Objective: To investigate the application of the grey screening method in the research of the prescriptions treating colorectal cancer (CRC). Method: According to the inclusion criteria

132 cases of prescriptions were collected

involving 260 herbal medicines

with the cumulative frequency of 2 363 times. Through the self-built ‘syndrome-herbal properties-frequency database’

the grey screening method was adopted to analyze the rules of traditional Chinese medicine (TCM) prescriptions for CRC. Result: In prescribers for TCM in treatment of CRC

doctors gave priority to strengthening and consolidating body resistance

and also consideration to clearing heat-toxicity

promoting blood circulation for removing blood stasis

and regulating Qi-flowing for hemostasis. Moreover

strengthening vital Qi and eliminating pathogenic factor should be taken into account

which reflects TCM's holism of and treatment based on syndrome differentiation. The analysis on core drugs shall be made to determine that the treatment of CRC medicines often had effects in tonifying deficiency

clearing heat

promoting blood circulation for removing blood stasis. The top 5 herbs with the hugest grey correlation degree are Saposhnikoviae Radix

Scutellariae Radix

Sanguisorbae Radix

Rhei Radix et Rhizoma

Rehmanniae Radix

and evolved into 5 basic prescriptions. Conclusion: The grey theory

in the combination of the grey screening method for multivariate analysis

conforms to the thought of ‘treatment based on syndrome differentiation’ in TCM

and provides new ideas for clinical medications.