Prognosis is difficult to discuss with patients who have advanced cancer and their families.This study aimed to explore the experiences of families of patients with cancer in Japan in receiving prognostic disclosure, explore family perception of the way the prognosis was communicated, and investigate relevant factors of family-perceived need for improvement.A multicenter questionnaire survey was conducted with 666 bereaved family members of patients with cancer who were admitted to palliative care units in Japan.In total, 86.3% of the families received prognostic disclosure. The overall evaluation revealed that 60.1% of the participants felt that the method of prognostic disclosure needed some, considerable, or much improvement. The parameter with the highest value explaining the necessity for improvement was the family perception that the amount of information provided by the physician was insufficient (beta=0.39, P<0.001). Furthermore, the family perception that they had lost hope and that health care providers failed to facilitate preparation for the patient’s death had significant direct effects on the necessity for improvement (beta=0.21, P<0.001; and beta=0.18, P<0.001, respectively). The feelings for the necessity for improvement also were affected significantly by seven communication strategies (i.e., not saying “I can do nothing for the patient any longer,” pacing explanation with the state of the patient’s and family’s preparation, saying “We will respect the patient’s wishes,” making an effort to understand the family’s distress, being knowledgeable about the most advanced treatments, assuring continuing responsibility as the physician for medical care, and respecting the family’s values).This model suggests that strategies for care providers to improve family perception about prognostic disclosure should include 1) providing as much prognostic information as families want; 2) supporting families’ hopes by keeping up with up-to-date treatments and by assuring the continuing responsibility for medical care; 3) facilitating the preparation for the patient’s death by providing information in consideration of the family’s preparations and values; 4) stressing what they can do instead of saying that nothing can be done for the patient; and 5) assuring the family that they will respect the patient’s wishes.