Acetylsalicylic Acid and Head and Neck Cancer: Risk, Five-Year Survival, and Recurrence in over 11,000,000 Patients-A Retrospective Case-Control Study.

Background/Objectives: Acetylsalicylic acid (ASA) medication has been suggested to have a beneficial effect on cancer risk and survival. Therefore, this retrospective case-control study investigated the correlation between ASA and HNC in over 11,000,000 patients to investigate the impact of ASA intake on the risk of developing HNC, five-year survival rates, and the likelihood of secondary malignant neoplasms and malignant lymph node involvement. Methods: Retrospective clinical data was retrieved from a federated EHR network. Patients prescribed ASA were assigned to Cohort I, while those who were not prescribed ASA were assigned to Cohort II. Moreover, patients diagnosed with HNC, and prescribed ASA were assigned to Cohort III, while those with HNC but no history of ASA use were assigned to Cohort IV. Results: After matching, Cohorts I and II included 5,716,056 patients each. HNC incidence was significantly lower (OR 0.88; 95% CI 0.86-0.90) in Cohort I (+ASA) compared to Cohort II (-ASA). Furthermore, five-year survival was higher for patients taking ASA medication (survival probability 67.93%) compared to patients who did not (65.54%). These findings coincide with a lower risk of death of 22.8% (+ASA) compared to 23.6% (-ASA), which was statistically significant (p = 0.006). Patients with ASA intake also showed a lower risk of malignant neoplasms of lymph nodes (17.4% vs. 18.5%). Conclusions: Our analyses revealed a lower risk of HNC, a higher five-year survival rate, and a lower risk of malignant neoplasms of lymph nodes in patients with ASA medication. However, the retrospective design and the lack of evaluation of confounders limit the significance of our data, and, therefore, further analyses should be considered.