title: Metastatic pattern of bladder cancer: correlation with the characteristics of the primary tumor.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the metastatic pattern of muscle-invasive bladder cancer and to correlate the findings with the characteristics of the primary tumor.
  
  
  METHODS
  From a clinic population of 392 patients with muscle-invasive (pT2-4) bladder cancer seen at our institution from January 2004 through December 2009, we studied the cases of 150 consecutively registered patients with pathologically proven metastatic disease. The metastasis-free intervals and metastatic patterns of different T categories were compared by Kruskal-Wallis test and Freeman-Halton extension of Fisher's exact test. Patients were divided into two histologic categories, those with transitional cell carcinoma and those with atypical histologic features. The metastasis-free interval and metastatic pattern of these two groups were compared by Mann-Whitney test and Fisher's exact test.
  
  
  RESULTS
  The study group consisted of 150 patients (116 men [77%], 34 women [23%]; median age, 64 years). The transitional cell carcinoma group consisted of 94 (63%) patients and the atypical histologic features group of 56 (37%) patients. The most common metastatic sites were lymph nodes (104 patients, 69%), bone (71 patients, 47%), lung (55 patients, 37%), liver (39 patients, 26%), and peritoneum (24 patients, 16%). Patients with tumors of a more advanced T category had shorter metastasis-free intervals (p = 0.001, df = 2). There was no significant difference in the metastatic patterns of tumors in the different T categories. Patients with atypical histologic features had a shorter median metastasis-free interval (3 months; range, 0-29 months) than patients with transitional cell carcinoma (12 months; range, 0-192 months) (p = 0.0001). Patients with atypical histologic features had a significantly higher incidence of peritoneal metastasis (p < 0.0002).
  
  
  CONCLUSIONS
  Lymph nodes, bones, lung, liver, and peritoneum are the most common sites of metastasis from bladder cancer. Tumors in a more advanced T category and those with atypical histologic features metastasize earlier. Tumors with atypical histologic features also have a higher frequency of peritoneal metastasis.
authors.affiliation: Department of Imaging, Dana-Farber Cancer Institute, 44 Binney St., Boston, MA 02115, USA. ashinagare@partners.org
authors.forename: Atul B
authors.initials: AB
authors.lastname: Shinagare
authors.forename: Nikhil H
authors.initials: NH
authors.lastname: Ramaiya
authors.forename: Jyothi P
authors.initials: JP
authors.lastname: Jagannathan
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Fennessy
authors.forename: Mary-Ellen
authors.initials: ME
authors.lastname: Taplin
authors.forename: Annick D
authors.initials: AD
authors.lastname: Van den Abbeele
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000473:pathology*; D009361:Neoplasm Invasiveness / Q000473:pathology*; D009362:Neoplasm Metastasis / Q000473:pathology; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed; D001749:Urinary Bladder Neoplasms / Q000473:pathology*