Combining method of detection and 70-gene signature for enhanced prognostication of breast cancer

Purpose Studies have shown that screen detection by national screening programs is independently associated with better prognosis of breast cancer. The aim of this study is to evaluate the association between tumor biology according to the 70-gene signature (70-GS) and survival of patients with screen-detected and interval breast cancers. Methods All Dutch breast cancer patients enrolled in the MINDACT trial (EORTC-10041/BIG3-04) accrued 2007–2011, who participated in the national screening program (biennial screening, ages 50–75) were included ( n = 1102). Distant Metastasis-Free Interval (DMFI) was evaluated according to the 70-GS for patients with screen-detected ( n = 754) and interval cancers ( n = 348). Results Patients with screen-detected cancers had 8-year DMFI rates of 98.2% for 70-GS ultralow-, 94.6% for low-, and 93.8% for high-risk tumors ( p = 0.4). For interval cancers, there was a significantly lower 8-year DMFI rate for patients with 70-GS high-risk tumors (85.2%) compared to low- (92.2%) and ultralow-risk tumors (97.4%, p = 0.0023). Among patients with 70-GS high-risk tumors, a significant difference in 8-year DMFI rate was observed between interval (85.2%, n = 166) versus screen-detected cancers (93.8%, n = 238; p = 0.002) with a HR of 2.3 (95%CI 1.2–4.4, p = 0.010) adjusted for clinical-pathological characteristics and adjuvant systemic treatment. Conclusion Among patients with 70-GS high-risk tumors, a significant difference in DMFI was observed between screen-detected and interval cancers, suggesting that method of detection is an additional prognostic factor in this subgroup and should be taken into account when deciding on adjuvant treatment strategies.