Year: 2026 | Month: September | Volume: 13 | Issue: 9 | Pages: 215-238
DOI: https://doi.org/10.52403/ijrr.20260923
39-Fold Increased Oral Cancer Risk with Shammah Use in Yemen: A Systematic Review and Meta-Analysis
Mahmood Md. Mohsen Al-Sakkaf1, Sami A. Hosain Al-Sakkaf2, Akram M. Mohammed Al-Sakkaf1
1Faculty of Medicine and Health Sciences, University of Aden, Aden, Yemen
2Faculty of Dentistry, University of Hodeidah, Hodeidah, Yemen
Corresponding Author: Akram M. Mohammed Al-Sakkaf
ABSTRACT
Objective: To systematically review the association between shammah use and oral cancer risk in Yemeni populations.
Methods: Systematic review and meta-analysis of 60 studies across multiple databases to December 2025. Random-effects meta-analysis, GRADE certainty assessment.
Results: Meta-analysis of three case-control studies (178 cases, 356 controls) yielded a pooled odds ratio of 38.74 (95% CI: 19.50-76.96; I²=0%; GRADE: LOW certainty). Only one of three studies was conducted in Yemen (OR 39.00; 95% CI: 14.00-105.00; GRADE: VERY LOW certainty), with the others from neighboring Saudi Arabia where shammah use is also prevalent. The generalizability of the pooled estimate to Yemeni populations is uncertain due to the limited number of Yemeni studies. Shammah-associated lesions showed epithelial dysplasia in 43% of biopsied lesions in a single study (may reflect selection bias). User awareness of cancer risk is critically low among surveyed populations (2.98% of university students specifically identified cancer as a risk; 19% of shammah users knew it could cause cancer). There are severe knowledge gaps among surveyed dental professionals (84% unable to identify risk factors).
Conclusion: Low- to very low-certainty evidence suggests shammah use is associated with a substantially elevated risk of oral cancer (pooled OR 38.74). However, this estimate is based on only three case-control studies, two from Saudi Arabia, and therefore may not precisely reflect the risk in Yemeni populations. The single Yemeni study reported a similar estimate (OR 39.00), but this requires confirmation in larger Yemeni studies. Single-study evidence indicates that shammah-associated lesions may have high malignant potential, but this requires confirmation with systematic biopsy protocols. Product bacteriome findings are hypothesis-generating and of unknown relevance to human carcinogenesis. Critically low user awareness and severe dental workforce training gaps constitute major implementation barriers. Without urgent intervention including cessation campaigns, health warnings, curriculum reform, and a national cancer registry, oral cancer will continue to claim preventable lives in Yemen.
Keywords: Carcinogen; epidemiology; smokeless tobacco; oral potentially malignant lesions; Yemen
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