Background There has been an increasing interest in systematic reviews of traditional Chinese medicine (SR-TCM) over the past 10 years. Little is known about the quality of evidence of SR-TCM.

Methods GRADE (Grading of Recommendations Assessment, Development and Evaluation) system is a tool to rate evidence quality of SRs and other evidence body. We searched CBM (China Biomedicine Database) from 1978 to 2012 and included all SR-TCM in the field of cancer treatment. We used GRADE system to assess the quality of evidence of those SRs. Two reviewers independently screened the titles and abstracts of identified studies. Full texts of potentially included articles were further assessed. Disagreements were resolved by discussion.

Results The preliminary results showed that the quality of evidence of SR-TCM were: high (1%), moderate (25%), low (50%), very low (24%). We also compared with the quality of evidence of SRs published in Chinese medical journals (5%, 27%, 49%, 19%) and Cochrane SRs (5%, 27%, 49%, 19%). Risk of bias, inconsistency and publication bias were the major factors for downgrading evidence of SR-TCM.

Conclusion More and more SR-TCM had been published in Chinese medical journals, however, the proportion of high quality evidence is lower and the very low quality evidence is higher compared with national and international levels.