Thymic neuroendocrine tumor (TNET) is very rare and characterized by a tendency to invade adjacent structures, frequent metastasis, resistance to therapy, and a poor prognosis. Viscum album extracts (VAE) have shown immunological, apoptogenic, and cytotoxic properties.A 54-year-old Peruvian man was suffering from constant fatigue, cough, dyspnea, and fever for a couple of months.He was diagnosed with TNET (12.8 cm × 10 cm × 7 cm) stage IIIa, G1. Due to the size and extensive invasiveness (vena cava superior, also obstructing 85% of its lumen, pericardium, and pleura), the TNET was inoperable.We report the case of this patient who declined chemotherapy and was treated instead with sole subcutaneous VAE 3 times per week for 85 months. No other tumor-specific intervention was applied.Quality of life (QoL) improved substantially. The patient returned to work, and the tumor remained stable for 71 months. Thereafter, the tumor progressed, and the patient died 90 months after initial diagnosis. Besides self-limited local skin reactions around the application site, no side effects occurred.This is an exceptionally good course of disease of an inoperable, large, obstructing, and invasive TNET with a reduced baseline condition (Karnofsky index: 50-60) due to pronounced symptoms. Given the considerable reduction of symptoms and improved QoL following the onset of VAE therapy and other reports describing long disease stability and improvement of the QoL using VAE in different cancer types, we presume that the VAE treatment was supportive in this case. As TNETs are rare and few trials are available, future treatments of TNETs using VAE should be carefully documented and published to help determine whether further investigation of the use of VAE in TNET treatment is worthwhile.
