Principally there are two different types of bladder cancer. Non-invasive papillary low grade tumors (pTa G1-G2) are genetically stable, recur frequently but show a low risk of progression. On the other hand there are high grade tumors (pT1-4, carcinoma in situ), which are genetically unstable, show biologically aggressive behaviour and progress. The distinction between non-invasive (pTa) and minimal-invasive (pT1) is one of the most challenging areas in bladder pathology. Due to the lack of appropriate auxiliary analysis the diagnosis is based entirely on histopathology. P53 immunohistochemistry can be helpful in the assessment of recurring high grade neoplasia. Targeted therapy in bladder cancer is particularly interesting, since a high number of oncogenes are activated and overexpressed (e.g. HER2 and EGFR).
