title: The total number of tissue blocks per centimetre of tumor significantly correlated with the risk of distant metastasis in patients with minimally invasive follicular thyroid carcinoma.
abstract: BACKGROUND
  Given that careful histological examination plays a pivotal role in follicular thyroid carcinoma categorization, we hypothesize that the number of blocks taken at initial specimen review may be associated with survival outcomes of patients initially diagnosed with minimally invasive follicular thyroid carcinoma.
  
  
  METHODS
  A total of 162 patients with confirmed minimally invasive follicular thyroid carcinoma were analyzed. The number of tissue blocks taken from each patient was recorded and the number of blocks per each centimeter of tumor was calculated. A multivariate analysis was conducted to identify independent factors for distant metastasis-free survival.
  
  
  RESULTS
  After a mean follow-up of 197.88 ± 155.39 months, 7 (4.3%) patients developed distant metastasis during follow-up (group II). Relative to those who remained disease-free (group I), group II were significantly older at initial operation (p = 0.022), had larger tumors (p = 0.002) and fewer number of blocks taken/cm of tumor (p = 0.001). However, after adjusting for age at initial operation and tumor size, total number of tissue blocks taken/cm of tumor was the only independent determinant for distant metastasis-free survival (p = 0.049). The 10-year distant metastasis-free survival was significantly better in those who had ≥ 4 blocks/cm of tumor (n = 82) than those with ≤ 3 block/cm of tumor (n = 80) (100 vs. 84.7%, p = 0.005, by log rank).
  
  
  CONCLUSIONS
  Although our study was not able to identify the precise cause for the association between the total number of tissue blocks taken/cm of tumor and distant metastasis-free survival, our data support a more liberal approach in taking tissue blocks on thyroid nodules especially those showing well-differentiated follicular cell differentiation.
authors.affiliation: Department of Surgery, The University of Hong Kong, Hong Kong, SAR, China. blang@hku.hk.
authors.forename: Brian Hung-Hin
authors.initials: BH
authors.lastname: Lang
authors.affiliation: Department of Anatomical Pathology, The University of Hong Kong, Hong Kong, SAR, China.
authors.forename: Tony W H
authors.initials: TW
authors.lastname: Shek
authors.affiliation: Department of Surgery, The University of Hong Kong, Hong Kong, SAR, China.
authors.forename: Arnold L H
authors.initials: AL
authors.lastname: Wu
authors.affiliation: Department of Clinical Oncology, The University of Hong Kong, Hong Kong, SAR, China.
authors.forename: Koon Yat
authors.initials: KY
authors.lastname: Wan
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000401:mortality / Q000556:secondary*; D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D013961:Thyroid Gland / Q000473:pathology; D013964:Thyroid Neoplasms / Q000401:mortality / Q000473:pathology*
keywords: ATA risk stratification; Follicular neoplasm; capsular invasion; cervical lymph node metastasis; disease-free survival; fine needle aspiration cytology