Firefighters are exposed to carcinogens that may increase their risk of developing many types of occupational cancer. Many systematic reviews (SRs) have been produced with sometimes conflicting conclusions. In this overview of reviews, we aim to assess the conclusion consistency across the available systematic reviews on the cancer risk in firefighters. Literature searches were conducted in several indexed databases and grey literature to retrieve systematic reviews aiming to evaluate cancer incidence or cancer mortality in firefighters. Results from included SRs were analyzed according to the tumour site. Out of 1054 records identified by the search in the databases, a total of 11 SRs were ultimately included. The original studies (n = 104) analyzed in the SRs were published between 1959 and 2018. The results consistently reported a significant increase in the incidence of rectal, prostate, bladder and testicular cancers as well as mesothelioma and malignant melanoma in firefighters compared to the general population. The SRs also indicate that death rates from rectal cancer and non-Hodgkin's lymphoma are higher among firefighters. Consistent SR results suggest that several types of cancer may be more frequent in firefighters than in the general population.