Iris Kanera

10 Chapter 1 a considerable proportion of individuals suffer from bowel complications, incontinence, and sexual problems (Capogrosso, Salonia, Briganti, & Montorsi, 2016; DeSantis et al., 2014; Stanton et al., 2015). These problems can persist for months or years, may be associated with disability and health care utilization, and can have a profound negative impact on survivors’ quality of life (QoL; Aaronson et al., 2014; Harrington, Hansen, Moskowitz, Todd, & Feuerstein, 2010; Wu & Harden, 2015). Furthermore, cancer survivors are at higher risk for cancer recurrence and comorbid conditions such as cardiovascular dysfunctions, chronic obstructive pulmonary disease, osteoporosis, and diabetes mellitus type 2 (Carmack, Basen- Engquist, & Gritz, 2011; Davies, Batehup, & Thomas, 2011; Florou, Gkiozos, Tsagouli, Souliotis, & Syrigos, 2014; Schmid & Leitzmann, 2014; Sehl, Lu, Silliman, & Ganz, 2013; Tsilidis et al., 2016). Research has shown that survivors who smoke, who are physically inactive, who have an unhealthy diet, and who are overweight, are at increased risk for morbidity, disability, mortality, and lower QoL (Carmack et al., 2011; Davies et al., 2011; Florou et al., 2014; Schmid & Leitzmann, 2014; Sehl et al., 2013; Tsilidis et al., 2016). Therefore, a healthy lifestyle is of major importance to prevent negative health outcomes and to cope with possible physical residual problems. Lifestyle in cancer survivors, more specifically healthy lifestyle promotion by an eHealth intervention is the focus of this thesis for which the rational will be explained in this introduction. What to expect from a healthy lifestyle during cancer survivorship Adopting and maintaining a healthy and active lifestyle is highly beneficial to reduce the risk of morbidity and mortality, and to improve QoL among cancer survivors (Husson, Mols, Ezendam, Schep, & van de Poll-Franse, 2015; Inoue-Choi, Robien, & Lazovich, 2013; Koutoukidis, Knobf, & Lanceley, 2015; Schlesinger et al., 2014; Sehl et al., 2013). For example, physical activity (PA) has been consistently associated with improved physical functioning, cardiorespiratory fitness, bodily strength, body composition, fatigue, psychological outcomes, and improved QoL in cancer survivors (Fong et al., 2012; Mishra, Scherer, Snyder, Geigle, &Gotay, 2014; SantaMina et al., 2014; VanDijck, Nelissen, Verbelen,Tjalma, &Gebruers, 2016). Moreover, a healthy diet is associated with healthy body weight and positive health outcomes, for example, higher vegetable consumption was associated with lower risk of cancer recurrence (Davies et al., 2011; Thomson et al., 2011). A study among persistently fatigued breast cancer survivors demonstrated that a diet rich in fruits, vegetables, whole grains, and omega-3 fatty acid-rich foods can decrease fatigue and improve sleep quality (Zick et al., 2017). In addition, smoking cessation after a cancer diagnosis was related to better performance status, a decreased risk of comorbidities, and a higher QoL (Florou et al., 2014). A recent review emphasized the effects of the inter-relationship between modifiable behavioral factors on survival and recurrence, and recommended integrating these factors in future studies (Brenner et al., 2016). In conclusion, the promotion of a physically active