title: Natural History of Asymptomatic Papillary Thyroid Microcarcinoma: Time-Dependent Changes in Calcification and Vascularity During Active Surveillance.
abstract: BACKGROUND
  Prospective trials of non-surgical observation have shown progression rates of only 5-10% in patients with asymptomatic papillary microcarcinoma (PMC). This study investigated time-dependent changes in calcification patterns and tumor vascularity on ultrasonography (US) to clarify the natural course of PMC.
  
  
  METHODS
  We examined calcification patterns and tumor vascularity for 480 lesions in 384 patients. Calcification patterns were classified as: (A) none; (B) micro; (C) macro; or (D) rim. Tumor vascularity was classified as rich or poor via color Doppler US.
  
  
  RESULTS
  After a mean of 6.8 years of observation, 29 lesions (6.0%) had increased in size. Mean age for initial calcification pattern was 52.1 years for A (n = 135), 54.2 years for B (n = 235), 56.3 years for C (n = 96), and 60.1 years for D (n = 14), and the incidence rates of tumor enlargement were 9.6, 5.5, 3.2, and 0%, respectively. The cumulative rate of upgrade in calcification pattern was 51.8% at 10 years. Lesions with initially rich vascularity (n = 70) had significantly higher rate of tumor enlargement than those with poor vascularity (n = 410); however, the majority of tumor (61.4%) with initially rich vascularity had decreased their blood supply during the follow-up. Multivariate analysis showed that strong calcification (C or D) and poor vascularity at last examination correlated significantly with non-progressive disease.
  
  
  CONCLUSIONS
  PMCs in older patients showed significantly stronger calcification patterns and poorer vascularity. Both consolidation of calcification and loss of vascularity occurred in a time-dependent manner during observation and were significant indicators for non-progressive disease.
authors.affiliation: Division of Head and Neck, Cancer Institute Hospital of JFCR, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan. o-fukuoka@royal.ocn.ne.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Fukuoka
authors.affiliation: Division of Head and Neck, Cancer Institute Hospital of JFCR, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan. isugitani@nms.ac.jp.|Department of Endocrine Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan. isugitani@nms.ac.jp.
authors.forename: Iwao
authors.initials: I
authors.lastname: Sugitani
authors.affiliation: Division of Head and Neck, Cancer Institute Hospital of JFCR, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Ebina
authors.affiliation: Division of Head and Neck, Cancer Institute Hospital of JFCR, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Toda
authors.affiliation: Division of Head and Neck, Cancer Institute Hospital of JFCR, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kawabata
authors.affiliation: Department of Ultrasonography, Cancer Institute Hospital of JFCR, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology*; D002291:Carcinoma, Papillary / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D011446:Prospective Studies; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology*; D013997:Time Factors; D018615:Ultrasonography, Doppler, Color; D055815:Young Adult