How Doctors Measure Success
Doctors judge whether a MEK inhibitor is working in two main ways: by measuring the tumor on MRI scans and by asking how you’re feeling, including your pain and how well you can move and function, says Giglio.
Tumor Volume
Plexiform neurofibromas are measured with volumetric MRI, which calculates a tumor’s full three-dimensional size. In clinical trials, a tumor was considered responsive to treatment if it shrank by at least 20 percent and the change held up on a second scan two to six months later.
Because tumors take months to start shrinking, an MRI about every six months is reasonable, though there’s no hard-and-fast rule, says Brown. “If we scan too early and don’t see a change yet, patients can get discouraged,” she says.
Function and Quality of Life
In clinical trials, people rate their worst tumor pain on a scale of 0 to 10 and fill out questionnaires on how much pain gets in the way of daily life and on their overall quality of life.
