Cancer is the leading cause of death in Japan, and over 360,000 Japanese died of it in 2011 [1]. About half of all Japanese are expected to be diagnosed with cancer during their lifetime [1], and approximately 805,000 new cancer cases were diagnosed in 2010 [2]. However, cancer mortality can be reduced through screening and early detection [3,4]. Thus, it is important to enhance screening in the population. Moreover, cancer incidence would be preventable through lifestyle choice and behaviour changes such as stopping smoking, reducing alcohol consumption, eating a balanced diet, engaging in physical activity, and reducing BMI [1,5,6]. Indeed, the prior study estimated that 42.7% of Japanese cancer incidence and 42.6% of mortality could potentially be preventable [7]. However, general awareness of the attributable fraction of cancers being caused by major lifestyle factors was low in Japan [8].

Previous studies indicated that effective health communication could play a significant role in shaping individuals’ cancer-related decisions and behaviours [9-13]. Providing information about cancer prevention such as risk factors and preventive behaviours might increase awareness of prevention and promote such behaviours. Indeed, a number of researchers have indicated that obtaining information was positively associated with increased knowledge about cancer, and adoption of preventive and screening behaviours [14-17]. It is therefore necessary to develop effective health communication strategies that aim to inform about cancer based on solid evidence. A greater understanding about the prevalence and correlates of obtaining information about cancer might enable to identification of specific subgroup to target for interventions. Moreover, it might contribute to the design of effective strategies for promoting cancer-preventing behaviours. Several previous studies have identified that sociodemographic characteristics and cancer history were associated with cancer information seeking [9,14,18-21]. Recently, behaviours of obtaining information about cancer and the influence of obtaining cancer information on cancer preventive behaviours have been investigated by sociodemographic characteristics such as gender and race/ethnicity in the United States [10-13,22]. Nevertheless, little is known about how Japanese people obtain cancer information.

Moreover, to develop effective communication using cancer-related information, it is important to determine whether specific information sources are more effective than others and to evaluate needs for information about cancer. Hence, a number of studies about needs and sources of cancer information have been conducted with patients or their families [23]. However, few studies have assessed the preferences of the general public about sources and contents of cancer information.

Therefore, the present study examined the prevalence and demographic correlates of obtaining information about cancer among Japanese adults, and their preferences for sources and contents of cancer-related information.

This is the first study assessing behaviours and preferences around obtaining information about cancer in Japan. Information about cancer had been obtained by less than half of those responding, which was similar to levels seen in previous studies [18,20,21,24]. However, this level may not be sufficient. This result implies that efforts to inform people about cancer might be not enough to reach a large proportion of the population. Effective health communication strategies about cancer are therefore required to promote cancer preventing lifestyle changes, including attending cancer screening.

The current study found that some sociodemographic characteristics are significantly correlated with obtaining information about cancer. Women were more likely to obtain information about cancer, which is consistent with previous studies [6,18,21]. In contrast, the number of deaths from and incidence of cancer was larger in men. The results suggest that a communication strategy focused on men is particularly important. Older age groups were found to be more likely to obtain information about cancer among Japanese adults. This result is inconsistent with prior studies that indicated older respondents were less likely to seek information about cancer [18,20,21,25]. People often tend to seek and receive cancer information from mass media including television and print media [26]. In Japan, older people tend to watch more television [27] and have a higher rate of newspaper subscriptions [28] than other age groups. Thus, older age groups may also have more opportunity to obtain information about cancer. The finding suggests that the information about cancer is not reaching younger people compared to older people. It is important for a young age to adopt preventive behaviours before getting cancer. Furthermore, cancer has been increasing across all age groups, including younger people recently [1]. Thus, greater effort to inform younger people is needed. Respondents with a previous history of cancer or those with family, friends, or co-workers having a history of cancer were more likely to obtain information about cancer. Experience of feeling closer to cancer might enhance their interest in cancer compared with those not having cancer history.

This study also examined the preferred sources of information about cancer. Mass media such as television/radio, Internet, and newspaper were the most common source of information about cancer among Japanese adults. These findings were consistent with those of other studies [12,18,21]. Previous study indicated that mass media had a considerable influence on cancer communications, because it could attract and hold the attention of those at cancer risk [29]. Moreover, attracting and holding public attention through mass media could help motivate individual behavioural change [26]. The effective use of mass media could contribute to delivering cancer information to Japanese adults. Therefore, future research should explore specific and effective ways to using mass media.

Additionally, the present study revealed the contents of cancer information both obtained and needed. The most frequently obtained content was about screening, symptoms, and treatment, which is consist with a previous survey [18,30]. In the present study, contents of cancer information which respondents needed were similar to contents which respondents obtained. However, some needed contents of cancer information were inconsistent with the frequently obtained content such as prevention, medical expenses, and coping. The finding suggests that it is necessary to provide additional information to satisfy expectations. In particular, contents of prevention are needed to inform because it was the most needed information among inconsistent contents of information. This might also increase awareness and promote behavioural change to support cancer prevention. Mass media, which was the main cancer information source, might be able to provide information about cancer prevention effectively. However, previous studies indicated that mass media tend to focus on cancer treatment and patients rather than on prevention [31-33]. Furthermore, the distinctive characteristics of Japanese mass media coverage are not well understood. Thus, additional research on how cancer information is presented by Japanese mass media is needed.

The current study had some limitations. First, this study was conducted in an Internet setting. Selection bias is a major factor known to limit the generalizability of results in the Internet survey. It occurs because of the non-representative nature of the Internet population and the self-selection of participants [34,35]. However, this study has random selection of participants, an equally distributed gender (men or women) and age group (20–69 years) from a pool of 300,000 people. These may have helped to mitigate bias and ensure greater representativeness in the survey. Second, data are susceptible to responder bias because of self-reported data. Third, the present study used a self-administered questionnaire to examine obtaining information about cancer. Although the questionnaire was adopted from the previous survey, psychometric properties of scales had not evaluated. Therefore, the reliability and validity of the scales were insufficient. Finally, present study was the lack of clarity between active and passive information obtaining behaviours. Furthermore, lack of differentiating between obtaining information for one-self and obtaining information for others was another limitation.

The prevalence of individuals obtaining information about cancer among Japanese adults through internet-based study was not sufficient. The result highlights a need for effective health communication strategies to inform people about cancer. In particular, communication efforts should be targeted towards men and younger people. Additionally, mass media was the most common source of information about cancer, and information was required about prevention as well as screening, symptoms and treatment. The present study would contribute to the development of health communication strategies to providing Japanese people with information about cancer by understanding subgroup with low obtaining information and preferences including information source and content.