Survival Outcomes in Adenoid Cystic Carcinoma of the Head and Neck: A Systematic Review of 17 497 Cases and Meta‐Analysis

ABSTRACT Background Adenoid cystic carcinoma (ACC) is a slow‐growing tumor with variable outcomes, making follow‐up protocols challenging. This review analyzed outcomes in ACC, focusing on patterns and factors related to adverse prognoses. Methods A search was conducted on March 25, 2024, in MEDLINE, PubMed, Scopus, and EMBASE. Studies analyzing ACC survival were included, while those lacking these data or focusing on a single ACC site were excluded. The Joanna Briggs Institute's Critical Appraisal tool was used to assess the risk of bias, and the metanalysis was performed using R software. Results Among 57 studies (17 497 patients), ACC predominantly affected women (mean age: 52.69 years) and occurred mainly in minor salivary glands. Distant metastasis was the most frequent adverse outcome, occurring at 34.8 months on average. Locoregional metastasis and local recurrence occurred at 27.5 and 31.3 months, respectively. Five‐, 10‐, 15‐, and 20‐year survival rates were 73.8%, 48.5%, 42.3%, and 26.5%, respectively. Poor survival predictors included advanced T stage, positive lymph nodes, solid tumors, distant metastasis, and positive surgical margins. Conclusions Distant metastasis is the most frequent adverse outcome in ACC, and prognostic factors are related to advanced and residual tumors.