Progression of precancerous lesions to oral cancer: Results based on the Taiwan National Health Insurance Database Ie-Bin Lian a , Yao-Ting Tseng a , Che-Chun Su a,b,⇑ , Kuo-Yang Tsai c,d,⇑ a Graduate Institute of Statistics and Information Science, National Changhua University of Education, Changhua 500, Taiwan b Department of Internal Medicine, Changhua Christian Hospital, 135, Nan-Hsiao Street, Changhua 500, Taiwan c Department of Oral and Maxillofacial Surgery, Changhua Christian Hospital, 135, Nan-Hsiao Street, Changhua 500, Taiwan d Center for General Education, Providence University, Taichung 433, Taiwan article info Article history: Received 22 October 2012 Received in revised form 21 November 2012 Accepted 11 December 2012 Available online 27 December 2012 Keywords: Premalignant lesions Oral submucous fibrosis Oral leukoplakia Epidemiology summary Background: Oral cancer (OC) is the leading cause of death from cancer in men between the ages of 25 and 44 in Taiwan. The survival rate for the last stage of OC is <20% while that for the earliest stage is >75%, which suggests the importance of the diagnosis of oral precancerous lesions (OPLs) in reducing OC mortality. The aim of this study was to analyze the time to OC event after OPL diagnosis, and to sug- gest the surveillance period necessary according to OPL type. Materials and methods: This was a retrospective cohort study based on 1.0 million people randomly selected from the Taiwan National Health Insurance Database, which provided data on 3058 adult male patients aged P20 years who were diagnosed with OPL for the first time between 1996 and 2009. The patient population was divided into two groups according to the type of lesion: oral submucous fibrosis (OSF) or oral leukoplakia (OLE). Age-standardized incidence rate (ASIR) and hazards rate (HR) were then estimated. Results: The ASIR for OPL showed an increasing trend over the study period, the main contributor to this being OSF. The OSF group demonstrated a higher OC incidence rate than the OLE group. Conclusion: Patients with both OLE and OSF carry a higher risk for OC than those with either OLE or OSF alone, and they may also experience malignant transformation at an earlier date (mostly within 5 years). The 5- and 10-year OC rate for both OLE and OSF was found to be 5% and around 10%, respectively. How- ever, 10 years after the diagnosis of OPL, OSF carries a higher risk of developing into OC than OLE. Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved. Introduction Oral cancer (OC) is one of the malignancies with the most rap- idly increasing incidence in Taiwan, 1 and the leading cause of death from cancer in men between the ages of 25 and 44. 2 Because most patients with this malignancy are aged 30–59, considerable losses are incurred by society. A recent investigation in the USA 3 indicates that the overall 5-year survival rate for OC patients is 60%. This low survival rate is due to the high incidence of metastasis, for which the 5-year sur- vival rate is <28%. It is obvious that early diagnosis of OC or, partic- ularly, oral precancerous lesions (OPLs) could greatly improve survival rates. Monitoring progression from OPL to possible malig- nancy is important in the prevention of OC. The most common types of OPL are oral leukoplakia (OLE), oral submucous fibrosis (OSF), oral lichen planus, and verrucous hyperplasia with or without dysplasia. Records of cases involving oral lichen planus are rare in the Taiwan Health Insurance Data- base (THID), and it is also difficult to distinguish the diagnosis of verrucous hyperplasia from that of other oral diseases like oral ulceration. Therefore, only two types of OPL, OLE and OSF, were considered in this paper. Betel quid chewing has long been blamed as the major cause of oral cancer in Taiwan, 4 with cigarette smoking and alcohol drink- ing being the next most important risk factors. Besides these three factors, several studies have also indicated that certain environ- mental heavy metals, including arsenic, chromium and nickel may play roles in the progression and prognosis of OC. 5–7 The risk factors for OPL in Taiwan coincide basically with those for OC. A case-control study by Shiu et al. 8 found that betel quid chewing, cigarette smoking, and alcohol drinking are risk factors for OLE; in particular, the group practicing betel quid chewing had a higher odds ratio (OR = 26) than the ‘‘never practiced betel quid chewing’’ group. Yen et al. 9 further confirmed the risks from betel quid chewing by demonstrating a significant dose–response effect. Individuals consuming greater quantities of cigarettes and betel quid had a higher accumulated hazard for OPL, and the 1368-8375/$ - see front matter Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.oraloncology.2012.12.004 ⇑ Corresponding authors. Address: Department of Oral and Maxillofacial Surgery, Changhua Christian Hospital, 135, Nan-Hsiao Street, Changhua 500, Taiwan (C.-C. Su). E-mail addresses: 115025@cch.org.tw (C.-C. Su), 72837@cch.org.tw (K.-Y. Tsai). Oral Oncology 49 (2013) 427–430 Contents lists available at SciVerse ScienceDirect Oral Oncology journal homepage: www.elsevier.com/locate/oraloncology