Background: There have been few studies of the information provided for cancer patients on the internet.
Methods: Using the Japanese language, we searched for cancer-related web pages, using the Google search engine, and evaluated the characteristics of the 150 top-ranked search results. We collected information on the operators of the websites, number of links, existence of a search function, and advertisements on the site. According to their contents, the 150 websites were classified into seven categories, of which five (numbers 1, 2, 3, 4, and 6) each accounted for 20% of the websites. The categories were: (1) media-related websites (e.g., newspapers and publishers), and portal sites; (2) patient association websites, patient's diaries, blogs by patients and/or their families (n = 33); (3) websites of medical institutions (e.g., hospitals; n = 27); (4) websites of research institutions (e.g., universities; n = 35); (5) websites of pharmaceutical companies; (6) other websites providing medical information (n = 32); and (7) other websites that did not belong to categories 1-6. Outgoing links were common in websites created by media-related organizations (median, 13) or patients and their families (median, 15), but such links were not common in the other types of websites (median, 0-4). Eight of the 13 cancer based hospitals in Japan, as well as the National Cancer Center were publishing general cancer information on their websites. Of the 13 cancer based hospitals, 12 included a link to the National Cancer Center. The National Cancer Center had the largest amount of information (736 575 words), exceeding the amount provided by the other cancer based hospitals (1 622-155 515 words). Two of the 7 websites of academic associations (included in category 6) had cancer information for patients, but the document sizes were small (3230-44 091 words).
Conclusion: The website of the National Cancer Center is the most prominent source of general cancer information for patients, but it still has room for improvement in its usability.