Objectives Ductal carcinoma in situ (DCIS) is a localized neoplastic lesion of the breast that can increase the risk of developing invasive breast cancer (IBC). Less than half of screen-detected DCIS progresses to IBC if left untreated. In other words, more than half of screen-detected DCIS are cases of overdiagnosis. Applying these numbers to a Danish context, about 1 per 2000 women who participates in the national mammography screening program each year are overdiagnosed with DCIS. Qualitative research reports that women consider the diagnosis equally life-threatening as IBC. We aimed to quantitatively compare the psychosocial consequences of screen-detected DCIS and IBC, and to examine changes over time.

Method We conducted repeated surveys between 2004 and 2018 among a cohort of Danish women who underwent mammography screening. We measured psychosocial consequences with the Consequences Of Screening – Breast Cancer (COS-BC); a condition-specific questionnaire with high content validity and adequate psychometric properties encompassing 14 psychosocial dimensions. We assessed outcomes at six-time points: baseline, 1, 6, 18, 36 months, and 14 years after the screening. We used weighted linear models with generalized estimating equations to compare responses.

Results Out of 1309 women, 170 were diagnosed with breast cancer (13.0%): 23 were diagnosed with DCIS (13.5%) and 147 with IBC (86.5%). These proportions are similar to National cancer statistics. From baseline to six months after diagnosis, the groups were not significantly different. This indicates that initially, women with DCIS and IBC were equally psychosocially affected by their diagnosis. However, at 18 months, the groups significantly differed on seven out of 14 scales and women with IBC were generally more affected than those with DCIS. Yet, in some domains, it was the other way around. The differences between groups subsided after 36 months. At 14 years, the groups were not significantly different except for three scales where women with IBC were more affected. However, women with IBC rated their overall health significantly better than women with DCIS.

Conclusions Our study found that women with DCIS and IBC reported similar levels of psychosocial consequences over 14 years. This affirms the findings of qualitative studies. Renaming DCIS to remove the nomenclature for cancer may help reduce the psychosocial burden of the diagnosis and encourage women to make better decisions in accordance with their values and preferences, supported by best available evidence. This may also support health professionals and women choose more conservative management options to avoid overtreatment.