Cancer Outcomes in DCIS Patients Without Locoregional Treatment

Abstract

Background: The vast majority of women diagnosed with ductal carcinoma in situ (DCIS) undergo treatment. Therefore, the risks of invasive progression and competing death in the absence of locoregional therapy are uncertain.

Methods: We performed survival analyses of patient-level data from DCIS patients who did not receive definitive surgery or radiation therapy as recorded in the US National Cancer Institute's Surveillance, Epidemiology, and End Results program (1992-2014). Kaplan-Meier curves were used to estimate the net risk of subsequent ipsilateral invasive cancer. The cumulative incidences of ipsilateral invasive cancer, contralateral breast cancer, and death were estimated using competing risk methods.

Results: A total of 1286 DCIS patients who did not undergo locoregional therapy were identified. Median age at diagnosis was 60 years (inter-quartile range = 51-74 years), with median follow-up of 5.5 years (inter-quartile range = 2.3-10.6 years). Among patients with tumor grade I/II (n = 547), the 10-year net risk of ipsilateral invasive breast cancer was 12.2% (95% confidence interval [CI] = 8.6% to 17.1%) compared with 17.6% (95% CI = 12.1% to 25.2%) among patients with tumor grade III (n = 244) and 10.1% (95% CI = 7.4% to 13.8%) among patients with unknown grade (n = 495). Among all patients, the 10-year cumulative incidences of ipsilateral invasive cancer, contralateral breast cancer, and all-cause mortality were 10.5% (95% CI = 8.5% to 12.4%), 3.9% (95% CI = 2.6% to 5.2%), and 24.1% (95% CI = 21.2% to 26.9%), respectively.

Conclusion: Despite limited data, our findings suggest that DCIS patients without locoregional treatment have a limited risk of invasive progression. Although the cohort is not representative of the general population of patients diagnosed with DCIS, the findings suggest that there may be overtreatment, especially among older patients and patients with elevated comorbidities.

Figure 1.

US National Cancer Institute’s Surveillance, Epidemiology, and End Results program (1992–2014): selection of ductal carcinoma in situ patients without locoregional treatment.

Figure 2.

Net risk of ipsilateral invasive breast cancer (iIBC) in patients without locoregional treatment, based on US National Cancer Institute’s Surveillance, Epidemiology, and End Results program (SEER) (1992–2014). The cumulative net risk of iIBC in the SEER no-treatment cohort is shown for all cases combined (A) and stratified by tumor grade (B), estrogen receptor (ER) status (C), tumor size (D), and age at diagnosis (E). The net risk (up to 10 years only) of iIBC in “low-risk” patients (40 years or older at diagnosis, nonhigh-grade, and ER and/or progesterone receptor-positive ductal carcinoma in situ) is shown in (F). The number of patients at risk is shown beneath the figures. Subgroup comparisons (excluding unknowns) were performed using a log-rank test.

Figure 3.

Competing risks in ductal carcinoma in situ (DCIS) patients, based on US National Cancer Institute’s Surveillance, Epidemiology, and End Results program (SEER) (1992–2014). The cumulative incidence of competing events (ipsilateral invasive breast cancer, any contralateral breast cancer, and competing death) in the study cohort is shown for all cases combined (A) and for “low-risk” patients (40 years or older at diagnosis, nonhigh-grade, and estrogen receptor and/or progesterone receptor-positive DCIS) (B). Similarly, the cumulative incidence of competing events among SEER who underwent guideline-concordant care is shown for all cases combined (C) and for “low-risk” patients (D). Please note the difference in follow-up shown: 20 years in A and C, and 10 years in B and D.

Figure 4.

Net risk of ipsilateral invasive breast cancer (iIBC) based on retrospective cohort studies of ductal carcinoma in situ patients without locoregional treatment. The cumulative net risk of iIBC in the pooled retrospective cohort studies is shown for all cases combined (A) and stratified by tumor grade (B) and age at diagnosis (C). The number of patients at risk is shown beneath the figures. Subgroup comparisons were performed using a log-rank test.