title: Microinvasive breast cancer: pathological parameters, cancer subtypes distribution, and correlation with axillary lymph nodes invasion. Results of a large single-institution series.
abstract: BACKGROUND
  Microinvasive breast cancer is a rare entity in which an invasive component not exceeding 1 mm is found, mostly in a ductal carcinoma in situ setting. Its diagnosis can be difficult and must rely upon immunohistochemistry markers. Many studies have analyzed pathological characteristics of this cancer to delineate its biological profile and possibly identify risk factors of axillary lymph nodes infiltration, which might be present and therefore clinically relevant. Starting from a relative large number of cases we aimed to analyze pathological data, cancer subtypes distribution, and their correlation to nodal metastasis, comparing our results to the existing recent literature.
  
  
  METHODS
  All cases of microinvasive breast cancer were retrieved from institutional database from 1992 to 2014. Pathological parameters were analyzed for entire cohort. Moreover, cases submitted to standardized sentinel node biopsy in a restricted period, 2000-2014, were selected to correlate pathology and cancer subtype to axillary lymph nodes status.
  
  
  RESULTS
  174 cases (1.4 % of operated breast cancers) were evaluated in the larger period, 1992-2014. Neither specific pathological parameters were expressed nor a peculiar cancer subtype was represented. 126 cases were selected for axillary staging analysis. Eighteen cases (14.3 %) had lymph nodes metastasis, 10 ITCs (7.9 %), 3 micrometastases (2.4 %), and 5 macrometastases (4 %). An associated intraductal component of carcinoma over 20 mm in maximum dimension resulted significant at multivariate analysis, but only if including ITCs, while this risk factor was not reproduced for micro- and macrometastases only.
  
  
  CONCLUSIONS
  Microinvasive breast cancer does not seem to have specific pathological and biological traits. An associated intraductal component of carcinoma >20 mm in size is a specific risk factor for ITCs nodal metastasis. Its clinical significance is anyway limited and therefore sentinel node biopsy should be performed case by case and not routinely.
authors.affiliation: Breast Unit Surgery, Oncology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Orzalesi
authors.affiliation: Breast Unit Surgery, Oncology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Donato
authors.initials: D
authors.lastname: Casella
authors.affiliation: Breast Unit Surgery, Oncology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Criscenti
authors.affiliation: Breast Unit Surgery, Oncology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Ulpiana
authors.initials: U
authors.lastname: Gjondedaj
authors.affiliation: Pathology, Department of Surgery and Translational Medicine, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Bianchi
authors.affiliation: Pathology, Department of Surgery and Translational Medicine, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Vania
authors.initials: V
authors.lastname: Vezzosi
authors.affiliation: Diagnostic Senology Unit, Radiology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Jacopo
authors.initials: J
authors.lastname: Nori
authors.affiliation: Statistics, Department of Statistics, Informatics and Application "G.Parenti", University of Florence, Viale Morgagni 59, 50134, Florence, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cecconi
authors.affiliation: Radiation-Oncology, Oncology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Icro
authors.initials: I
authors.lastname: Meattini
authors.affiliation: Radiation-Oncology, Oncology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Livi
authors.affiliation: Breast Unit Surgery, Oncology Department, Careggi University Hospital, L.go Brambilla 3, 50134, Florence, Italy. marco.bern@tin.it.
authors.forename: Marco
authors.identifier: http://orcid.org/0000-0002-9598-4860
authors.initials: M
authors.lastname: Bernini
mesh_terms: D001365:Axilla / Q000473:pathology; D001943:Breast Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology*; D008875:Middle Aged; D011446:Prospective Studies; D021701:Sentinel Lymph Node Biopsy / Q000379:methods
keywords: Breast cancer subtypes; Microinvasive breast cancer; Sentinel node biopsy