The stigma attached to lung cancer can have far reaching consequences for patients, research suggests.
Lung cancer is associated with smoking
Oxford University researchers found many patients felt people blamed them for their illness because it is so strongly associated with smoking.
They also found that anti-smoking campaigns helped to fuel prejudice, which resulted in damaged relations with family, friends and doctors.
The study, of 45 patients, is published by the British Medical Journal.
Many patients, particularly those who had stopped smoking years ago or had never smoked, felt unjustly blamed for their illness.
One said: "People automatically think you've brought it on yourself and it's a sort of stigma."
Patients said that people had gone so far as to cross the road to avoid contact with them, and some said that family or friends had not been in touch since they heard about the diagnosis.
Some patients said they concealed their illness, and fear of stigmatisation deterred some from seeking all the help they needed.
There was also concern that treatment and research into lung cancer might be adversely affected by the stigma attached to the disease and those who smoke.
The researchers say it is important to make every effort to try to persuade people to quit smoking.
But they warn that strategies such as producing images of "dirty lungs" can upset people with smoking-related illness.
They suggest the best policy might be to target the workings of the tobacco industry, which may resonate with young people, while avoiding upset to people who are ill.
Writing in the BMJ, they say: "Efforts to help people to quit smoking are important, but clinical and educational interventions should be presented with care so as not to ad to the stigma experienced by patients with lung cancer and other smoking-related diseases."
Mike Unger, chief executive, Roy Castle Lung Cancer Foundation, agreed that there was a "huge" stigma attached to having lung cancer.
He told BBC News Online: "At a meeting I had with patients a few weeks ago without exception they were angry at the 'dirty lungs' image portrayed in recent adverts - this just reinforced the stereotype.
"This campaign might persuade some to stop smoking - briefly - but it does nothing to help those with lung cancer, a significant number of whom have never smoked."
He said people needed to be made aware that, although people developed lung cancer later on in life, it was the decision to start smoking as teenagers, leading to addiction, which put them at risk of the disease.
"Fundamentally, lung cancer is a 'paediatric' disease and the Foundation would much rather have such adverts focussing on lifestyle."
Professor Robert West, of Cancer Research UK's Health Behaviour Unit, said: "It is doubly tragic that individuals whose lives are blighted by lung cancer should also feel blamed for their illness.
"But anti-smoking campaigns nowadays recognise that smokers are not to blame: smokers want to stop but are trapped by nicotine addiction.
"The aim of the campaigns now is to encourage smokers to keep trying to quit and to use effective treatments to help them do so."