Natural history of carcinoma in situ of the urinary bladder.

Thirty-one patients with primary or secondary carcinoma in situ of the urinary bladder were followed in an intensive surveillance program to study the untreated natural history of carcinoma in situ. Few patients received any treatment for carcinoma in situ. The patients were followed for up to 14 years, to disease progression or decrease from other causes than untreated cancer. All patients except three experienced new tumour growths, of these 50% within the first year of follow-up. At 5 years of follow-up half of the patients had experienced progressing disease, i.e. muscle invasion, upper tract invasive cancer or metastases. Most patients would seem eventually to experience progressing disease. Short-term results of treatment with BCG should be viewed on background of such long-term follow-up of untreated carcinoma in situ.