title: PIK3CA mutation and histological type in breast carcinoma: high frequency of mutations in lobular carcinoma.
abstract: Mutations in the PIK3CA gene have recently been reported in different human neoplasms, including breast cancer. This paper reports the results of a systematic analysis of PIK3CA mutations in different histological types of breast carcinoma. One hundred and eighty invasive breast carcinomas, comprising 74 ductal, 56 lobular, 22 mucinous, 20 medullary, and eight papillary, were selected on the basis of their histological type in a consecutive series of 780 breast cancers. Exons 1-20 of the PIK3CA gene were subjected to SSCP analysis followed by direct sequencing. PIK3CA mutations were observed in 46 (26%) of the 180 tumours examined: 23 (50%) mutations were located in exon 9, and 23 (50%) in exon 20. Mutations were frequent in lobular (46%), less frequent in ductal (22%), and uncommon in medullary (10%), mucinous (5%), and papillary tumours (12%) (p = 0.0002). Mutations in exon 9 were more frequent in lobular carcinomas (30% of cases) than in the other histological types (less than 5% of cases) (p = 0.00014). No significant differences were observed in the distribution of mutations in exon 20. There was no significant correlation between PIK3CA mutations and other clinicopathological and biological variables, including age, tumour size, lymph node metastases, oestrogen receptor (ER) status, progesterone receptor (PgR) status, p53 gene mutations, and p53 protein expression. The findings indicate that in invasive breast carcinomas, PIK3CA alterations are mainly present in lobular and ductal tumours, whereas the other histological types, known to be associated with a favourable prognosis, show a very low incidence of PIK3CA mutations.
authors.affiliation: Clinical Research Center, Center of Excellence on Aging, University-Foundation, Chieti, Italy.
authors.forename: Fiamma
authors.initials: F
authors.lastname: Buttitta
authors.forename: Lara
authors.initials: L
authors.lastname: Felicioni
authors.forename: Fabio
authors.initials: F
authors.lastname: Barassi
authors.forename: Carla
authors.initials: C
authors.lastname: Martella
authors.forename: Diego
authors.initials: D
authors.lastname: Paolizzi
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Fresu
authors.forename: Simona
authors.initials: S
authors.lastname: Salvatore
authors.forename: Franco
authors.initials: F
authors.lastname: Cuccurullo
authors.forename: Andrea
authors.initials: A
authors.lastname: Mezzetti
authors.forename: Daniela
authors.initials: D
authors.lastname: Campani
authors.forename: Antonio
authors.initials: A
authors.lastname: Marchetti
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism / Q000473:pathology; D018275:Carcinoma, Lobular / Q000378:metabolism* / Q000473:pathology*; D016009:Chi-Square Distribution; D058534:Class I Phosphatidylinositol 3-Kinases; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D019394:Ki-67 Antigen / Q000032:analysis; D016015:Logistic Models; D008875:Middle Aged; D020125:Mutation, Missense; D019869:Phosphatidylinositol 3-Kinases / Q000032:analysis / Q000235:genetics*; D018807:Polymorphism, Single-Stranded Conformational; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis
chemical_list: D058534:Class I Phosphatidylinositol 3-Kinases; D019394:Ki-67 Antigen; D019869:Phosphatidylinositol 3-Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; C484760:PIK3CA protein, human