Cancer patients can obtain information about their illness through a variety of media sources. Therefore, it is important to know how medical journalists treat cancer-related issues; to that end, we sent self-administered questionnaires to 364 journalists in 82 organisations who had reported on medical issues for the Japanese media, asking for their reasons for reporting on cancer-related issues and the difficulties they had faced. The most common reason for reporting on health-related issues was their personal interest in a particular issue (n = 36). They mainly covered conventional therapies (n = 33), healthcare policy (n = 30), new therapies (n = 25), and diagnosis (n = 25). All of the journalists that were surveyed experienced some difficulties in reporting health issues. Significant concerns included the quality of information (n = 36), social impact (n = 35), lack of technical knowledge (n = 35), and difficulty in understanding technical terms (n = 35). Journalists commonly used personal networks, including physicians, as information sources (n = 42), as well as social media (e.g., e-mail, Twitter and Facebook) (n = 32). Topic selection was biased, with 35 of 48 journalists having never reported on topics concerning hospices. Physicians were the most trusted source of information about cancer, and journalists attached high importance to interviewing them. As medical knowledge is advancing rapidly, journalists may have increasing difficulty covering cancer-related issues.