Prognostic impact of interval breast cancer detection in women with pT1a N0M0 breast cancer with HER2-positive status: Results from a multicentre population-based cancer registry study

• Published in: European journal of cancer (1990) Vol. 88; pp. 10 - 20
• Main Authors: Musolino, A., Falcini, F., Sikokis, A., Boggiani, D., Rimanti, A., Pellegrino, B., Silini, E.M., Campanini, N., Barbieri, E., Zamagni, C., Degli Esposti, R., Cortesi, L., Bisagni, G., Cavanna, L., Frassoldati, A., Sgargi, P., Michiara, M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-01-2018; Elsevier Science Ltd
• Subjects: Breast cancer; Cancer; Cancer registry; Confidence; Confidence intervals; Epidermal growth factor; ErbB-2 protein; HER2-positive; Interval cancer; Invasiveness; Monoclonal antibodies; Population studies; Population-based studies; pT1a; Screening; Studies; Survival; Targeted cancer therapy; Trastuzumab; Tumors; Variables; pT1a; Interval cancer; Screening; Breast cancer; Cancer registry; HER2-positive
• ISSN: 0959-8049; 1879-0852
• DOI: 10.1016/j.ejca.2017.10.024

Although human epidermal growth factor receptor 2 (HER2) overexpression is associated with poor prognosis, patients (pts) with pT1a N0M0 breast cancers (BCs) have an excellent outcome across all subtypes. Interval cancers (ICs) have poorer survival than screen-detected (SD) tumours, and an association has been reported between ICs and HER2 overexpression. We aimed to determine, in a general population of pT1a N0M0 BCs with known screening status, whether HER2-positive ICs have a poorer outcome than HER2-positive SD cancers.
We evaluated all incident pT1a N0M0 BCs (n = 874) collected in the Emilia-Romagna region (Italy) from 2003 to 2009 and diagnosed in women aged 50–69. Pts unexposed to screening, with unknown HER2 status and/or treated with adjuvant trastuzumab were excluded from analysis.
Sixty-one percent of the BCs were SD, whereas 19% were ICs. BCs with high histologic grade, hormone receptor–negative or HER2-positive status (odds ratio=1.7; 95% confidence interval [CI]: 1.1–2.7) were more likely ICs. Median follow-up was 115 months. The 10-year invasive disease-free survival (iDFS) for HER2-positive ICs was lower than that for HER2-positive SD cancers: 75.0% (95% CI: 55.5%–94.5%) versus 93.8% (95% CI: 86.5%–100%). An interaction between ICs and HER2-positive status was found for poorer iDFS after adjusting for prognostic variables (HR = 5.3; 95% CI: 1.6–16.7).
IC detection may identify pts with HER2-positive pT1a N0M0 tumours in whom the rate of recurrence justifies consideration for conventional, anti-HER2, adjuvant treatment.
•pT1a N0M0 human epidermal growth factor receptor 2 (HER2)-positive interval cancers have a poorer outcome than HER2-positive screen-detected (SD) cancers.•Consider aggressive adjuvant treatments only in patients with interval-detected tumours.•Avoid overtreatment strategies in small, HER2-positive SD cancers.