Information on patient quality of life (QOL) is essential to many clinical decisions. Therefore, studies that aim to extract QOL information from patient narratives are increasingly drawing attention. Also, several studies have noted that web services for patients, such as patient social networking services, may represent promising resources for QOL research. However, it is still unclear whether patient narrative text contains corresponding amounts of QOL information as self-reported QOL. This study investigates if medical staff can accurately estimate patient QOL from only patient narrative texts. We analyzed (1) QOL of cancer patients estimated by medical staff from patient autobiographical texts and (2) self-reported QOL scores of cancer patients. We compared patients from the following 3 disease groups: (1) gastrointestinal cancer, (2) breast cancer, and (3) lymphoma. The SF-36v2™ Health Survey was used to measure patient QOL in both materials, and the QOLs were compared. We found significant differences between self-reported QOL and estimated QOL in breast cancer patients and lymphoma patients, but not in gastrointestinal cancer patients. In particular, the medical staff tended to underestimate physical QOL scores. Medical staff may underestimate several aspects of QOL scores. On the basis of these results, we may be able to achieve more precise QOL estimation from patient narratives.