sixteen dogs met criteria for inclusion in this study. All dogs were treated with a 6-MV linear accelerator with bilaterally opposed beams. Diseases treated included transitional cell carcinoma of the bladder, transitional cell carcinoma of the prostate, and anal sac apocrine gland adenocarcinoma. Four dose/fractionation schemes were used: 49.5 Gy in 3.3 Gy fractions, 54 Gy in 3.0 Gy fractions, 54 Gy in 2.7 Gy fractions, and 18 Gy intraoperative radiation therapy followed by 43 Gy external beam radiation therapy in 2.9 Gy fractions. Implantable chemotherapy in the form of an OPLA-Pt sponge was used in six dogs as a radiation potentiator. Colitis was the major late effect following pelvic irradiation, occurring in nine dogs (56%). Colitis was characterized as mild in three dogs, moderate in one dog, and severe in five dogs. Three of the dogs with severe effects suffered gastrointestinal perforation. All dogs with severe late effects received 3 or 3.3 Gy per fraction, and 80% received radiation potentiators. In the seven dogs that received 2.7 Gy or 2.9 Gy per fraction, late effects were classified as none (n = 5), mild colitis (n = 1), and moderate colitis (n = 1). Radiation therapy can be administered to the pelvic region with a minimal risk of late effects to the colon by giving smaller doses per fraction and avoiding systemic radiation potentiators.

Lower urinary tract function after intra-arterial chemotherapy with concurrent pelvic radiotherapy for invasive bladder cancer

BACKGROUND

Intra-arterial chemotherapy with concurrent pelvic radiotherapy as a bladder-sparing regimen for invasive bladder cancer is highly promising for selected patients. However, lower urinary tract function after this treatment has not been fully investigated.

METHODS

The urodynamic effects of intra-arterial chemotherapy with concurrent pelvic radiotherapy were retrospectively evaluated in 14 patients with organ-confined invasive bladder cancer. The post-treatment urodynamic findings were compared with the pretreatment ones (n = 7), and a comparison was made between the serial urodynamic findings after the treatment in another seven patients who were able to undergo the pretreatment urodynamic study (UDS).

RESULTS

The median follow-up period up to the latest UDS was 34 months. Of the 14 patients, the latest UDS revealed some storage dysfunctions in 11 (79%) and some emptying dysfunctions in three (23%). Uninhibited detrusor contraction and decreased bladder compliance were recorded in 29 and 43% at the pretreatment UDS and approximately 50-60 and 20-60% in the serial follow-up studies, respectively (n = 7). Impaired detrusor contractility lasted in one patient. In the seven patients without the pretreatment UDS, decreased maximum cystometric capacity and decreased compliance were recorded in approximately 50-60 and 20-60% at the serial UDS, respectively. Detrusor contractility was aggravated in one patient and completely lost in one with time.

CONCLUSIONS

The urodynamic findings indicate that the bladder-sparing regimen might result in perpetuating the lower urinary tract dysfunctions due to invasive bladder cancer itself and/or transurethral surgery and might injure the infrasacral autonomic nerves and the bladder itself.

Concurrent cisplatin-based radiotherapy and chemotherapy for locally advanced cervical cancer

BACKGROUND AND METHODS

On behalf of the Gynecologic Oncology Group, we performed a randomized trial of radiotherapy in combination with three concurrent chemotherapy regimens -- cisplatin alone; cisplatin, fluorouracil, and hydroxyurea; and hydroxyurea alone -- in patients with locally advanced cervical cancer. Women with primary untreated invasive squamous-cell carcinoma, adenosquamous carcinoma, or adenocarcinoma of the cervix of stage IIB, III, or IVA, without involvement of the para-aortic lymph nodes, were enrolled. The patients had to have a leukocyte count of at least 3000 per cubic millimeter, a platelet count of at least 100,000 per cubic millimeter, a serum creatinine level no higher than 2 mg per deciliter (177 micromol per liter), and adequate hepatic function. All patients received external-beam radiotherapy according to a strict protocol. Patients were randomly assigned to receive one of three chemotherapy regimens: 40 mg of cisplatin per square meter of body-surface area per week for six weeks (group 1); 50 mg of cisplatin per square meter on days 1 and 29, followed by 4 g of fluorouracil per square meter given as a 96-hour infusion on days 1 and 29, and 2 g of oral hydroxyurea per square meter twice weekly for six weeks (group 2); or 3 g of oral hydroxyurea per square meter twice weekly for six weeks (group 3).

RESULTS

The analysis included 526 women. The median duration of follow-up was 35 months. Both groups that received cisplatin had a higher rate of progression-free survival than the group that received hydroxyurea alone (P<0.001 for both comparisons). The relative risks of progression of disease or death were 0.57 (95 percent confidence interval, 0.42 to 0.78) in group 1 and 0.55 (95 percent confidence interval, 0.40 to 0.75) in group 2, as compared with group 3. The overall survival rate was significantly higher in groups 1 and 2 than in group 3, with relative risks of death of 0.61 (95 percent confidence interval, 0.44 to 0.85) and 0.58 (95 percent confidence interval, 0.41 to 0.81), respectively.

CONCLUSIONS

Regimens of radiotherapy and chemotherapy that contain cisplatin improve the rates of survival and progression-free survival among women with locally advanced cervical cancer.

Late changes in the normal mouse bladder after irradiation alone or in combination with cis-DDP or cyclophosphamide, assessed by stereological analysis

Stereological analysis has been performed to investigate the late changes in the normal mouse bladder one year after radiation alone (10-25 Gy) or radiation (10-15 Gy) combined with cyclophosphamide (CTX), 100 mg/kg, or cis-diamminedichloroplatinum (II) (cis-DDP), 6 mg/kg. A significant increase in total volume of urothelium was found in the group treated with CTX combined with radiation compared with the control. The total volume of connective tissue in the muscular layer in the groups which received X-rays only showed a significant increase compared to the control. There also seemed to be an increase in the amount of connective tissue in muscular tissue, although this was not statistically significant, in the groups treated with CTX and irradiation compared with CTX alone. This indicates the importance of radiation in the development of late damage. Results from bladders treated with cis-DDP alone or combined with radiation were statistically inconclusive due to the small number of animals in each group. The group treated with CTX and radiation (15 Gy) showed a significant decrease in the total volume of lamina propria, but no difference was found in the other treatment groups when comparing connective tissue, the muscular layer or the amount of vessels and capillaries with their corresponding control groups. Stereological analysis seems a feasible method to demonstrate late bladder tissue changes encountered after irradiation alone or combined with chemotherapy.