The man, aged 58 at the time, visited Dr B four times from December 2013 to May the following year for help over gastric symptoms including pain, increased wind and difficulty swallowing. He had also lost weight.
At the first consultation, Dr B ordered blood tests, which came back normal, and prescribed anti-reflux drug omeprazole, plus an anti-nausea anti-vomiting drug.
On April 29, 2014, Dr B ordered repeat blood tests for "Mr A", including a tumour marker test called CEA (carcinoembryonic antigen).
"Mr A's CEA results were received on 30 April 2014, and the result was . . . outside the normal range. Dr B told HDC that her impression at the time was that this rise was 'not significant', and that therefore she did not take any further action at that time."
At his last visit to Dr B described by the commissioner, on May 8, 2014, the man was advised to take omeprazole and return for further review and referral for gastroscopy - a tube investigation down the throat - if he was not feeling better.
On September 19, 2014, the man saw his regular GP at the clinic, who referred him urgently for the oesophagoscopy - a viewing tube down the throat - and an x-ray.
The oesophagoscopy, done the next month, on October 6, revealed a "signet-ring" carcinoma in the lower oesophagus and he had chemotherapy and radiotherapy.
He told the commissioner's investigation that he is now very thin and cannot eat as much as he used to, or put on weight.
"Mr A consulted Dr B on four occasions over approximately six months [sic]. The evidence indicates that, from the first consultation and to varying degrees throughout that period, Mr A presented to Dr B with 'red flags' . . . , including unexplained weight loss and dysphagia [difficulty swallowing].
"Despite being responsible for arranging the necessary investigations based on the information presented during the extended period she was consulted, Dr B did not assess Mr A appropriately, and did not arrange for him to be referred for an endoscopy urgently."
The commissioner's recommendations included that Dr B make a written apology to the man and that she undertake training on use of CEA tumour marker tests.
The Medical Council is reviewing Dr B's competence.