The Vining family came to national prominence last year after Blair Vining, Ms Vining's husband, died from bowel cancer.
"Long waiting times (for treatment) are not only cruel and inhumane, but they kill people," Ms Vining said.
Mr Vining was diagnosed with terminal bowel cancer in October 2018.
He spent his final months campaigning for a national cancer agency, amassing more than 140,00 signatures on a petition to Parliament.
In a public forum before a board meeting in Dunedin today, Ms Vining said she still lacked faith in the SDHB's management of cancer patients, despite assurances that things would improve.
"Symptomatic patients should be seen."
Mr Vining was asked to wait eight weeks for an "urgent" appointment; a private consultation revealed his terminal diagnosis.
"The DHB appears to be rationing health care resources and denying them from people who need them."
SDHB chairman Dave Cull acknowledged Ms Vining's presentation, and asked her to join the board's endoscopy user group.