Age-specific survival after breast conservation versus mastectomy for ductal carcinoma in situ of the breast

de Boniface, J., Szulkin, R., Karlsson, P., & Johansson, A. L. (2026). Age-specific survival after breast conservation versus mastectomy for ductal carcinoma in situ of the breast. Breast Cancer Research and Treatment, 220(1), 10.

Breast-conserving surgery (BCS) for DCIS is associated with higher local recurrence rates than mastectomy, although previous studies have found no difference in breast cancer-specific mortality (Mannu et al., 2024). Evidence from invasive breast cancer suggests that breast conservation may offer survival advantages over mastectomy (de Boniface et al., 2021), particularly in older women, but whether this applies to DCIS remains unclear. This Swedish population-based cohort study therefore compared age-specific survival (in three groups: <60, 60–69 and ≥70 years) and local recurrence following BCS with radiotherapy (BCS+RT), mastectomy without radiotherapy (Mx−RT), and BCS without radiotherapy (BCS−RT) in women treated for DCIS between 2008 and 2019.

A total of 7,165 women met the eligibility criteria, of whom 1,387 (19.4%) were aged ≥70 years. Treatment consisted of BCS+RT in 3,821 (53.3%), BCS−RT in 963 (13.4%) and Mx−RT in 2,381 (33.2%). Among women aged ≥70 years, BCS−RT was the most common treatment, followed by Mx−RT and BCS+RT. Multivariable Cox regression models were adjusted for demographic, socioeconomic, tumour-related and comorbidity factors.

The 10-year risk of local recurrence was relatively low at 7.2%, with higher recurrence following BCS+RT than Mx−RT, particularly in women aged ≥70 years. However, Mx−RT was associated with higher overall mortality than BCS+RT in the complete-case analysis (HR 2.10; 95% CI 1.20–3.67), although this association was not maintained following multiple imputation. In women aged ≥70 years, increased mortality following Mx−RT was consistent across both analyses (complete-case HR 2.48; 95% CI 1.09–5.62). Interestingly, BCS−RT was also associated with higher overall mortality than BCS+RT.

These findings should be interpreted cautiously given the potential for residual confounding and selection bias. Although the models adjusted for numerous confounders, unmeasured factors such as surgical margin status, smoking, obesity and postoperative complications may have influenced treatment selection and survival outcomes. Differences in socioeconomic status and comorbidity may also have contributed.

The low 10-year recurrence risk (7.2%) adds to evidence that local recurrence following DCIS has declined over time, mirroring trends in invasive breast cancer despite the absence of improved systemic therapies for DCIS. The authors conclude that although BCS+RT is associated with higher local recurrence than mastectomy, it may offer an overall survival advantage, particularly in older women. These findings support the safety of the increasing use of breast-conserving surgery for DCIS.

References

de Boniface, J., Szulkin, R., & Johansson, A. L. (2021). Survival after breast conservation vs mastectomy adjusted for comorbidity and socioeconomic status: a Swedish national 6-year follow-up of 48 986 women. JAMA surgery, 156(7), 628-637.

Mannu, G.S., et al. Invasive breast cancer and breast cancer death after non-screen detected ductal carcinoma in situ from 1990 to 2018 in England: population based cohort study. BMJ 384, e075498 (2024).

Summary author: Mr Thomas Hubbard, Consultant Oncoplastic Breast Surgeon & Honorary Clinical Senior Lecturer, Exeter