Potential gain in life years for Swedish women with breast cancer if stage and survival differences between education groups could be eliminated - three what-if scenarios

Many studies have found evidence of socioeconomic differences in breast cancer survival. This study aimed to quantify the impact of removing differences in stage distribution and stage-specific relative survival between education groups in Swedish women with breast cancer. Using information from a breast cancer research database, the study population contained 62 121 women diagnosed with breast cancer in three healthcare regions of Sweden from 1992 to 2012. The loss in expectation of life and life years lost due to breast cancer were estimated using flexible parametric relative survival models by education group and age at diagnosis. The potential gain in life years and postponable deaths were calculated by applying the 1) stage distribution, 2) stage-specific relative survival, and 3) both stage distribution and stage-specific relative survival of the high education group to the low and medium education groups. For a cohort of around 3500 women diagnosed with breast cancer residing in three Swedish healthcare regions in a typical calendar year, we estimated that removing stage differences would postpone an additional 25 deaths at five years after diagnosis, and result in a gain of approximately 573 life years. Alternatively, if stage-specific breast cancer survival could be equated, approximately 692 life years could be saved and an additional 26 deaths could be postponed five years after diagnosis. Results such as these can help guide decisions on interventions intended to minimise socioeconomic differences in breast cancer outcomes.