DCIS Surgery: Survival Associations in Women 70 and Older

Key Takeaways

• Swedish women with DCIS had high estimated 10-year breast cancer-specific survival across the cohort.
• Among women aged 70 or older, mastectomy without RT was associated with higher adjusted overall mortality than BCS plus RT in both analyses.
• Across ages, the higher adjusted overall mortality associated with mastectomy without RT was statistically significant in complete cases but not after multiple imputation.
• BCS without RT was associated with higher adjusted overall mortality than BCS plus RT in both analyses.
• Relative to BCS plus RT, local recurrence was lower after mastectomy without RT and higher after BCS without RT.

For women with ductal carcinoma in situ (DCIS), uncertainty about surgery and radiotherapy choices is especially relevant at older ages. Survival and local recurrence represent distinct concerns in weighing breast conservation against mastectomy. Investigators examined these outcomes in a population-based Swedish comparison.

Investigators identified 7,165 women with DCIS in the Breast Cancer Database Sweden (BCBaSe 3.0), forming a population-based Swedish cohort. The treatment groups were breast-conserving surgery (BCS) plus radiotherapy (RT), mastectomy without RT, and BCS without RT. They assessed overall survival, breast cancer-specific survival, and local recurrence across three age groups. Adjusted comparisons used BCS plus RT as the reference and accounted for patient and tumor factors, including socioeconomic status and comorbidity. The investigators reported complete-case and multiple-imputation analyses; treatment was not randomly assigned.

Estimated 10-year overall survival across the cohort was 90.4% (95% confidence interval (CI), 89.3–91.5), while breast cancer-specific survival was 98.8% (95% CI, 98.3–99.2). Across all ages, adjusted overall mortality after mastectomy without RT was significantly higher than after BCS plus RT in the complete-case analysis, but not after multiple imputation. Adjusted overall mortality after BCS without RT was higher than after BCS plus RT in both analyses.

For women aged 70 or older, mastectomy without RT was associated with higher adjusted overall mortality than BCS plus RT in the complete-case analysis (hazard ratio (HR) 2.48; 95% CI, 1.09–5.62) and the multiple-imputation analysis (HR 1.89; 95% CI, 1.23–2.90). These associations concern mortality from any cause, not specifically from breast cancer. Local recurrence across the cohort was uncommon; compared with BCS plus RT, adjusted recurrence was lower after mastectomy without RT and higher after BCS without RT.

The investigators acknowledged possible treatment-selection bias: differences among women receiving each treatment could contribute to the observed survival associations, which do not establish a causal benefit. The all-age mastectomy association with higher overall mortality did not remain statistically significant after multiple imputation. Overall mortality includes deaths from any cause, whereas breast cancer-specific survival concerns breast cancer deaths; the survival findings do not establish a treatment-specific difference in the latter.

According to the investigators, BCS plus RT appears safe for DCIS and may be associated with favorable overall survival among older women, although selection bias limits interpretation. Mastectomy without RT was associated with less local recurrence than BCS plus RT.

Clinician Questions

Are the 10-year DCIS survival and recurrence estimates specific to each surgery and radiotherapy option?

The estimated 10-year overall survival, breast cancer-specific survival, and local-recurrence probabilities for women with ductal carcinoma in situ (DCIS) in the Swedish cohort describe the whole cohort. They are not absolute rates for breast-conserving surgery with or without radiotherapy or mastectomy without radiotherapy; comparisons among those options were adjusted associations.

Was local recurrence after breast-conserving surgery without radiotherapy particularly apparent in older women with DCIS?

Swedish investigators described the higher local-recurrence association after breast-conserving surgery without radiotherapy, compared with breast-conserving surgery plus radiotherapy, as especially apparent among women with ductal carcinoma in situ (DCIS) aged 70 or older.

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