Ms Gribbin is moving to Palmerston North, where her partner works at Massey University.
"This community is amazingly generous. I'm very sad to be saying goodbye.
"I never shed a tear when I left Auckland after 25 years but I will be blubbering like a baby when I leave Wairarapa after three."
Mrs Buchanan, who lives in Masterton, will begin her new role as centre manager next month. She is returning to the Cancer Society after a three-year break, during which she was the cancer care co-ordinator at Wairarapa District Heath Board.
Mrs Buchanan also led the Fast Cancer Treatment Initiative in Wairarapa, which she said was "top of the country with getting patients into treatment quickly".
She has a background in management and health education and was initially the supportive care nurse at the Cancer Society. "I'm very excited to be coming back to the Cancer Society just to be able to continue to provide continuity of support for cancer patients in Wairarapa."
Mrs Buchanan said she was looking forward to working with her new team and the charity's volunteers.