Cancer survivorship is an emerging medical field as the number of cancer survivors is increasing annually. Due to the possible long-term side effects from cancer therapy, cancer survivors have unique medical needs. Radiation therapy for pelvic cancers (e.g. prostate, cervical, colorectal cancer), can result in severe damage to the bladder and a condition called radiation cystitis (RC). RC is characterized by inflammation, fibrosis and vascular damage resulting in lower urinary tract symptoms and hematuria. No reliable treatment is currently available, in part because the disease progression at a pathological and molecular level is poorly understood. Bladder biopsies are difficult to come by as biopsies could cause unnecessary damage to an already fragile tissue. Thus, in order to gain understanding of molecular changes to the bladder after irradiation, we analyzed urine samples from control and irradiated prostate cancer survivors for proteins with pro-inflammatory, fibrotic and vascular properties.

A total of 94 urine samples were collected from prostate cancer survivors with (n = 85) and without (n = 9) a history of external beam radiation therapy. Patients with a recent history of urinary tract infections and renal disease were excluded from the study. Of those with prior radiation exposure, 15 patients were officially diagnosed with RC prior to urine collection. Each patient ranked the presence and severity of lower urinary tract symptoms, including frequency, urgency, incontinence and hematuria. The levels of 45 proteins involved in inflammation, fibrosis and vascular homeostasis were evaluated using Multiplex Luminex Assay. Comparisons were made between control and irradiated samples, and within irradiated samples based on RC diagnosis, high symptom scores or hematuria. Statistical analysis was performed using a Welch’s t-test.

22 of the proteins analyzed were detectable in all or part of the samples. Of these, 3 fibrotic proteins (PAI-1, TIMP-1 and TIMP-2) and 2 vascular proteins (HGF and VEGF-A) were elevated within the irradiated samples when comparing for the presence or absence of RC diagnosis, hematuria or the severity of the overall symptom score. HGF was also elevated between control samples and irradiated samples. No pro-inflammatory proteins were detected in the urine, except in the urine samples of patients with gross hematuria and end stage RC.

The increase in levels of proteins involved in extracellular matrix remodeling and vascular homeostasis indicate increased activity in tissue remodeling. Despite high variability between patient samples, significant differences were detected between irradiated patients based on the presence of RC diagnosis, hematuria or high symptom scores. The lack of inflammatory proteins in the urine samples might indicate that inflammation, unlike previously thought, contributes minimally to the progression of RC and instead is an indication of end stage disease.

In this study we identified several fibrotic and vascular proteins that could play a role in the progression of RC. The findings of this study provide an insight in some of the changes occurring after irradiation that could contribute to fibrosis and vascular changes seen in bladders of pelvic cancer survivors.