Background: Physicians have an important role in patients’ sickness absence (SA) process,and many initiatives have been taken to influence their sickness certification practice. Manyphysicians experience sickness certification as a problematic task. This also applies tooncologists, a group in which a larger proportion has sickness certification tasks more oftencompared to physicians with other specialties. Experiences of encounters with healthcareprofessionals is one factor that has been shown to be of importance regarding SA and abilityto return to work (RTW) among sickness absentees in general. Breast cancer (BC) is the mostcommon cancer among women of working age, however, knowledge about their experiencesof encounters with healthcare professionals regarding SA and work is scarce.Aim: To increase the knowledge about healthcare professionals’ work with SA, how womenwith BC experience encounters with healthcare professionals, and possible associations withSA and RTW.Method: In study I-III, data from three different Swedish surveys were analyzed. Study I: 342oncologists who had sickness certification consultations were included. Study II: A cohort of690 women in Stockholm, who had had surgery for primary BC, and were aged 24-63 yearswere included. Study III: A random sample of 6197 women in Sweden, aged 19-65 years, andon SA since 4-8 months were included. Of those, 187 were on SA due to BC. In study I-III,descriptive statistics were calculated, and logistic regression with odds ratios (OR) with 95%confidence intervals (CI) were used for analyses of associations. Study IV: A systematicliterature review of interventions regarding physicians’ sickness certification practices. Metaanalyseswere performed to produce summarized relative risk estimates with 95% CI fromthe data pooled using random effect models.Results: Study I: A majority of the oncologists had consultations involving sicknesscertification weekly and one fifth experienced such consultations as problematic at least oncea week. Associations were found between oncologists stating not having enoughorganizational resources for work with such tasks and experiencing different aspects ofsickness certification as problematic. Study II: A majority of the women with BC hadexperienced encounters regarding work with healthcare. An association was found bothbetween women having experienced advice and support regarding work and having beenencouraged to work and having less SA, as well as between to have been encouraged to be onSA and having more SA. The latter was partly explained by disease and treatment factors.Study III: Positive encounters with healthcare professionals in connection to SA wereexperienced by almost all the women on SA, both women with BC and with other SAdiagnoses. About half of the women stated that positive encounters promoted their ability toRTW, slightly fewer among women with BC. Four specific types of encounters; “allowed meto take own responsibility”, “encouraged me to carry through my own solutions”, “madereasonably high demands”, and “sided with me/stood on my side” were also experienced to alesser extent by women with BC. Study IV: Nine intervention studies were included. Theeffect measures varied considerably. Significant intervention effects in intended directionwere found in four of the nine interventions, in two interventions unintended effects werefound. The meta-analyses indicated a summarized effect on any RTW (first, partial or full)among the patients.Conclusion: Although oncologists often had sickness certification tasks, such tasks wereseldom experienced as problematic. However, lack of resources for sickness certificationtasks was associated with experiencing such tasks as problematic. Most of the women withBC had experienced encounters from healthcare professionals regarding work and SA theyear after the surgery. Most of the women, both on SA due to BC or due to other diagnoses,had experienced positive encounters, and that such encounters promoted being able to RTW.The results indicate that physicians’ sickness certification practice can be influenced byinterventions.