Because tumors are made of our own body cells and not from foreign substances, they are not rejected by our immune system or inflammation. It is only when the tumor grows large enough to create a sign or symptom, that it will present itself either to an examining physician or to the individual him/herself. It is the nature of the organ with respect to its function and its anatomy that will aid in the detection of a tumor that might reside within it.

In the case of bladder tumors, several signs and symptoms may occur. Because a cancerous tumor is made up of very abnormal cells along with abnormal blood vessels, they tend to be very "friable". That is, the integrity of the tissue of the tumor itself is ironically unstable. Therefore, it may not only shed its abnormal cells into the urine, but also it can bleed-either microscopic amounts of blood that are undetectable to the human eye, or in fewer cases, visible blood in the urine. Indeed, microscopic blood in the urine- microscopic hematuria- is the single most common sign. It should be noted, however, that the converse is hardly true. That is, most individuals who have microscopic hematuria DO NOT have bladder cancer.

Beyond examining the urine microscopically for traces of blood, a finding of far greater specificity for the detection of transitional cell carcinoma is the detection of actual cancerous-appearing cells in the urine. Urine cytology is very similar to the Pap smear for cervical cancer in women. A positive test warrants a thorough examination of the urothelium.

In addition, the presence of a tumor along the lining of the bladder can result in increased sensitivity of the bladder and symptoms, known as irritative voiding symptoms. These less common symptoms, including frequent urination and urgency, occur because the bladder often is more irritated and thereby factors abnormally in the presence of the diffuse involvement of the bladder lining with abnormal cells.