The primary purpose of this longitudinal, natural history study is to examine the feasibility of collecting web-based patient-reported outcomes (PROs) over time in unpaid informal caregivers of cancer patients during the active treatment period. Additionally, we will examine the interrelationships between self-efficacy, mutuality, psychological factors (stress, burden, and loneliness), health behaviors (Health Promoting Lifestyle Profile-II (HPLP), smoking, alcohol consumption), and health outcomes (sleep, fatigue, anxiety, depression, and cognitive function) in unpaid informal caregivers of cancer patients during the active treatment period. The primary objective of this study is to examine the feasibility of collecting web-basd PROs over time in unpaid caregivers. A sample of 129 subjects completing at least one time point is required to adequately evaluate for the planned primary analysis and evaluate the primary objectives. Recruitment began in February 2014 and closed to enrollment in July 2016. We enrolled a total of 139 subjects, with n=129 with time point #1 completed, n=85 with time point #2 completed, and n=61 with time point #3 completed.