Non-Invasive Tests for Bladder Cancer
By Dr. David Berman
Most people probably think of cancer tests in setting of early detection. The idea is that anyone who might wonder if they have a particular type of cancer could submit a sample of some easily obtained bodily fluid (saliva, blood, urine, sweat, etc.), send it off to the laboratory, and get a clear result. Unfortunately, developing and effectively using such a test is incredibly difficult. Perhaps the most widely used such test at the moment is the Prostate Specific Antigen blood test for prostate cancer. Some argue that use of this test has resulted in a decline in the death rate due to prostate cancer and is therefore a huge success. Nevertheless, it is clear that in a substantial number of cases, the test falsely identifies men without cancer, or incorrectly gives a clean bill of health to men who actually have the disease. You can read about the controversies here. My personal opinion is that the test, like essentially all other medical tests, requires careful use by a knowledgeable doctor and engaged patient who understand the test’s strengths and weaknesses.
In the setting of folks who have cancer and have been treated for it, non-invasive tests are very useful for monitoring cancer recurrence. PSA rises in men who have had their prostates surgically removed or irradiated are very reliable indicators of disease recurrence, for example.
Our friend Spiros effectively articulated one of the biggest issues in bladder cancer (his comment and question are here) — In patients with a risk of recurrent bladder cancer, is there a non-invasive test that we can use to supplement or replace cystoscopy? Let’s first describe cystoscopy, in case it’s useful for some readers. This is an examination of the bladder by a urologist performed by inserting a flexible tube into the urethra. The tip of the tube has a camera and a light source, and images are projected onto a video screen in the operating room or doctor’s office. Now imagine the alternative. Drop off a urine sample at the doctor’s office and be on your way. The sample is analyzed in a laboratory for protein, DNA, RNA, and/or microsocopic appearance of cells in the urine, and a report is generated.
It should work, but so far it doesn’t seem to work very well for the most common kind of bladder cancer, called low grade noninvasive urothelial carcinoma. These lesions are not harmful in and of themselves, but they carry with them an increased risk of high grade invasive cancers, which do cause harm.
It is therefore important to monitor patients with low grade carcinoma for recurrence, but especially important to monitor them for progression. Turns out that neither microscopic examination of urine cells (called cytology) nor molecular tests are very good at detecting low grade cancer, but both are pretty good at detecting high grade cancer.
Tags: Treatment