Recurrent sick leave and resignation rates among female cancer survivors after return to work: the Japan sickness absence and return to work (J-SAR) study

According to the statistics of the Ministry of Internal Affairs and Communication, Japan (2010), the working age population in Japan includes 81.3 million people; however, it is estimated that it will decrease in size by almost 50% in the next 50 years [1]. Currently, Japan is transitioning to a society where women, senior citizens, and foreigners will be indispensable to the employment market [2]. In many developed countries, the number of cancer patients in the working population is increasing, and the probability that workers will suffer from cancer is also rising [2‐4]. In Japan, these phenomena are caused by the following four factors: the first factor is the increase in the number of senior citizens that are still working. It has been reported that some workers in their 60s develop cancer after becoming temporary workers after their mandatory retirement at 60 years old [1]. The second factor is an increase in the number of working women. In fact, the number of double-income households (in which both the husband and wife work) markedly exceeds the number of households that include full-time housewives [1]. The third factor is the increasing incidence of cancer among females, especially breast cancer, and the younger age of onset of cervical cancer [5]. The fourth factor is that the prognosis of cancer patients has improved due to the development of treatments that place less burden on the body [6].

As cancer survival rates have improved due to recent advances in cancer treatment, more cancer survivors are able to resume their everyday lives and return to work (RTW) during or after treatment [3, 7, 8]. While cancer is more likely to occur among the elderly, breast cancer and uterine cancer are common in people of working age [9].

In February 2016, the “guidelines for the support of therapy and working life in the Japanese workforce” were published by the Japanese Ministry of Health, Labour and Welfare [10]. As a result of the revision of the Cancer Control Act in December 2016, companies in Japan are required to support the reinstatement of employees with cancer [11].

While returning to work would seem to indicate that a cancer survivor has completely recovered from their illness and the adverse effects of treatment, it actually only demonstrates that their ability to perform their job has recovered to a level where they can be reinstated. After returning to work, cancer survivors often encounter difficulties associated with the balance between the demands of treatment and recovery and the requirements of the workplace [12‐14]. Some cancer survivors continue to receive chemotherapy, whereas others suffer from cancer-related fatigue (CrF), pain, functional impairment, and/or psychological distress [15, 16]. Working after returning to work is extremely challenging for cancer patients, especially with regard to physical and mental health [17, 18].

Although a number of studies of cancer survivors have been carried out in Europe and the US, there have not been any workforce-based Japanese cohort studies investigating the frequency of recurrent sick leave or resignations among female cancer survivors that they RTW [15, 19‐22]. It is very important to clarify the work sustainability of female cancer survivors that RTW, as females in their 20s to 40s are more likely to suffer from cancer than their male counterparts [5].

The objective of this study was to investigate the cumulative recurrent sick leave rate and cumulative resignation rate after Japanese female cancer survivors RTW and to analyze predictors of recurrent sick leave, resignation between different cancers. This study is the first cohort study to examine the work sustainability of cancer-affected female employees in Japan.

In total, 223 female employees returned to work after their first period of sick leave due to cancer. The subjects’ characteristics are shown in Table 1. Among these employees, breast cancer was the most common type of cancer (ICD-10, C50; n = 90). The second most common type of cancer was female genital malignancy, which included cancer of the uterus (n = 47) and ovarian cancer (n = 17). The third most common type of cancer was gastric cancer (n = 18), followed by lung cancer (n = 16). The other types of cancer (n = 35) seen among the employees included colon cancer (n = 5) and esophageal cancer (n = 3). The subjects’ mean age on the initial day of their sick leave was 48.2 years old. Just after returning to work, 185 cancer survivors (83.0% of RTW employees) had their work schedules reduced based on OP certificates, and 38 cancer survivors were able to work full-time.

After returning to work, 61 subjects (27.3%) experienced further periods of sick leave (recurrent sick leave) due to medical reasons, which were certified by their physicians. Of these 61 employees, 43 experienced recurrent sick leave due to their original cancer, 4 developed new types of cancer (other cancer), 4 suffered from common mental disorders, and 3 suffered fractures. Twenty-two cancer survivors resigned before reaching retirement age (60 years). Among all cancer survivors, the median duration of the period of work after the subjects initially returned to work was 10.6 years. During the follow-up period, 12 female employees died after the day of RTW. Of the 12 deaths, 9 employees died within the period of recurrent sick leave.

As far as we know, this is the first longitudinal cohort study to investigate the work sustainability of female cancer survivors after they RTW. We found that about 60% of female cancer survivors were still working at 5 years after their RTW, although the work continuance rate differed significantly among different cancer types. In particular, the lung cancer patients exhibited had the lowest work continuance rate. Though there were no statistically significant difference between different cancers, as for recurrent sick leave and resignation, that could be caused by the rather small sample in this study.

The main work-related problems experienced by female cancer survivors after they RTW are as follows: the first is recurrent sick leave due to a physician-certified medical reason (including death). As shown in Fig. 2, we found that recurrent sick leave most commonly occurred in the first year after the cancer survivors returned to work, followed by the second year. Of the female cancer survivors who required recurrent sick leave (n = 61), 25.0, 32.4, and 53.6% required such leave within 6 months, 1 year, and 2 years of their RTW, respectively. The competing risk curve for recurrent sick leave plateaus at 5 years after a cancer survivor returns to work, and hence, is very similar in shape to the Kaplan-Meier curve of recurrent sick leave due to depression produced in a previous study [26].

The second problem experienced by female cancer survivors is having to resign before they reach retirement age (60 years old). In the present study, the cumulative resignation rate was unexpectedly low. The survival curve of the cumulative resignation rate remained below 10% until 4 years after the subjects returned to work. Of all the post-RTW resignations, 17.9, 33.1, 49.0, 56.2, 65.6, and 70.9% had occurred within 6 months, 1 year, 2 years, 3 years, 4 years, and 5 years after the subjects returned to work. Short et al. reported that about 10% of cancer survivors resigned from their jobs within a 4-year period because of cancer-related factors [31]. Stewart et al. reported that about 12.5% of breast cancer survivors quit their jobs before retirement as a result of cancer [32].

Female cancer survivors’ work continuance rates (60.4%) at 5 years after the RTW day were higher than male cancer survivors (48.5%) [27]. We speculated that the probability of more male cancer survivors who had cancer sites of lower work continuance rates (for example, lung cancer, hepatic cancer, pancreatic cancer, esophageal cancer) was higher than female. As for comparing work continuance rates by cancer sites, the female work continuance rates 63.1% of gastric cancer at 5 years after RTW was almost same as male (62.1%). However, the female work continuance rates of lung cancer (31.3%) at 5 years after RTW were higher than male (12.1%). As the 5-year relative survival rates of lung cancer among female, male cancer survivors were 43.2, 27.0%, respectively, the epidemiology of lung cancer tissue types might affect the difference in the work continuance rates between women and men [9] While only 4 employees in the present study took recurrent sick leave due to mental disorders (certified by psychiatrists), cancer survivors often suffer from more severe anxiety and depression than non-cancer survivors [33]. Cancer survivors might fear the recurrence or progression of their disease, which might act as a strong stressor, even years after the initial diagnosis [34]. While employees with cancer struggle to stay in work, raise their children, and live a normal life, the work sustainability of female cancer survivors tends to be lower than that of male cancer survivors [35]. Gudbergsson et al. reported that female cancer survivors experienced more job-related strain than males [36]. In addition, De Boer et al. reported that it took more time for female cancer survivors to recover their work abilities than male cancer survivors [20]. Our study showed that the work continuance rate of female cancer survivors was higher than that of male cancer survivors, while the survival rate of Japanese female cancer survivors was estimated to be higher than that of Japanese male cancer survivors according to the Japan cancer registry [27, 37]. As for the social support provided to cancer survivors with work-related disabilities, it varies from country to country. In the Netherlands, cancer survivors can apply for a work disability benefit after being on sick leave for 2 years, whereas working Japanese cancer survivors are not supported by similar laws or government recommendations, and so the support available depends on the employee’s company [2, 38]. In a study by Bradley et al., the proportion of cancer survivors that underwent a partial RTW was lower than in the present study (80%) [39]. The female cancer survivors in the current study were supported by OP, who encouraged the use of adaptations to facilitate partial RTW because they worked in large companies. We speculate that, more female cancer survivors would be able to continue their work after RTW, if they are supported by various employment support even in small and medium-sized businesses. This study provides useful epidemiological information about RTW support, especially for cancer patients in small and medium-sized enterprises [15]. However, it should always be noted that studies can differ in terms of their design, methodology, and the social circumstances of their subjects [40, 41].

Sixty percent of female cancer survivors were still working at 5 years after they returned to work, although the work continuance rate differed significantly among the various types of cancer. Recurrent sick leave occurred most frequently in the first year after the subjects returned to work, followed by the second year.