After being diagnosed with chronic myeloid leukemia, the first thing that often throws people is the question, "How long do I have to take this drug?" Leukemia used to be a vaguely terrifying word, but now there are truly many people who keep their daily lives almost unchanged with a single pill once a day. This is thanks to targeted therapy, the drugs commonly called TKIs. The catch is that this is not like a cold medicine you take for a few days and finish; it is a drug you have to live with for a long time, so the habit of "taking it properly" decides whether treatment succeeds or fails.
The reason consistency is stressed this much is that the drug needs to keep a steady concentration in the blood to keep suppressing the cancer cells. Forgetting a single day does not just mean missing that day's dose — the concentration swings and the effect wavers. In fact, there are reports of a fairly large difference in treatment response between people who take more than 90% of their prescribed doses and those who do not. So even if you think "what's the big deal about skipping once or twice," when those one or two times pile up, the meaning changes.
When you actually try to take it every day, it is surprisingly not easy. That is why it helps to tie the drug to a routine of your own — taking it right after brushing your teeth in the morning, or while doing the dishes after dinner, at the same time each day. Each drug has a slightly different relationship with food: some are absorbed better when taken with food, while others must be taken on an empty stomach. Also, grapefruit and grapefruit juice can interfere with the metabolism of several targeted drugs and raise the drug concentration abnormally, so it is safer to avoid them. It is good to check which case your own drug falls under when you receive your prescription.
As you keep taking it, side effects also become a concern. The skin around the eyes or the ankles may swell, you may feel nauseous, your muscles may ache, and a skin rash may appear. The most dangerous thing is to judge on your own and stop the drug because of these symptoms. Most of the time, adjusting the dose or adding a supportive prescription makes it bearable, and in many cases the body adapts as time passes. If you have a symptom that is hard to endure, do not stop on your own — speak honestly about it at your appointment. If you hide it, thinking "I should just put up with this much," you take away the care team's chance to make adjustments.
While you are taking the drug, regular tests come as part of the package. Gene testing confirms in numbers how much the cancer cells have decreased, and when this number stays deep and steady enough, some people, after discussing it with their care team, try "treatment discontinuation" — attempting to stop the drug. However, this is not something anyone can do at any time; it is decided carefully only when certain conditions are met and close follow-up is possible. It is a completely different matter from stopping on your own thinking "this should be enough."
When you travel or are prescribed a new drug for another illness, you must always tell them that you are taking a targeted therapy, because there are quite a few drugs that should not be taken together. What is written here is only general guidance, and your care team knows best the answer that fits exactly your condition and your drug. If there is anything you are unsure about, just jot it down and ask at your next appointment.