"Testing can be used to show the presence of bugs, but never to show their absence!"
Every computer scientist knows (or should know -- let me not presume what today's young computer scientists know) this quotation from the famous computer scientist Edsger W. Dijkstra. Of course he was talking about the testing of computer programs.
But the same is true for the testing of humans, to see if a person carries a "bug" which could lead to problems. EWD also said that it is better to write bug-free programs to start with. Unfortunately, we don't yet seem to have the capability to do that with computer programs, or with humans, designer genes notwithstanding. May be some day, but how do we specify "correct human behaviour" so that we can be sure that the person being designed is not of the wrong kind.
For someone who has been diagnosed with an ailment, until the day comes when he or she has been "certified" to be ailment-free, each test, followed by the wait for the test results, is a "testing period". Is that why such things are called "tests"?
For an LA patient, the whole thing starts with abnormal findings on a complete blood count (CBC) "blood test", one where the numbers related to blood parameters don't fall within the expected range (see https://en.wikipedia.org/wiki/Reference_ranges_for_blood_tests) or when a person feels fatigued, experiences weight loss, joint or bone pain, or enlarged spleen. This obviously underscores the importance of regular blood tests and being conscious of any major departure from normal health condition.
Usually, a follow up test, BCR-ABL, is ordered when the doctor suspects that a person has CML or Philadelphia chromosome (Ph)-positive ALL -- two of the numerous types of LA.
(The different types of LA need to be introduced with some nontrivial background in hand. I am still unsure if I should venture into that topic here, but given the need to be informed in light of the improved LA treatment regimen -- unfortunately countered by the increase in the number of diagnosed cases -- I might.)
Getting back to testing, for most of us, the tendency is to avoid the "testing period" by not going for the tests in the first place! This is clearly the wrong
"prescription", but one that is often resorted to, with tragic consequences. Hopefully, the many messages that are broadcast these days through many media outlets, stressing the need for "cancer screening", will have the intended impact.