title: Expression and prognostic significance of lysozyme in male breast cancer.
abstract: BACKGROUND
  Lysozyme, one of the major protein components of human milk that is also synthesized by a significant percentage of breast carcinomas, is associated with lesions that have a favorable outcome in female breast cancer. Here we evaluate the expression and prognostic value of lysozyme in male breast cancer (MBC).
  
  
  METHODS
  Lysozyme expression was examined by immunohistochemical methods in a series of 60 MBC tissue sections and in 15 patients with gynecomastia. Staining was quantified using the HSCORE (histological score) system, which considers both the intensity and the percentage of cells staining at each intensity. Prognostic value of lysozyme was retrospectively evaluated by multivariate analysis taking into account conventional prognostic factors.
  
  
  RESULTS
  Lysozyme immunostaining was negative in all cases of gynecomastia. A total of 27 of 60 MBC sections (45%) stained positively for this protein, but there were clear differences among them with regard to the intensity and percentage of stained cells. Statistical analysis showed that lysozyme HSCORE values in relation to age, tumor size, nodal status, histological grade, estrogen receptor status, metastasis and histological type did not increase the statistical significance. Univariate analysis confirmed that both nodal involvement and lysozyme values were significant predictors of short-term relapse-free survival. Multivariate analysis, according to Cox's regression model, also showed that nodal status and lysozyme levels were significant independent indicators of short-term relapse-free survival.
  
  
  CONCLUSIONS
  Tumor expression of lysozyme is associated with lesions that have an unfavorable outcome in male breast cancer. This milk protein may be a new prognostic factor in patients with breast cancer.
authors.affiliation: Servicio de Cirugía General, Hospital Virgen de los Lirios de Alcoy, Alicante, Spain. serra_car@gva.es
authors.forename: Carlos
authors.initials: C
authors.lastname: Serra
authors.forename: Francisco
authors.initials: F
authors.lastname: Vizoso
authors.forename: Lorena
authors.initials: L
authors.lastname: Alonso
authors.forename: Juan C
authors.initials: JC
authors.lastname: Rodríguez
authors.forename: Luis O
authors.initials: LO
authors.lastname: González
authors.forename: María
authors.initials: M
authors.lastname: Fernández
authors.forename: María L
authors.initials: ML
authors.lastname: Lamelas
authors.forename: Luis M
authors.initials: LM
authors.lastname: Sánchez
authors.forename: José L
authors.initials: JL
authors.lastname: García-Muñiz
authors.forename: Aniceto
authors.initials: A
authors.lastname: Baltasar
authors.forename: Justo
authors.initials: J
authors.lastname: Medrano
mesh_terms: D000328:Adult; D000368:Aged; D018567:Breast Neoplasms, Male / Q000201:enzymology* / Q000401:mortality; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009113:Muramidase / Q000032:analysis*; D015996:Survival Rate
chemical_list: D009113:Muramidase