title: Comparison of 18F-FDG PET/CT for Systemic Staging of Newly Diagnosed Invasive Lobular Carcinoma Versus Invasive Ductal Carcinoma.
abstract: Although guidelines such as those of the National Comprehensive Cancer Network consider (18)F-FDG PET/CT for systemic staging of newly diagnosed stage III breast cancer patients, factors in addition to stage may influence the utility of PET/CT. Because invasive lobular carcinoma (ILC) is less conspicuous than invasive ductal carcinoma (IDC) on (18)F-FDG PET, we hypothesized that tumor histology may be one such factor. We evaluated PET/CT systemic staging of patients newly diagnosed with ILC compared with IDC.
  
  
  METHODS
  In this Institutional Review Board-approved retrospective study, our Hospital Information System was screened for ILC patients who underwent PET/CT in 2006-2013 before systemic or radiation therapy. Initial stage was determined from examination, mammography, ultrasound, MR, or surgery. PET/CT was performed to identify unsuspected distant metastases. A sequential cohort of stage III IDC patients was evaluated for comparison. Upstaging rates were compared using the Pearson χ(2) test.
  
  
  RESULTS
  The study criteria were fulfilled by 146 ILC patients. PET/CT revealed unsuspected distant metastases in 12 (8%): 0 of 8 with initial stage I, 2 of 50 (4%) stage II, and 10 of 88 (11%) stage III. Upstaging to IV by PET/CT was confirmed by biopsy in all cases. Three of 12 upstaged patients were upstaged only by the CT component of the PET/CT, as the metastases were not (18)F-FDG-avid. In the comparison stage III IDC cohort, 22% (20/89) of patients were upstaged to IV by PET/CT. All 20 demonstrated (18)F-FDG-avid metastases. The relative risk of PET/CT revealing unsuspected distant metastases in stage III IDC patients was 1.98 times (95% confidence interval, 0.98-3.98) that of stage III ILC patients (P = 0.049). For (18)F-FDG-avid metastases, the relative risk of PET/CT revealing unsuspected (18)F-FDG-avid distant metastases in stage III IDC patients was 2.82 times (95% confidence interval, 1.26-6.34) that of stage III ILC patients (P = 0.007).
  
  
  CONCLUSIONS
  (18)F-FDG PET/CT was more likely to reveal unsuspected distant metastases in stage III IDC patients than in stage III ILC patients. In addition, some ILC patients were upstaged by non-(18)F-FDG-avid lesions visible only on the CT images. Overall, the impact of PET/CT on systemic staging may be lower for ILC patients than for IDC patients.
authors: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York Department of Radiology, Weill Cornell Medical College, New York, New York.
authors: Molly P
authors: MP
authors: Hogan
authors: Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York.
authors: Debra A
authors: DA
authors: Goldman
authors: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York Department of Radiology, Weill Cornell Medical College, New York, New York.
authors: Brittany
authors: B
authors: Dashevsky
authors: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York.
authors: Christopher C
authors: CC
authors: Riedl
authors: Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York.
authors: Mithat
authors: M
authors: Gönen
authors: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York Department of Radiology, Weill Cornell Medical College, New York, New York.
authors: Joseph R
authors: JR
authors: Osborne
authors: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York Department of Radiology, Weill Cornell Medical College, New York, New York.
authors: Maxine
authors: M
authors: Jochelson
authors: Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York; and.
authors: Clifford
authors: C
authors: Hudis
authors: Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, New York.
authors: Monica
authors: M
authors: Morrow
authors: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York Department of Radiology, Weill Cornell Medical College, New York, New York ulanerg@mskcc.org.
authors: Gary A
authors: GA
authors: Ulaner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001842:Bone and Bones / Q000000981:diagnostic imaging; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D018270:Carcinoma, Ductal, Breast / Q000000981:diagnostic imaging*; D018275:Carcinoma, Lobular / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging; D009367:Neoplasm Staging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011859:Radiography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG; PET/CT; breast cancer; ductal; lobular; staging