Patients were followed
up for
smoking status at six months or longer in five studies, 16 22 23 26 28 but
smoking was only measured at the time of diagnosis or treatment in four studies, 17 21 24 27 and follow -
up was not defined in one study.25 Two studies defined quitting as continuous abstinence from within six months of starting treatment to longest follow -
up, 22 23 and one study defined quitting as continuous abstinence during and after treatment.21 The remaining studies did not
give a definition of quitting.