The Ombudsman found that "surgery was too risky for symptom control only, unless [the patient] had wished to proceed on a fully informed basis."
Upholding the family's complaint he said he "found that the surgeon was acting at the limit of his skills in undertaking such complex surgery."
More top news
The Welsh Assembly election is less than a week away and the treatment and care of cancer is one of the more contested issues.
Tributes have been paid to an ambulance driver killed in a crash with another ambulance in North Wales.
Tonight is expected to be clear and dry - though some parts of Wales will experience frost.