Background:
It has been 10 years since a population-based mammography screening was implemented in Japan. Publicly funded mammography and breast examination are performed every two years on women who are over 40 years old. It is important that the subjects understand the benefits of breast cancer screening in terms of a reduced mortality from breast cancer; however, they must also be aware of the potential disadvantages, such as false-positive diagnoses and over diagnosis. It is unclear how well the Japanese people understand the benefits and harms of breast cancer screening. This study assessed the opinions of participants in Akita, Japan, asking them about the benefits and harms attributable to breast cancer screening. Their answers were compared with those given by a group of registered nurses, who had been asked the same questions.
Methods:
This study was carried out from August to December 2014 in Akita, Japan. A questionnaire survey, including questions on the expected benefits and harms of breast cancer screening was devised and given to women undergoing screening mammography and breast examination. The same survey was given to nurses working in eight hospitals in the Akita Kouseiren Hospital group.
Results:
The questionnaire survey was given to 1649 participants aged 29–96 years and 1905 registered nurses (including 89 men) aged 20–69 years. All the members of the first group experienced breast cancer screening, but 42% of the registered nurses had no screening experience. The questionnaire was returned by 1552 people (94.1%) and 1710 people (89.8%), respectively. There were many misunderstandings found in the answers to the questions. The common misconceptions were as follows: screening prevents or reduces the risk of development of breast cancer (86% of participants, 62% of registered nurses); screening reduces the mortality from breast cancer by more than 50% (69% of participants, 60% of registered nurses); and 10 years of regular screening for 50-year-old women will prevent 10 or more breast cancer deaths per 1000 women (62% of participants, 61% of registered nurses). However, there were some correct answers; approximately half of the people studied (46% of participants, 57% of registered nurses) knew that detecting a cancer early by screening did not always reduce mortality or lengthen life.
Conclusion:
In Japan, most people overestimated the benefit that can be expected from breast cancer screening and the number of women who would benefit was not well understood. These misunderstandings were seen in the group of registered nurses as well as in the participants. So far, breast cancer screening has been publicized with only positive messages, for example, "the earlier the better" and "the smaller the better." Henceforth, screening should be publicized with more balanced messages, including figures for how many women will benefit and how many will be harmed. Individuals should then be able to use that information to make an informed choice about whether or not to undergo breast cancer screening.
Citation Format: Shimada T, Takahashi M, Tsukisawa K, Shimizu Y, Tanaka M, Saito N, Takahashi K, Ishikawa N, Hashimoto M, Kinouchi K, Fujiwara M, Sato T. Knowledge of the potential benefits and harms of breast cancer screening: A survey of participants and nurses. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-02-10.
