The odds of an early death rose with the number of GP consultations a patient attended, they found.
Those who had died had visited their GP an average of five times in the months before diagnosis, the study said.
Even surgeries that carried out lots of chest X-rays did not “appear to translate” to a reduction in early deaths from lung cancer, it said.
Lead scientist Dr Emma O’Dowd said the findings contrasted with her expectations that people with lung cancer were not visiting the doctor, accounting for Britain’s lower survival rates.
The study said out of the 20,142 people:
1,071 had been diagnosed at death
2,036 had died within 30 days of diagnosis
2,976 had died between 31 and 90 days after diagnosis
Dr O’Dowd said: “If patients are coming into the surgery and having a face-to-face interaction with a doctor, at least there is an opportunity to treat them.”
She said if people had not been visiting the doctor “at all”, it would have been more a public-engagement issue, which could be hard to manage.
“At least there is something we can do,” she said.
Other patterns in people dying an early death, defined as within three months of diagnosis, were highlighted by the study.
Men were more likely to die of lung cancer than women – 57%, or 11,468, of those who died were men. Of these, 3,585 died within 90 days of diagnosis compared with 2,498 of the women.
Dr O’Dowd said the fact more men than women smoked cigarettes in the past could be partly behind the gender gap.
And people in rural areas were more likely than those in urban areas to die an early death from lung cancer, said the paper.
Researchers called for software allowing doctors to type in symptoms of lung cancer to rapidly identify the fatal disease, which is the most difficult to diagnose as symptoms can look like other conditions, such as chest infections.
John Field, at the University of Liverpool, said the study was “one of the most in-depth primary care studies undertaken to date” on lung cancer.
He said: “The paper supports the argument that we do need to do a great deal more for potential lung cancer patients than what is provided at present.”
Data due from trials in the next two years would help decide the best, cost-effective treatments, he said.
Dr Penny Woods, the chief executive of the British Lung Foundation, said: “The finding that one in three UK lung cancer patients dies within three months of diagnosis is sadly a very telling consequence of late presentation and delayed diagnosis.
“These are major reasons why lung cancer continues to be the biggest cancer killer in the UK, and why survival rates in this country lag behind those throughout Europe and the US.
“Evidence suggests that well-funded awareness campaigns are proving very successful in increasing earlier diagnosis. A continuation and expansion of such campaigns will be crucial if we are to significantly improve lung cancer survival.”