The SPSO investigated complaints raised by the patient’s family and ordered the health boards to apologise.
It said there was a failure to provide a reasonable standard of care and treatment to patient A, and that both authorities had failed to meet obligations on transparency around the patient’s care.
The watchdog also made a number of recommendations for improvements.
The SPSO took advice from a cancer surgeon on the services provided to patient A.
Commenting on NHS Grampian, the watchdog said: “We found that there was a failure to provide a reasonable standard of care and treatment to A, particularly in relation to delays in initiating treatment for their colorectal (bowel) cancer.”
It said reviews of the person’s care were inadequate, and that its handling of the complaint against it was “unreasonable”.
The SPSO said about NHS Orkney: “We found that there was a failure to provide a reasonable standard of care and treatment to A, particularly in relation to a failure to mark an MRI scan request as urgent, and a failure to report the results of scopes in the normal way.”