"In my opinion, a number of oversight's in the GP's care contributed to a delay in the woman's diagnosis of bowel cancer, this delaying her treatment," she said.
"I do acknowledge the complexity and chronicity of the woman's medical conditions was a difficult background on which to provide care and diagnosis, and I have taken this into account."
She said the GP had missed multiple opportunities in 2016 and 2017 to follow up on stool and blood tests and make a referral for an endoscopy.
The GP should also have recognised unexplained iron deficiencies and examine the woman's abdomen, and ordered repeat blood tests to rule out progressive iron deficiency.
The woman presented to the medical centre in January 2018 with tailbone pain and a different GP found a rectal mass.
She underwent chemotherapy, surgery and palliative chemotherapy and radiotherapy, but passed away in 2019.
Caldwell found the GP had breached the Code of Health and Disability Services Consumers' Rights. However she found the GP's errors were "individual" and the medical centre had not breached the code.
The report highlights that follow-up tests and appointments were essential for "timely diagnosis".
Caldwell recommended the GP review cognitive factors in diagnosis from the Royal Australian College of Physicians, and report back to the HDC on his reflections.
The GP was also asked to write a written apology to the woman's family.