391P - Stealth breast cancer on ring-type dedicated breast PET (391P)

Date 18 November 2017
Event ESMO Asia 2017 Congress
Session Poster lunch
Topics Breast Cancer
Imaging, Diagnosis and Staging
Presenter Shinsuke Sasada
Citation Annals of Oncology (2017) 28 (suppl_10): x117-x118. 10.1093/annonc/mdx672
Authors S. Sasada, N. Masumoto, N. Goda, K. Kajitani, A. Emi, R. Haruta, T. Kadoya, T. Kataoka, M. Okada
  • Breast Surgery, Hiroshima University Hospital, 734-8551 - Hiroshima/JP

Abstract

Background

Dedicated breast PET (DbPET) is a high-resolution molecular breast imaging method that detects subcentimeter breast cancers. However, it is unclear why some breast cancers are invisible to DbPET using 18F-fluorodeoxyglucose (FDG).

Methods

A total of 265 patients (288 tumors) underwent ring-type DbPET and contrast-enhanced magnetic resonance imaging (MRI) in a prone position, between January 2016 and May 2017. Environmental and biological factors behind invisibility to DbPET were assessed. The distance between the shallowest part of breast tumor and the front end of the pectoralis major muscle was taken as the tumor to chest wall distance on MRI.

Results

Twenty four tumors (8.3%) were not visualized by DbPET. Among 44 noninvasive and 15 microinvasive carcinomas, 54 tumors (91.5%) were detected. The tumor to chest wall distance for invisible tumors was shorter than that of the visible tumors (23.0 ± 18.1 mm vs 38.5 ± 21.1 mm, P< 0.001), whereas the cutoff for predicting invisibility was 15 mm. According to univariate analysis, medial location (A/B portions), small size (≤10mm), proximity to chest wall (≤15mm), and low-grade tumors were the factors behind the invisibility. Multivariate analysis suggested that proximity to chest wall and low-grade tumors were independent predicting factors for stealth cancers. Among 24 stealth cancers, 15 tumors were proximity to chest wall, suggesting that they were outside or at the edge of field of view (FOV), and 7 were low-grade tumors, suggesting insignificant FDG uptake.Table: 391P

Univariate and multivariate analysis of predicting invisibility on DbPET

FactorUnivariate analusisMultivariate analysis
Odds ratio (95% CI)POdds ratio (95% CI)P
Medial location of tumor2.80 (1.20–6.56)0.0181.85 (0.70–4.86)0.220
Tumor size ≤10 mm2.41 (1.03–5.63)0.0421.89 (0.70–5.08)0.210
Distance from chest wall ≤15 mm14.0 (5.63–35.1)< 0.00112.1 (4.63–31.6)< 0.001
Nuclea grade 1–23.33 (1.11–10.0)0.0321.98 (1.01–3.89)0.047

Conclusions

Tumors positioned near the chest wall can be a blind spot for DbPET. The factors behind invisible breast cancers are classified into two types; outside or at the edge of FOV location and insignificant FDG uptake.

Clinical trial identification

Legal entity responsible for the study

Hiroshima University

Funding

None

Disclosure

All authors have declared no conflicts of interest.