Abstract
Over 97% of individuals diagnosed with ductal carcinoma in situ (DCIS) will choose to receive guideline concordant care (GCC), which was originally designed to treat invasive cancers and is associated with treatment related morbidity. An alternative to GCC is active surveillance (AS) where therapy is delayed until medically necessary. Differences in mortality risk between the two approaches in women age 65+ are analyzed in this study. SEER and Medicare information on treatment during the first year after diagnosis was used to identify three cohorts based on treatment type and timing: GCC (N = 21,772; immediate consent for treatment), AS1 (N = 431; delayed treatment within 365 days), and AS2 (N = 205; no treatment/ongoing AS). A propensity score-based approach provided pseudorandomization between GCC and AS groups and survival was then compared. Strong influence of comorbidities on the treatment received was observed for all age-groups, with the greatest burden observed in the AS2 group. All-cause and breast-cancer-specific mortality hazard ratios (HR) for AS1 were not statistically different from the GCC group; AS2 was associated with notably higher risk for both all-cause (HR:3.54; CI:3.29, 3.82) and breast-cancer-specific (HR:10.73; CI:8.63,13.35) mortality. Cumulative mortality was substantially higher from other causes than from breast cancer, regardless of treatment group. Women managed with AS for DCIS had higher all-cause and breast-cancer-specific mortality. This effect declined after accounting for baseline comorbidities. Delays of up to 12 months in initiation of GCC did not underperform immediate surgery.