Wikipedia explains that Josef Issels:
was a German physician known for promoting an alternative cancer therapy regimen, the Issels treatment. He claimed to cure cancer patients who had been declared incurable by conventional cancer treatments. During Issels' lifetime, his methods were controversial, and in 1961 he was charged with fraud and manslaughter for allegedly promising fraudulent cancer cures and for the subsequent deaths of patients under his care who refused standard cancer treatment. An initial conviction on the manslaughter charge was overturned in 1964 on the grounds that Issels had genuinely believed that his therapy could cure cancer. The Issels treatment is currently considered unproven and ineffective as a treatment for cancer.
I have searched and found different opinions:
Cancer Compass has mixed testimony.
Iain Carstair's Science And Religion Blog gives an anecdote of how the treatment worked for him and claims that some doctors planning an interview for a documentary discussed a strategy to dismiss the claims.
Is there scientific evidence that the technique used by Josef Issels - i.e. Issels Combination Therapy - is more effective than conventional treatments?