People who take cancer treatments in pill form at home may not be using the medicines properly.
A study by Michigan State University found that more than 40 percent of people took too many pills or missed doses of their oral cancer medications.
"Unfortunately, that can mean that it's not combating the cancer, or the medication is not able to work because the patient hasn't received enough of the medication," says Sandra Spoelstra, an assistant professor at MSU's College of Nursing.
Spoelstra says some oral anti-cancer agents are taken just once a day.
"But about half are very complex, and they have what they call cycling -- where you take it for three weeks, then you're off a week or 10 days, and then you start the meds again," she explains. "On occasion, certain patients have to take two oral anti-cancer agents at the same time, which can be very complicated if they're on different schedules."
Spoelstra says patients sometimes stopped taking their medications because of unpleasant side effects, including nausea.
She says not following the proper regimen can also be expensive.
"Sometimes a single pill can cost $600 or $800. I think people need to understand the cost of their pills and how important it is that they need to take them."
Spoelstra says medication instructions can be confusing and often require more than a simple pill box to keep track of what to take and when.
She says using reminders, such as text messages and smart-phone alarms can help. Caregivers can also help keep track of medications.
Medical providers also should play a bigger role, says Spoelstra.
"We need to figure out how to better inform patients when they're first starting their regimen," she says. "They may be distressed if they're just finding out they have cancer or changing from IV to pills because their cancer has progressed. Sometimes they don't absorb the information."