title: Negative prognostic influence of micropapillary pattern in stage IA lung adenocarcinoma.
abstract: OBJECTIVE
  There is uncertainty as to which factors determine the aggressiveness of lung adenocarcinoma with a micropapillary pattern (MPP). The present study aimed to clarify the influence of a MPP on the malignant aggressiveness of clinical stage IA lung adenocarcinoma.
  
  
  METHODS
  We retrospectively examined 347 consecutive patients with clinical stage IA lung adenocarcinoma who underwent complete resection. We defined MPP-positive as accounting for ≥5% of the entire tumour.
  
  
  RESULTS
  Forty-eight (14%) and 299 (86%) patients were MPP-positive and negative, respectively. Lymphatic (P = 0.003) and vessel (P = 0.029) invasion as well as lymph node metastasis (P = 0.002) were more frequent in the MPP-positive than negative group. Five-year disease-free survival (DFS) rates were significantly lower in the MPP-positive than negative group (69.7 vs 89.3%, P < 0.001). Multivariate analysis for DFS showed that MPP (P = 0.048), lymphatic invasion (P = 0.003) and vessel invasion (P = 0.002) were independent poor prognostic factors. In addition, higher proportions (<5%, 5-30% and ≥30%) of MPP were associated with a poorer prognosis (89.3, 76.0, and 48.1%, respectively; P < 0.001). The prognosis of patients with MPP-positive tumours and negative tumours harbouring lepidic and solid predominant growth patents did not differ (100 vs 96.8%, P = 0.564; 66.7 vs 62.5%, P = 0.791, respectively). On the other hand, the prognosis tended to be poorer for patients with papillary predominant MPP-positive tumours than for those with negative tumours (62.5 vs 82.5%, P = 0.075).
  
  
  CONCLUSIONS
  MPP has an effect on tumour malignancy and patients with tumours harbouring a higher ratio of MPP or papillary predominant subtypes have worse survival.
authors.affiliation: Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan.
authors.forename: Norifumi
authors.initials: N
authors.lastname: Tsubokawa
authors.affiliation: Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Mimae
authors.affiliation: Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Sasada
authors.affiliation: Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan.
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Yoshiya
authors.affiliation: Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mimura
authors.affiliation: Department of Respiratory Medicine, Kanagawa Cancer Center, Yokohama, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Murakami
authors.affiliation: Department of Thoracic Surgery, Kanagawa Cancer Center, Yokohama, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.affiliation: Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Miyata
authors.affiliation: Department of Thoracic Surgery, Kanagawa Cancer Center, Yokohama, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Nakayama
authors.affiliation: Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan morihito1217@hiroshima-u.ac.jp morihito1217@gmail.com.
authors.forename: Morihito
authors.initials: M
authors.lastname: Okada
mesh_terms: D000231:Adenocarcinoma, Papillary / Q000175:diagnosis* / Q000473:pathology / Q000556:secondary; D000368:Aged; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008207:Lymphatic Metastasis; D042601:Lymphatic Vessels / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D010994:Pleura / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies
keywords: Lung cancer; Micropapillary; Prognosis