Bone metastases in muscle-invasive bladder cancer

Abstract

Purpose: To address the necessity of incorporating isotopic bone scan in the routine staging work-up of muscle invasive bladder cancer patients, we analyzed the data in our files to determine the incidence of bone metastasis in such patients. The rate of subsequent development of bone metastasis along the natural history of the disease was also investigated.

Patients and methods: A total of 179 files of consecutive bladder cancer patients who presented to the National Cancer Institute, Cairo University, between January 2000 and December 2001 were reviewed to check the percentage of positive bone scans on presentation and to check the subsequent development of distant metastases and bone metastasis in these patients' records.

Results: Amongst the 179 patients, 26 (14.5%) had bone metastasis on presentation, a finding that showed a statistically significant correlation with the increasing depth of muscle invasion; 61.5% of the metastatic cases had deep muscle invasion,19.2% had superficial muscle invasion and there was no muscle invasion in 7.7% (p=0.000). Transitional cell carcinoma was the pathology in 92.3% of those patients, while only 7.7% had squamous cell carcinoma (p=0.036). The cumulative 3-year incidence of bone-metastasis in the non metastatic patients after treatment mounted to 19.4 +/- 4.4%. The cumulative 3-year bone metastasis incidence in the 153 patients was higher with increasing clinical stage; 8.4 +/- 8% for c-stage 2 and 49.1 +/- 18.5% for c-stage 4 (p=0.046). As for the p-category of the tumor in the 130 patients who underwent operation, the incidence increased with higher p-stages (p=0.006). Though pelvic nodal involvement was not associated with statistically significant increase in the incidence of bone metastases, yet when incorporated as one of the 3 risk factors (grade>3, p (3) 4a and LN positive at surgery) according to which patients were grouped, there was a statistically significant difference in the incidence between patients with no risk factors, only 1 and 2 or more factors (p=0.021).

Conclusion: Meticulous search for bone metastasis alone or as a component of distant failure in the newly diagnosed bladder cancer patients is crucial to offer them the proper management and avoid undue radical surgical procedures. Thus bone scan is suggested to be performed routinely in patients with evidence of muscle invasion.