Which of the following about tobacco and oral cancer are true? i. MC histological type – adenocarcinoma ii. Dose-response relationship iii. Synergistic interaction with alcohol iv. Associated with mutations in p53 gene. No association with smokeless tobacco
**Core Concept**
Tobacco use is a well-established risk factor for oral cancer, with a strong dose-response relationship. The association between tobacco and oral cancer involves complex interactions between tobacco carcinogens and host genetic factors.
**Why the Correct Answer is Right**
The majority of oral cancers are squamous cell carcinomas (SCCs), which arise from the mucosal lining of the oral cavity. Tobacco carcinogens, particularly polycyclic aromatic hydrocarbons (PAHs) and nitrosamines, bind to DNA and cause mutations, leading to SCC development. There is a clear dose-response relationship between tobacco consumption and the risk of oral cancer. Furthermore, tobacco and alcohol use can have a synergistic interaction, increasing the risk of oral cancer beyond the sum of their individual effects. Mutations in the p53 tumor suppressor gene are common in oral cancers, particularly in those associated with tobacco use.
**Why Each Wrong Option is Incorrect**
* **Option A:** i. MC histological type - adenocarcinoma: This is incorrect because the most common histological type of oral cancer is squamous cell carcinoma (SCC), not adenocarcinoma.
* **Option A:** ii. Dose-response relationship: This is incorrect because while there is a dose-response relationship between tobacco consumption and oral cancer risk, this option is paired with an incorrect statement about histological type.
* **Option A:** iii. Synergistic interaction with alcohol: This is incorrect because while tobacco and alcohol use can have a synergistic interaction, this option is paired with incorrect statements about histological type and dose-response relationship.
* **Option A:** iv. Associated with mutations in p53 gene: This is incorrect because while mutations in the p53 gene are common in oral cancers, this option is paired with incorrect statements about histological type, dose-response relationship, and synergistic interaction with alcohol.
* **Option A:** No association with smokeless tobacco: This is incorrect because smokeless tobacco use is also a risk factor for oral cancer, particularly SCC.
**Clinical Pearl / High-Yield Fact**
The association between tobacco use and oral cancer highlights the importance of tobacco cessation in preventing oral cancer development. The risk of oral cancer is significantly higher in individuals who use both tobacco and alcohol, emphasizing the need for dual cessation efforts.
**Correct Answer:** C.