Disruptions of normal apoptotic pathways, which are mainly mediated by caspases, play an essential role in cancer development. Caspase-8 (CASP8) is encoded by the CASP8 gene and is centrally involved in the apoptosis of T lymphocytes. The association between a six-nucleotide deletion polymorphism (-652 6N del) of the CASP8 gene and the risk of cancer is widely reported; however, study results have been inconsistent and contradictory. To evaluate the association between the CASP8 -652 6N del polymorphism and the risk of cancer and to overcome the limitations of any individual study, a meta-analysis based on a total of 23 700 cases and 26 412 controls from 30 case-control studies was conducted. The results of the overall analysis suggested that the CASP8 -652 6N del polymorphism is associated with decreased risk of cancer for the allele contrast [del versus ins: odd ratio (OR) = 0.86, 95% confidence interval (CI) = 0.80-0.92], the additive genetic model (del/del versus ins/ins: OR = 0.78, 95% CI = 0.69-0.88), the dominant genetic model (del/del+del/ins versus ins/ins: OR = 0.83, 95% CI = 0.78-0.89) and the recessive genetic model (del/del versus ins/ins+del/ins: OR = 0.84, 95% CI = 0.75-0.93). In addition, after stratification for ethnicity and cancer type, significantly reduced risk was found for Asians and Caucasians as well as for individuals in the colorectal cancer group and the 'other cancers' group. Accordingly, there is an association between the CASP8 -652 6N del polymorphism and reduced cancer risk, especially among Asians, Caucasians and those with colorectal cancer. However, further research, such as studies focusing on additional ethnic groups and cancer types, is needed to provide a more exact and comprehensive synthesis conclusion.