For a screening test to be useful, the following points apply:
- The test must be easy to administer - Cxbladder is
- The test must be cheap - As it is a screening test, we are trying to pick up people (the general population) with suggestion of cancer. I'm not sure how much it costs...
- The disease must be easily treatable in the early stages, e.g. like breast cancer. We have two-yearly mammograms for women. We see a lump and we proceed onto biopsy or further confirmation tests. The lump/breast is relatively easy to remove, unlike the bladder. Bladder cancer is fairly easy to de-bulk (remove) but still requires adjuvant chemotherapy and radiation, be it brachytherapy or otherwise.
- The disease must be prevalent - Bladder cancer is not. Unsure of why the Spaniards have so much of it - perhaps they use heaps of naphthalene dye? Not sure. But overall, bladder cancer is low on our list, unlike breast, colon and prostate cancers.
- Accuracy is a moot point because we always proceed to tissue biopsy for a definitive answer. No urologist would deny a cystoscopy based on the urine test. Cystoscopy is simple, easily accessible and relatively cheap to perform with a high yield of diagnosis.
So as a screening test, it does not fit the criteria for general public use.
The other scenario is a patient comes in for a check-up. We do a urine test to check for glucose, e.g. diabetes, but low and behold blood shows up... (blood tends to be present in bladder cancer), so we go on and analyse the urine more thoroughly and image the renal tract/bladder and prostate to see if there is a mass. Depending on those results, we may refer to the urologist who will then do a cystoscopy.
What if we perform the Cxbladder test at the initial stages? The likelihood is that if positive, we will do EXACTLY the same protocol and end up with a cystoscopy, the reason being that IF the test was positive, knowing a specificity of 85%, I would not be happy because I would miss almost 1 in 5-6 patients who actually HAVE cancer and were negative on the test. I would sleep better if someone actually had a quick peep at the bladder to check for sure.
So the value as an adjunct test is also not that great, hence I see this as a risky product to float.