European mistletoe has been used to treat a wide variety of physical and mental conditions. Mistletoe is best known as an additional treatment with other drugs for treating cancer.

Mistletoe extract may treat bladder cancer
After surgery for superficial bladder cancer, treatment with a mistletoe extract appears to be effective at reducing tumor recurrence. Mistletoe extracts have been shown to act favorably on proteins that affect cancer and have been widely used for many years as alternative therapy in patients with malignancies. In the current study, 30 patients with superficial bladder carcinoma received six weekly instillations of a standardized water-based mistletoe extract beginning about 4 weeks after surgery. The treatment was well tolerated at all concentrations and there were no reports of side effects.
At 12 months, nine tumors had recurred. In the 24 patients with so-called pTa G2 and pT1 G2 tumors, the recurrence rate was 33 percent, comparable to the recurrence rate in similar historical controls treated with BCG, the investigators point out.

Mistletoe Research Update
Adjuvant intravesical treatment of superficial bladder cancer with a standardized mistletoe extract.
J Urol. 2005 Jul;174(1):76-9.
Adjuvant intravesical immunotherapy with bacillus Calmette-Guerin (BCG) for noninvasive superficial bladder cancer has been shown to decrease tumor recurrence significantly. However, serious local and systemic side effects of this treatment have promoted the use of other immunoactive substances, which to date have failed to show efficacy equal to that of BCG immunotherapy. MATERIALS AND METHODS:: In the current phase I/II clinical trial an aqueous mistletoe extract standardized to mistletoe lectin was administered intravesically to 30 patients with superficial urothelial bladder carcinoma. About 4 weeks after transurethral resection each patient received 6 instillations at weekly intervals of 50 ml extract with mistletoe lectin concentrations between 10 and 5,000 ng/ml, which was retained in the bladder for 2 hours. Three patients per group received a dose, which was then doubled in the next group. Clinical followup consisted of examinations with cystoscopy, cytology and random biopsies. To detect cytokines and tumor necrosis factor-p75 receptor venous blood and urine samples were taken before instillation, and 2, 6 and 24 hours thereafter. CONCLUSIONS: From these results it is concluded that standardized mistletoe extract could be a potential alternative adjuvant therapy for superficial bladder cancer. Nevertheless, the optimal intravesical treatment regimen has yet to be defined.

Evaluation of the hypoglycemic effect and antioxidant activity of three Viscum album subspecies (European mistletoe) in streptozotocin-diabetic rats.
J Ethnopharmacol. 2005 Apr 8;98(1-2):95-102.
The acute hypoglycaemic effect of water and ethanolic extracts of three Viscum album subspecies, ssp. album, ssp. austriacum, ssp. abietis, were investigated in normoglycaemic and streptozotozocin-induced diabetic rats. The findings obtained in the experiments demonstrated that European mistletoe (Viscum album L.) subspecies possess potent antihyperglycaemic and antioxidant activity depending on host plant.

Vasodilator activity of the aqueous extract of Viscum album.
Fitoterapia. 2005 Mar;76(2):204-9.
The aqueous extract of mistletoe leaves showed a significant coronary vasodilator activity on the Langendorff's isolated and perfused heart model. The data obtained suggest that the aqueous extract of mistletoe contains some biologically active principles that may act as inducers of the nitric oxide/soluble guanylate cyclase pathway.