Japan's Action Plan for Whole Genome Analysis states the need for patient and public involvement (PPI). We conducted an online survey and group discussion with members of the “Patient and Public Panel” at the National Cancer Center. The objective of our activities was to clarify cancer patients' interest in whole genome analysis (WGA) and their thoughts about PPI for WGA. The online survey was conducted before and after the group discussion. Respondents expected their genetic information to be used “for basic research on diseases at universities and other institutions for the benefit of future generations” and were concerned about “information leakage and misuse.” The percentage of respondents who had no concerns about the utilization of their genetic information decreased by 17.1 points and the percentage of those who were concerned about “finding out the risk of diseases I do not want to know about” increased by 11.8 points after the group discussion. The participants discussed the provision of information about WGA, concerns about WGA, willingness to participate in WGA, reasons why PPI is needed in WGA and its challenges, and the PPI activities they can join. Based on the results of the group discussion and online survey, potential WGA participants will be likely to value the information on measures against information leakage, support when a genetic disease is detected, and measures to protect genetic information and prevent disadvantages regarding genetic information. Collaboration with potential WGA participants will be instrumental in promoting PPI in WGA. Clarifying and sharing the patients' benefits of PPI with the public will motivate them to become involved.