Background and aim: Extracts of Viscum album (European mistletoe) have immune-stimulatory and cytotoxic effects, with trials showing a well-established effect on the quality of life and prolonged survival in patients with advanced pancreatic cancer. Regression of tumours following intratumoural injection with Viscum album extract has been documented in individual cases. However, its influence on colon polyps has not been investigated.
Case presentation: We present the case of a 78-year-old Caucasian male who had undergone hemi-colectomy for a stage IIIC colon cancer but who refused adjuvant chemotherapy. Five years later a newly detected high-grade dysplasia colon adenoma was discovered; however, the adenoma could not be resected endoscopically and the patient did not consent to surgery. Intratumoural injections with Viscum album L extract (Quercus; Iscador®Qu) were administered twice in an attempt to limit tumour growth. Eight months after the second intratumoural injection the adenoma had disappeared and biopsy revealed no intraepithelial dysplasia or adenoma.
Conclusions: This is the first report showing complete regression of a colon adenoma after intratumoural injection with Viscum album extract. Prospective studies should evaluate if the treatment effect is reproducible and if this approach could be a useful pre-operative measure for colon adenomas too large for endoscopic resection.