Such a test would still be very useful, when combined with other independent weak tests. If 5 weak tests in a row confirm you have cancer, then you should worry

Such a test would still be very useful, when combined with other independent weak tests. If 5 weak tests in a row confirm you have cancer, then you should worry. And anyway just report the numbers to the doctor and the patient. "This test has a 5:1 likelihood ratio, so if the odds of you having the disease were 1 to 100, it's now 5 : 100 or 1 to 20." Everyone needs to get a better grasp on probability.