Iris Kanera

5 115 Lifestyle-related effects of the Kanker Nazorg Wijzer many days a week are you moderately physically active for at least 30 minutes (e.g., cycling, brisk walking, household, gardening, sports, or other activities)?” (van Stralen et al., 2009). Prior studies supported the reliability and validity of single-item self-report measures for PA (Milton, Bull, & Bauman, 2011; Milton, Clemes, & Bull, 2013). Moreover, reliability and validity of the SQUASH was confirmed in previous research among patient populations (Arends et al., 2013; Wagenmakers et al., 2008). Dietary behavior For assessing vegetable, fruit, whole grain bread and fish consumption, relevant items of the Dutch Standard Questionnaire on Food Consumption were used at baseline and after six months (van den Brink et al., 2005). The number of days per week when products are consumed were asked for each of the food categories (e.g., “How many days a week do you eat fruit?”), ranging from 0 - 7. In addition, the number of servings per day was assessed for fruit (one serving is equal to 100 g), vegetables (one tablespoon is equal to 50 g), whole grain bread (slices), and fish (servings). The mean daily consumption was calculated by multiplying the number of days by the amount of servings and dividing this by 7 days a week. For fish, servings per week were measured, and the mean weekly consumption was calculated. Outcome measures for dietary behavior in the present study were vegetable consumption in grams per day (g p/d), fruit consumption in servings p/d, whole grain bread consumption in slices p/d, and fish consumption in servings p/w. Previous research supports the reliability and validity of a similar food frequency questionnaire assessing vegetables en fruit among women (Bogers, Van Assema, Kester, Westerterp, & Dagnelie, 2004). Smoking behavior Standardized questions from Dutch Measuring Instruments for Research on Smoking and Smoking Cessation were used to assess smoking behavior (Mudde et al., 2006). Based on a combination of three items, current and former smoking behavior was measured at baseline (i.e., “Do you currently smoke”; “Did you smoke in the past?”; “How long ago did you stop smoking?”), and categorized into never-smokers , former smokers and current smokers . At follow-up, four items were used to assess smoking behavior. This behavior was categorized into current smokers (“I still smoke, and I did not attempt to quit), never-smokers (“I never smoked, I’m a non- smoker”), and former smokers (“I have not smoked a single puff since quitting”). It was also measured whether participants who smoked at baseline quit smoking by means of the standardized 7-day point prevalence abstinence question (“Have you smoked one or more cigarettes/cigars/pipes during the past seven days”; Hughes et al., 2003; Velicer & Prochaska, 2004). To identify the intervention effect after six months on smoking behavior ( yes = 0, no = 1), only the subsample of participants who were smokers at baseline was analyzed.