Bladder cancer collaborative stage variables and their data quality, usage, and clinical implications: a review of SEER data, 2004-2010.

BACKGROUND

Several changes were made to bladder cancer staging guidelines between the 6th and 7th editions of the American Joint Committee on Cancer (AJCC) Staging Manual. Also, Collaborative Stage (CS) Data Collection System version 2 (CSv2) implemented for 2010 Surveillance, Epidemiology, and End Results (SEER) cases involved collection of 3 new site-specific factors (SSFs): World Health Organization/International Society of Urological pathology grade (SSF1), size of metastasis in regional lymph nodes (SSF2), and extranodal extension (SSF3). Our objective was to evaluate these new SSFs to assist researchers in their use/interpretation and to describe data quality issues to be addressed moving forward.

METHODS

Staging trends were assessed for invasive and noninvasive bladder cancer cases from 2004 to 2010. Among 2010 cases, staging was compared using the AJCC 6th and 7th edition guidelines, and evaluation of completeness/quality of the SSFs was performed in relevant subgroups.

RESULTS

Age-adjusted incidence rates and proportions of cases by stage remained steady from 2004 to 2010. Changes from the AJCC 6th to 7th editions caused no substantial movement between stages. SSF1 had a known value in 82% of cases, which was higher than the traditional SEER grade/differentiation variable. SSF2 and SSF3 were less complete, with 41% and 37% having known values, respectively, among cases with lymph node involvement (according to CS lymph node variable).

CONCLUSIONS

SSF1 was more complete and straightforward to interpret than the traditional grade/differentiation variable. SSF2 and SSF3 were less complete, may be associated with data quality issues, and should only be used among cases with known lymph node involvement.