The invention provides the cold water extract of the sclerotium of the mushroom Lignosus rhinocerus or a high molecular weight fraction of the cold water extract, which is suitable for use in the treatment of cancer, particularly of breast and lung cancer. Accordingly, the present invention provides a Lignosus rhinocerus cold water extract for the preparation of a medicament for use in the treatment of cancer, characterized in that, the Lignosus rhinocerus cold water extract is obtainable by the extraction of the sclerotium of the mushroom Lignosus rhinocerus in water having a temperature in the range of from 0 to 10 ?C; wherein the Lignosus rhinocerus cold water extract provides a high molecular weight fraction of cold water extract for use in the treatment of breast cancer and/or lung cancer.