The media play a central role in providing information and news on cancer prevention and advances in cancer research, which ultimately influence policy-making. It is therefore essential that the information disseminated is accurate and taken from credible sources. In this study, we sought to assess the quality of cancer reporting in UK newspapers and to review the credibility of the sources used for information on cancer diagnosis in the Royal Household. A total of 72 stories published in UK newspapers in the 40 days following the news of King Charles III’s and Princess Catherine’s cancer diagnosis on 5 February 2024 and 22 March 2024, respectively, contained information related to cancer and were assessed for the accuracy of the information and source credibility. About 26% of the stories were found to have made false claims related to cancer or cancer care. Misinformation was most commonly about standard cancer treatments (47% of misinformation), followed by cancer epidemiology (21%) and then complementary and alternative medicine (16%). Source credibility was variable, with most misinformation published by journalists without a health information background or quoted by individuals with no oncology or medical background. In conclusion, the quality of newspaper reporting on cancer is variable, and urgent measures should be taken to address this. Potential strategies include stricter standards for health reporting and greater transparency regarding source credibility. Closer collaboration between the press and the healthcare community is also required.