Mr Hamilton, of Ashtonfield, went under the knife and had a melanoma 3.1 mm deep cut from his back and his upper left-side lymph nodes were removed.

As a follow-up, the melanoma unit put Mr Hamilton on a three-year course of "vaccinia melanoma cell lysates", or VMCL, which aims to prevent the return of the melanoma by bolstering the immune system.

For Mr Hamilton, the treatment became something to hang on to, and he was horrified to be told in March this year that his treatment had to stop.

At the time, he says he was told "virtually nothing, only that they had to stop it while they got some processes in place".

Mater general manager Colin Osborne confirmed this week that Mr Hamilton was one of 42 patients whose VMCL treatment was stopped for up to three months because the hospital believed its patient consent forms were out of date.

It's an explanation that angers Mr Hamilton and melanoma unit director of research Professor Peter Hersey, who called it a "huge over-reaction".

In a September letter to Mr Hamilton, Mr Osborne said: "Although the interruption to this course of treatment is regrettable, hospital management made this decision in order to improve our processes concerning documentation and administration of VMCL.

"With the benefit of hindsight this delay could have been reduced and I apologise that this has occurred. I wish to reassure you that any changes we make to our services are made in the best interest of our patients."

Mr Osborne said this week that VMCL was an experimental treatment that had been developed to trial stage but had not gone on to become a licensed drug.

It seemed to work for some patients but not others.

He said stopping the drug for up to three months was unlikely to have done harm.

"While the trials indicate that there may be benefits of the vaccine for a very small proportion of patients who receive it, it is not statistically significant from a scientific perspective and therefore not possible to determine that there were any detrimental clinical implications of the missed injections."