179PD - Tumor size and overall survival in a cohort of young (≤40 years), nodenegative, systemically untreated breast cancer patients; by the PARADIGM study group

Abstract

BackgroundIn the 1990s, the use of adjuvant systemic therapy was based on nodal involvement but not on tumor size, as was recommended in the Dutch breast cancer guidelines. Tumor size is an important prognostic variable in breast cancer, although this may not hold true for all molecular subtypes or patient ages. Here, we studied the prognostic value of tumor size for young (≤40 years at diagnosis), systemically untreated, node-negative (N0), breast cancer patients, and assessed whether for any given T-stage survival exceeds 90% at 20 years. MethodsAll female, breast cancer patients, ≤40 years at time of diagnosis (between 1989 and 2000), were selected from the Netherlands Cancer Registry. All lymph node-positive and systemically treated patients were excluded, resulting in a cohort of 2302 women. Clinico-pathological and follow-up data were collected from national databases, patient records, and the original pathology reports. Multivariate cox regression for overall survival was performed using T-stage (TNM 8.0), molecular subtype, and tumor grade (according to Nottingham Histologic Score) as covariates. ResultsSurvival rates at 20-years are shown in Table. Median follow-up was 17 years. Only 1% had a T3 tumor and these patients were excluded from analysis. The 20-yr OS for the 96 (4%) T1a tumors was 81% (not shown). Women with T2 tumors had a significantly lower OS compared to women with T1a (HR 1.9 P=0.024), T1b (HR 1.7 P=> 0.001) and T1c tumors (HR 1.31 P=0.002), adjusted for tumor grade and molecular subtype. No OS data is shown for subgroups with less than 35 patients.Table179PD Overall survival (OS; %) at 20 years by T-stage, molecular subtype and tumor grade (Gr)TableT1bT1cT2AllnOSnOSnOSnOS3597311146961160230268ER+HER2-Gr 1+2Gr 317282464771655697373436813055834926954All79725569ER-HER2-Gr 1+2Gr 36-31-27-706531-205731586641768All61716368HER2+Gr 1+2Gr 331-745436541595722-8153546116956All70545758 ConclusionsT-stage is associated with OS in this patient group. At 20 years follow-up, we found no T-stage with OS rates >90% in N0, systemically untreated patients, meaning that patients regardless of T-stage may benefit from some form of systemic treatment. Legal entity responsible for the studyThe PARADIGM study group. FundingThe Netherlands Organization for Health Research and Development (ZonMW); A Sister’s Hope; De Vrienden van UMC Utrecht. DisclosureS.C. Linn: Research grant / Funding (self): Amgen; Research grant / Funding (self), unrestricted research grant SUBITO study (NCT02810743): Eurocept-pharmaceuticals; Research grant / Funding (institution), research grant NCT02810743 & olaparib;fulvestrant NCT00738777;advisory board olaparib breast cancer: AstraZeneca; Advisory / Consultancy, Research grant / Funding (institution): Roche; Research grant / Funding (institution), unrestricted research grant for NCT02285179 and study drug (taselisib): Genentech; Advisory / Consultancy, Member of the Scientific Advisory Board of Cergentis (unpaid): Cergentis; Advisory / Consultancy, scientific advisory board for Watson for Oncology (paid to institution): IBM; Research grant / Funding (institution), unrestricted research grant and study drug NCT03283384; research support biomarker study NCT02109913: Novartis; Advisory / Consultancy, Research grant / Funding (institution), scientific advisory board palbociclib; TEAM 2b through unrestricted research grant from Pfizer: Pfizer; Research grant / Funding (institution), Unrestricted research grant paid to institution for ABC study and study drug: Tesaro; Honoraria (institution), Fee for teaching paid to institution: Bayer. All other authors have declared no conflicts of interest.