Table 4. Estimates of medical, non-medical, and indirect costs of oral cancer presented in the methods of studies from 2001 to 2020.

Study	Direct costs							Indirect cost
	Medical costs						Non-medical costs	Absenteeism	Early Death
	Surgery	Chemotherapy	Radiotherapy	Follow up	Medications	Exams
Longitudinal studies
1. Kim, 2011 [23]	✓	✓	✓	✓	✓	✓
2. Polesel, 2019 [26]	✓	✓	✓	✓	✓	✓
3. Jacobson, 2012 [24]	✓	✓	✓	✓	✓
4. Pollaers, 2019 [25]	✓	✓	✓	✓	✓	✓
5. Huang, 2020 [27]	✓	✓	✓	✓	✓	✓
Cross-sectional and case control studies
6. Rezapour, 2018 [29]	✓	✓	✓	✓		✓	✓	✓	✓
7. van Aghtoven, 2001 [35]	✓	✓	✓	✓	✓	✓
8. Fisher, 2018 [36]		✓		✓	✓
9. Nijdam, 2005 [32]	✓	✓	✓	✓	✓	✓
10. Amarasinghe, 2019 [18]	✓	✓	✓	✓	✓	✓	✓	✓
11. Goyal, 2014 [33]	✓	✓	✓	✓
12. Zavras, 2002 [37]	✓	✓	✓	✓	✓	✓
13. van der Linden, 2016 [38]	✓	✓	✓		✓	✓
14. Epstein, 2008 [34]	✓	✓	✓	✓	✓
15. Lafuma, 2019 [30]		✓		✓	✓	✓	✓	✓
16. Patterson, 2020 [31]										✓
17. Han, 2010 [39]	✓	✓	✓	✓	✓	✓	✓
18. Enomoto, 2015 [40]				✓
19. Lairson, 2017 [41]	✓	✓	✓	✓	✓	✓
20. Kim, 2020 [19]	✓	✓	✓	✓	✓	✓	✓	✓		✓
Cross-sectional studies based on information system data
21. Vatanasapt, 2012 [20]	✓			✓		✓
22. Klussmann, 2013 [28]	✓	✓	✓		✓	✓		✓
23. Keeping, 2018 [21]	✓	✓	✓	✓	✓	✓
24. Milani, 2021 [22]	✓	✓	✓	✓	✓	✓	✓