The young mum was told in April she had Hodgkin lymphoma, a rare blood cancer diagnosed in fewer than 650 Australians per year.

Now, her friends and colleagues are filling the void and showing their support, with a target of 160 life-saving donations in 12 weeks.

The campaign, led by Wirraway Street Early Learning and Kinder, has already accrued almost 40 donations and more donors are being urged to join.

Mrs Cashman said she started donating at age 18 because she "just loved the feeling of giving something that costs nothing but is worth so much to so many people".

Now having chemotherapy at Tamworth Cancer Centre - "definitely the hardest thing I've ever done" - she can't donate.

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Centre director Alison Smith said Mrs Cashman, who has a child at the centre, was "quite a giving kind of person", so the Wirraway family wanted to soften the blow.

"She said that was one of the saddest things [about the diagnosis]: that she would never be able to donate again," Mrs Smith said.

"So we thought: let's work out how many donations she would have done if she'd been able to continue - it worked out to be 160 - and said: 'That way, it doesn't matter that you can't donate anymore.'"

Centre staff and parents have pitched in during the past month - some have even given plasma twice during that time; as have people from local businesses Phil Hunt Parts and PRDNationwide.

The Donate for Trista campaign will run until the end of September.