[Does dark field microscopy according to Enderlein allow for cancer diagnosis? A prospective study].

Background: Dark field microscopy according to Enderlin claims to be able to detect forthcoming or beginning cancer at an early stage through minute abnormalities in the blood. In Germany and the USA, this method is used by an increasing number of physicians and health practitioners (non-medically qualified complementary practitioners), because this easy test seems to give important information about patients' health status.

Objective: Can dark field microscopy reliably detect cancer?

Materials and methods: In the course of a prospective study on iridology, blood samples were drawn for dark field microscopy in 110 patients. A health practitioner with several years of training in the field carried out the examination without prior information about the patients.

Results: Out of 12 patients with present tumor metastasis as confirmed by radiological methods (CT, MRI or ultra-sound) 3 were correctly identified. Analysis of sensitivity (0.25), specificity (0.64), positive (0.09) and negative (0.85) predictive values revealed unsatisfactory results.

Conclusion: Dark field micoroscopy does not seem to reliably detect the presence of cancer. Clinical use of the method can therefore not be recommended until future studies are conducted.