Clear cell adenocarcinoma (CCA) is a rare variant of urinary bladder carcinoma with a glycogen-rich phenotype and unknown prognosis. Using the National Cancer Institute's surveillance, epidemiology, and end results (SEER) program database, we documented recent trends in incidence, mortality, demographical characteristics, and survival on this rare subtype of urinary bladder cancer. The overall age-adjusted incidence and mortality of CCA was 0.087 (95% confidence interval (CI): 0.069-0.107) and 0.064 (95% CI: 0.049-0.081) respectively per million population. In comparison to non-CCAs, CCAs were more commonly associated with younger age (<60 years old, p = 0.005), female (p < 0.001), black ethnicity (p = 0.001), grade III (p < 0.001), and higher AJCC 6th staging (p < 0.001). In addition, CCA patients more frequently received complete cystectomy (p < 0.001) and beam radiation (p < 0.001) than non-CCA patients. Our study showed a poorer prognosis of CCAs compared to all other carcinomas of the urinary bladder (p < 0.001), accounted for by higher tumor staging of CCA cases. This study adds to the growing evidence that glycogen-rich cancers may have unique characteristics affecting tumor aggressiveness and patient prognosis. Additional mechanistic studies are needed to assess whether it's the excess glycogen that contributes to the higher stage at diagnosis.
Keywords: SEER program database; clear-cell adenocarcinoma; glycogen; urinary bladder.