title: Growth potential of prolactinomas in men: is it really different from women?
abstract: BACKGROUND
  In comparison to prolactinomas in women, those in men are usually large tumors and have been suggested to have a higher proliferation activity. To elucidate the reason for the predominance of large tumors in men, we investigated the gender-related difference of prolactinomas including growth potential.
  
  
  METHODS
  We conducted a retrospective study comparing unselected 16 men and 27 women with prolactinoma concerning clinical and endocrine findings, tumor volume, and the mean Ki-67 (MIB-1) positive cell index (PCI).
  
  
  RESULTS
  Prolactinomas in men were larger in size (p = 0.0090), higher in serum prolactin level (p = 0.0359), and exhibited higher PCI (p = 0.0138) than those in women. However, the three factors-tumor volume, prolactin level, and the PCI-showed positive correlations with each other. There was no gender-related difference in the PCI when small tumors (<1.0 cm3) were excluded.
  
  
  CONCLUSIONS
  High PCI is associated with large tumors in both men and women. Because large tumors predominate in men, this is in fact consistent with the view that the biologic behavior of prolactinomas is different between the sexes.
authors.affiliation: Department of Neurosurgery, Tokyo Medical University, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishioka
authors.forename: Jo
authors.initials: J
authors.lastname: Haraoka
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Akada
mesh_terms: D000293:Adolescent; D000328:Adult; D018450:Disease Progression; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010911:Pituitary Neoplasms / Q000473:pathology*; D011388:Prolactin / Q000097:blood* / Q000494:pharmacology; D015175:Prolactinoma / Q000473:pathology*; D012189:Retrospective Studies; D012737:Sex Factors
chemical_list: D019394:Ki-67 Antigen; D011388:Prolactin