DISCUSSION
cancer, breast cancer
CANCER, MAY, BREAST CANCER
In this study, the effects of an environmental approach offering on‐site mammography in workplaces were investigated in 25 supermarket stores in Japan, where the breast cancer screening rate in the previous 2 years was approximately 20% at baseline. On‐site mammography increased the breast cancer screening rate to 53% among participants who had not been screened in the previous year, with an absolute difference between the two groups of 46%. The results suggested that the intervention had a significant effect. In addition, the effect was greater in those who had never been screened and the effect was observed regardless of the characteristics of the participants.Previous studies in workplaces in the United States have reported that on‐site mammography is an effective way to improve the screening rate.Another barrier reduced in our study was inaccessibility. Previous studies have also reported that mobile mammography vans reduced the barrier of screening inaccessibility.In Japan, the breast cancer screening rate increased to 47% in 2019 through various efforts by municipalities, including traditional educational approaches, sending tailored messages, and removing out‐of‐pocket costs by the provision of free coupons.Previous studies have reported that cancer screening rates are lower among populations such as smokers,The provision of mammography in workplaces incurs both the direct costs of screening and indirect costs, such as the human resources involved in arranging mammography and the time away from work to attend the examination (approximately 20 min, including walking to the mammography van, a brief medical interview, clothing removal, and the mammography examination). However, almost all the direct and indirect costs are for conducting the screening rather than educational costs to improve knowledge about screening and to promote health behaviors. Workplace screenings are probably more cost‐saving than employees booking a whole day off work to have a mammogram outside the workplace. At small sites, it may be difficult to recruit sufficient people to attend screenings and to find parking space for a mammography van, which takes approximately as much space as three cars. An environmental approach like that used in the present study may be feasible if several small sites in the neighborhood cooperate or if temporary police permission to use roads is obtained. We think it would be difficult to require all workplaces to cover the cost of screenings, especially small and medium‐sized enterprises and those with many part‐time employees. However, the employment rate of Japanese women in 2021 was approximately 70%,Our study had several limitations. First, the intervention was conducted from May to July 2018, and we asked about breast cancer screening in 2018 as the outcome. We may therefore have included screenings from January to March. However, we believe that this would have had a minimal effect on the results because the 2017 screening rates were similar for both groups, and the effect of the intervention was sufficiently significant. Second, the breast cancer screening rate was evaluated using a self‐administered questionnaire. This may have been subject to recall bias because the breast cancer screening rate in 2016 was smaller than in 2017. Participants' responses about screenings conducted more than 2 years ago may have been unreliable. To address this issue, we stratified results by past screening history, not limited to the previous 2 years. Third, we had to reduce the original 2‐year observation period to 1 year because the health insurance society independently decided to start breast cancer screening in all the supermarket stores once it became evident that so many of their employees wished to receive screenings in the workplace. We therefore focused our discussion on participants who had not been screened in the previous year. Although the study protocol had to be changed, the decision of the health insurance society to start its own initiative because of this trial was an important development. Fourth, despite randomization, there was an imbalance of participant characteristics between the assigned groups. To address the imbalances in age and smoking status, we used multivariable‐adjusted models for the main findings. Fifth, we did not evaluate the between‐group differences in cost‐effectiveness regarding future medical costs or changes in mortality, although the ultimate purpose of cancer screening is to reduce mortality. Sixth, the participants were limited to the employees of a single Japanese retail company. Further research in different fields is warranted to ensure generalizability.Despite these limitations, this was, to the best of our knowledge, the first randomized trial in Japan showing the effect of an environmental approach offering on‐site mammography in the workplace. The results suggest that changing the healthcare system to provide breast cancer screening in the workplace would improve the early detection of breast cancer.