br The major strength of this study was the use
The major strength of this study was the use of data from Swedish population-based registers with high completeness, minimizing selection and information bias. Through linkage be-tween different registers we were able to study the underlying causes of absence from work, taking several important factors such as for example disease progression into account. Another important strength included the use of multi-state models, which captures the complexity of the data with multiple, closely related and possibly also recurrent outcomes. Our finding that treatment-related adverse events can cause permanent work loss in women with breast cancer is generalizable also to other countries with high female labor force participation rates, although the observed impact on working life might differ according to legislation and generosity of sickness benefits.
One limitation of the study was uncertainty of the precision of registered diagnoses. Sickness benefits are granted based on the assigned diagnoses, but coding practices may have varied by local routines, between certifying physicians, and calendar periods. So-cial insurance legislation has changed during the study period, which led to a more strict assessment of the entitlement for long-term sick leave and disability pension. It cannot be excluded that these changes also influenced which diagnoses were recorded and accepted on the medical certificate. Additionally, information on the diagnosis was only available for the start of a period with sick leave or disability pension; changes of the original diagnosis were
Hazard ratio with 95% confidence intervals of being granted disability pension attributed to cancer in women of working age diagnosed with breast cancer 2000e2012.
Post-diagnostic cancer metastasis No 1 (Ref.) 1 (Ref.)
Abbreviations: ALND, axillary lymph node dissection; ER, MK-571 receptor; SNB, sentinel node biopsy.
a Model 1: Adjusted for age at diagnosis, calendar year of diagnosis, highest level of education, region, prior sick leave, prior hospitalization for cancer, and all of the post-diagnostic intermediate events (treated as time-varying covariates). b Model 2: Adjusted for the same variables as in Model 1 and tumor characteristics.
c Model 3: Adjusted for the same variables as in Model 1 and tumor and treatment characteristics.
not recorded. It is likely that the influence on absence from work due to causes other than breast cancer has been underestimated since conditions secondary to breast cancer treatment could have been coded as “breast cancer” by the treating physician. We were able to partly address these limitations by using medical diagnoses from other registers. Furthermore, calendar time trends were accounted for by design, and estimates of relative risk are pre-sumable not affected by policy changes over time. Another limita-tion is that we lacked information on work-related risk factors for sick leave and disability pension such as workplace demand and
In conclusion, we found that breast cancer has a significant impact on working life that is not only attributed to disease pro-gression. Women with breast cancer were at increased risk of leaving the labor market because of mental health problems, fa-tigue and pain-related symptoms, lymphedema, cardiovascular, and inflammatory diseases. To limit the consequences of breast
cancer in women of working age, follow-up, support, and rehabil-itation programs must therefore address a wide range of psycho-logical and physical conditions.
Conflicts of interest
Mats Lambe owns Pfizer and AstraZeneca shares. All other au-thors declare no competing interests.
Preliminary results were presented at the Association of Nordic Cancer Registries (ANCR) Symposium 2018 in Hella, Iceland June 12e14, 2018.
Appendix A. Supplementary data
This project was supported by grants from the Swedish Medical Research Council (521-2012-3047), the Swedish Cancer Society (14e0324), and the Swedish Breast Cancer Association. We also thank the Breast Cancer Quality Register steering groups in Stock- € holm, Uppsala-Orebro and the Northern region for providing data for anticodon study.
Role of the funding source
The funding organizations had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
 Kvillemo P, Mittendorfer-Rutz E, Branstrom R, Nilsson K, Alexanderson K. Sickness absence and disability pension after breast cancer diagnosis: a 5-year nationwide cohort study. J Clin Oncol 2017;35(18):2044e52.