Scrutiny Is Required

Letters to the Editor regarding the article Mistletoe Extract in Patients With Advanced Pancreatic Cancer by Kathrin Wode, Gunver S. Kienle, Ove Björ, Per Fransson, Lena Sharp, Nils O. Elander, Britt-Marie Bernhardson, Birgit Johansson, Christina Edwinsdotter Ardnor, Ursula Scheibling, Johanna Hök Nordberg, and Roger Henriksson in issue 11/2024

An additional large study of the effectiveness of treating patients with advanced pancreatic cancer with mistletoe extract has been published (MISTRAL [1]), which is intended to confirm the results of an earlier study (MAPAC [2, 3]). It needs to be scrutinized whether it is actually able to do so.

MISTRAL recruited only patients who received chemotherapy. The survival times were 7.8 to 8.3 months (mistletoe/control). Pancreas-specific best supportive care comprised all measures that are standard in Sweden.

MAPAC recruited exclusively untreated patients into the study. Survival times were 4.8 to 2.7 months (mistletoe/control). Pancreas-specific best supportive care was limited to analgesia in 150 of 220 cases and digestive enzymes in 22 of 220 cases.

The studies’ design is not comparable as regards survival times, since in MISTRAL, mistletoe therapy was administered as an adjunct to chemotherapy and was not tested against an untreated group.

As regards quality of life (QoL), both studies’ drastic differences in population and adjunct treatment hamper any comparison:

• The baseline data for QoL scores were vastly different: MISTRAL mistletoe 56.1, control 59.4; MAPAC mistletoe 32.0, control 34.8; an improvement in patients in the MISTRAL study was therefore barely possible (66.1 is the cut-off value for healthy individuals).
• Furthermore, 89% of patients in the MISTRAL study—but none whatsoever in MAPAC—received corticosteroids.

Because of its different setting as regards survival and because of the drastically different baseline and adjunct therapies as regards quality of life, MISTRAL is not comparable with MAPAC. Consequently, there are still two valid studies of mistletoe therapy in pancreatic cancer.

DOI: 10.3238/arztebl.m2024.0189

Dr. rer. nat. Wilfried Tröger

Freiburg, Germany

Prof. Dr. med. Daniel Galun

Belgrade, Serbia

Conflict of interest statement

Wilfried Tröger and Daniel Galun are authors of the MAPAC study.

References

1. Wode K, Kienle GS, Bjor O, et al.: Mistletoe extract in patients with advanced pancreatic cancer: a double-blind, randomized, placebo-controlled trial (MISTRAL). Dtsch Arztebl Int 2024; 121; 347–54.

2. Tröger W, Galun D, Reif M, Schumann A, Stankovic N, Milicevic M: Viscum album [L.] extract therapy in patients with locally advanced or metastatic pancreatic cancer: a randomised clinical trial on overall survival. Eur J Cancer 2013; 49: 3788–97.

3. Tröger W, Galun D, Reif M, Schumann A, Stankovic N, Milicevic M: Quality of life of patients with advanded pancreatic cancer during treatment with mistletoe. A randomized controlled trial. Dtsch Arztebl Int 2014; 111: 493–502.