October 08, 2014
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Radical cystectomy, urinary diversion increased fracture risk among patients with bladder cancer

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Patients with bladder cancer who underwent radical cystectomy and urinary diversion demonstrated an increased risk for bone fracture, according to results of a population-based study.

Radical cystectomy and urinary diversion may cause chronic metabolic acidosis, potentially leading to long-term bone loss in patients with bladder cancer. However, the association between radical cystectomy and fracture risk had not been established.

Amit Gupta, MD

Amit Gupta

Amit Gupta, MD, MPH, of the departments of urology and epidemiology at University of Iowa, and colleagues used the SEER-Medicare–linked database from 2000 through 2007 to identify 50,520 patients with stage 0 through stage III bladder cancer. Researchers assessed the association between radical cystectomy and risk for fracture at any site.

Gupta and colleagues determined 4,878 (9.6%) patients in the cohort had cystectomy and urinary diversion.

During median follow-up of 41 months, 10,872 patients experienced a fracture. Of them, 792 had undergone cystectomy and urinary diversion, and 10,080 had not undergone cystectomy.

Median time to fracture was 16.6 months from cystectomy (interquartile range, 6.2-35.4) among patients who underwent cystectomy and 21.8 months (interquartile range, 8.3-42.2) from cancer diagnosis among those who did not undergo cystectomy.

The fracture rate was 6.55 per 100 person-years in the cystectomy group vs. 6.39 per 100 person-years among those who did not undergo cystectomy.

After controlling for disease and patient characteristics, researchers determined cystectomy was associated with a 21% increased risk for fracture (adjusted HR=1.21; 95% CI, 1.1-1.32).

The increased risk for fracture was most apparent among patients aged 66 to 69 years (adjusted HR=1.83; 95% CI, 1.47-2.29), followed by those aged 75 to 79 years (adjusted HR=1.29; 95% CI, 1.08-1.53) and those aged 70 to 74 years (adjusted HR=1.13; 95% CI, 0.93-1.37).

The increased risk for fracture was most apparent among patients with stage 0 disease (adjusted HR=1.48; 95% CI, 1.1-1.99), followed by those with stage III disease (adjusted HR=1.39; 95% CI, 1.09-1.77), stage I disease (adjusted HR=1.27; 95% CI, 1.11-1.44) and stage II disease (adjusted HR=1.04; 95% CI, 0.86-1.25).

“Interestingly, patients who had cystectomy seemed to have fewer risk factors for fracture at the time of cancer diagnosis, given that they were generally younger, had fewer comorbidities, were less likely to have chronic kidney disease and had a lower incidence for fractures in the year before diagnosis,” Gupta and colleagues wrote. “Despite these favorable characteristics, after cystectomy their risk for fracture was increased by 21%, compared with their peers who did not have cystectomy. These findings emphasize the need to monitor bone health and to conduct trials of prophylactic therapies that may reduce the risk of fracture in these patients.”

Disclosure: The researchers report no relevant financial disclosures.