Are Risk Factors Common to Thyroid Cancer and Nodule? A Forty Years Observational Time-Trend Study

Angelo Carpi,Jeffrey Mechanick,Rossana Romani,Matteo Russo,Andrea Nicolini,Tommaso Simoncini,Giancarlo Di Coscio,Giuseppe Rossi,Anthony W I Lo

doi:10.1371/journal.pone.0047758

Abstract

A progressive increase in the incidence of thyroid cancer (TC) has been reported over the last few decades. This either reflects the increased number of newly discovered and accurately selected thyroid nodules with more sensitive technologies and a relative more potent carcinogenic effect of pathogenetic factors in malignant, but not benign nodules. This observational time-trend study addresses this issue by analysing the proportion of TC within 8411 consecutive thyroid nodule (TN) patients evaluated in Pisa by the same pathology Department and individual clinician over a four-decade period. From 1972 to 1979 surgery was used to detect TC among the TN patients: 1140 TN patients were operated on and 35 cancers were detected (3.1% of all the TN patients). Subsequently, needle aspiration techniques were used to select TN for surgery. From 1980 to 1992, 5403 TN patients were examined, 483 were selected for surgery, and 150 cancers were found (2.8% of all the TN patients). From 1993 to 2010, 1568 TN patients were examined, 143 were selected for surgery, and 46 cancers were found (2.9% of all the TN patients). Therefore, in the University Hospital of Pisa, and independent of preoperative TN selection protocols, these proportions of TN eventually found to harbor TC remained statistically unchanged over 40 years (p = 0.810). This finding suggests that pathogenic risk factors and more sensitive diagnostic technologies did not differentially affect the incidence of TN and TC.

Highlights

IntroductionThe hypotheses to explain these epidemiological data include the increasing use of procedures with progressively increasing sensitivity for diagnosing thyroid cancer (TC), as well as an increased exposure to environmental factors, such as ionizing radiation [1,2,3,4]
A progressive increase in the incidence of thyroid cancer (TC) has been reported in various countries over the last few decades [1,2,3].The hypotheses to explain these epidemiological data include the increasing use of procedures with progressively increasing sensitivity for diagnosing TC, as well as an increased exposure to environmental factors, such as ionizing radiation [1,2,3,4]
This study shows that the proportional rate of TC among patients with a thyroid nodule (TN) examined by the same physician within the University Hospital of Pisa and morphologically investigated at the same Institute of Pathology did not significantly change in the last 40 years

Summary

Introduction

The hypotheses to explain these epidemiological data include the increasing use of procedures with progressively increasing sensitivity for diagnosing TC, as well as an increased exposure to environmental factors, such as ionizing radiation [1,2,3,4] In the former case, compared with palpation alone on physical examination, the increased detection of TC within a thyroid nodule (TN) has been facilitated with the use of needle aspiration techniques (NAT; including fine-needle aspiration [FNA] for cytological examination; large-needle aspiration biopsy [LNAB] for histological examination and, if available, molecular analyses; and ultrasound [US]-guidance) [1,2,3,4,5,6,7]. The question arises whether the increased TC incidence is due to the improved NAT or rather, some increased or more potent effect of carcinogenic factors specific for malignant, but not benign TN [1,2,3]

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Results

Conclusion