Purpose:This study examined self-efficacy, self-care behavior, posttraumatic growth, and quality of life in cancer patients and their levels by disease characteristics groups to identify patient groups that require psychosocial intervention. Methods: We surveyed 107 patients using a structured questionnaire about the four factors and analyzed the factors by stratifying the patients by the period after the cancer diagnosis, by stage and by current treatment status. Results: The mean score for self-efficacy was 37.78, and that for self-care behavior 49.96. Patients who were diagnosed less than one year ago scored higher on medication, a sub-category of self-care behavior, than the post-diagnosis period of 1∼2 year group. The score was higher in the currently-treated group than the follow-up and distant metastasis groups. For posttraumatic growth, the mean was 56.17, and the factor was higher in the 1∼2 year post-diagnosis group after than the less than one year group. The score was higher in the follow-up group than the currently-treated group. With regard to quality of life, the mean score was 25.79, and no significant correlation was found with disease characteristics. Conclusion: A shorter post-diagnosis period increased self-care behavior, and the greatest posttraumatic growth was reported by the 1∼2 year post-diagnosis group. It may be necessary to provide cancer patients with an education program and other strategies less than one year after the diagnosis to improve self-efficacy and self-care behavior. To promote post-traumatic growth, it may be helpful to provide patients with psychosocial intervention within two years after the diagnosis.