Helen Kelly, former president of the New Zealand Council of Trade Unions, is optimistic a revolutionary Cuban lung cancer treatment can help her.

Helen Kelly is in a hospice but hope is far from over for the former union boss.

After travelling to Cuba to take a revolutionary treatment for the lung cancer that was predicted to kill her more than a year ago, the former Council of Trade Unions president returned to New Zealand on Monday.

She is now in Wellington's Mary Potter Hospice, where she said it was "too early to tell" if the Cuban treatment had worked.

The hospice stay was for pain management in the spine and she expected to be out again "if I can sort this out".

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In Cuba she was given CIMAvax, a Cuban-developed drug described in a post on the American Association for Cancer Research's page as "targeting and effectively depleting" the growth of lung cancer.

"The cancer starves and its progress slows, prolonging patients' lives."

Even in the hospice she continued to campaign as much as she could.

She has been leading the charge to legalise medicinal cannabis and has been openly taking the drug to help with the pain, not least from where a tumour was that broke her spine.

She had to stop taking cannabis to travel to Cuba but had now started again.

The trip home was arduous and took a lot out of her but she had no regrets.

"I'm glad I did it – I have the drugs here to finish off."

She was diagnosed with terminal lung cancer in February last year and was initially given about seven weeks to live.

America's CBC News said CIMAvax was a product of Cuba's "surging" biotech industry.

The Cuban regime invested heavily in healthcare and medical research and the country now cheaply produced roughly 70 per cent of its pharmaceuticals.

Medical tourists have travelled from around the world to get CIMAvax, which is unavailable outside Cuba and some Latin American countries.