Audrey Humpage died aged 70 a month after doctors at Walsall Manor Hospital said there was nothing more they could do.
However, a postmortem later found the Mrs Humpage, of Warewell Road, did not have the cancer. She had a pelvic abscess.
Treatment could have been given for the pelvic condition, which was a contributory factor toward her death.
Mrs Humpage's three children Chris, 42, Martin,44 and Angela, 47 attended a Walsall Healthcare NHS Trust board meeting yesterday to discuss the case.
During the meeting, which hospital bosses used to inform the family of changes made in the wake of Mrs Humpage's death, her son Chris said: "We all know that we are never going to get out mother back but we intend to continue fighting so those who believe are to blame for her death are held properly accountable.
"I want to be able to go to her grave and tell her that I am fighting for the justice she deserves."
Richard Kirby, Manor Hospital chief executive, said: "The intention of this discussion is to make sure we understand what went wrong with the care of Mrs Humpage.
"On behalf of this board I want to say sorry for what happened.
"I can't imagine the distress this has caused and I hope we can learn from this.
"There were a number of significant failings in the care we provided that we recognise."
In response to an Ombudsman report into the failings surrounding Mrs Humpage's death, the hospital have brought in changes including the implementation of a new end of life care treatment to replace the Liverpool Care Pathway.
Mrs Humpage died at Compton Hospice on January 9 last year.
The Health Service Ombudsman has reviewed the case and found that Walsall Healthcare NHS Trust was guilty of numerous failings.