Lung cancer causes almost a quarter of all cancer deaths in Scotland ... so why does it receive just 3.1% of research money ?

In contrast, around £5.4 million was spent on colon and rectal cancer, around £3.5m on prostate cancer and just over £3m on breast cancer research. Yet lung cancer kills more people in Scotland than all these other cancers combined.

Campaigners say the stigma resulting from the strong association between smoking and lung cancer means it is often an "invisible disease".

Lorraine Dallas, director of information and support at the Roy Castle Lung Cancer Foundation, said: "The relationship between lung cancer and smoking has played into the perception that it is something that is perhaps not as worthy as other situations. It has been something that has been seen as less attractive and therefore money has not gone into it."

She added: "Treatment and cure rates haven't been as high as people are presenting late (for diagnosis) because there is a huge amount of stigma and guilt and because it is a very difficult to detect cancer.

"Therefore, you get this perpetuation of a myth that lung cancer is not treatable and not curable - which it is, if we can get it early."

The link between smoking and lung cancer was established in the 1950s. Perhaps less well-known is that around 10-15% of those who develop the disease have never smoked.

One recent high-profile case was novelist Sian Busby, the wife of BBC business editor Robert Peston - a lifelong non-smoker who died from lung cancer last year at the age of 51.

Dallas said: "It can be a really difficult issue for non-smokers in terms of the public perception of lung cancer as focused around smoking.

"They have got a diagnosis and the first thing people will say is, 'I didn't know you smoked': it compounds that sense that it is your own fault.

"It illustrates the fact there is something going on in the background in terms of social judgment and hierarchy, in which it [lung cancer] is seen as less worthy as there are behavioural factors which influence your likelihood of developing it. That is something that has to be addressed."

Advances in screening and treatment mean patients in Scotland are now more likely to survive many cancers.

For example, over 86% of women in Scotland survive at least five years after a diagnosis of breast cancer, compared with around 65% in the 1980s. But when it comes to lung cancer, there has been little progress over the past 30 years. Only around 8% of patients survive at least five years after diagnosis, compared with around 6% in the 1980s.

Dallas previously worked for a breast cancer charity before taking up her role at the Roy Castle Lung Cancer Foundation, which aims to raise £2m for research each year over the next five years.

She said breast cancer had a high profile as there were many survivors willing to tell their stories. But the appalling death rate means lung cancer often lacks the voices of those who have survived the disease.

"In some cases there is also lack of interest because of the assumption that because of smoking it is not a story you want to hear," she said. "That perpetuates that problem. The people become less visible as no-one wants to hear their stories."

The data on cancer research spend was compiled by the National Cancer Research Institute (NCRI), a partnership which co-ordinates cancer research funding of 22 major organisations involved in the field.

The figures show around £61.5m was spent on cancer research in Scotland in 2012, with just under £40m spend on "generic" research into the disease. The amount of research funding for specific cancers was around £21.7m. Only pancreatic cancer - which claims around 700 lives a year - received a smaller proportion of this total than lung cancer, at just under £500,000, or 2.3% of overall funding.

Dr James Cant, head of Scotland and Northern Ireland at the British Lung Foundation, said: "You have got a situation where, with a condition like breast cancer, which is perceived to be blameless and affects mainly relatively young women, money is literally thrown at it.

"Conversely lung cancer and other lung conditions are often associated with Scotland's old heavy industries and an awful lot of the social habits that went along with them. It is a slightly complicated matter because of the smoking issue.

"If we could nail that on the head - and I am pretty confident that in the next generation we will start to - that will reduce a huge amount of lung disease, particularly lung cancer.

"But on the other hand, it is very important to remember that anything between 15-20% of people who have lung cancer have no smoking history at all."

Cant said another problem was that lung cancer has traditionally been viewed as a "death sentence", with the incorrect assumption that little can be done to treat it.

People are then reluctant to seek help for symptoms early, when treatment is more effective, resulting in a "catch-22" situation.

The fact the majority of lung cancer patients are diagnosed at a late stage - more than two-thirds - also hinders research into the disease, according to Jamie Meredith, head of programme funding at Cancer Research UK.

"Unfortunately, it is very difficult to put someone on a clinical trial if they are very, very poorly," he said.

"It is difficult to take biopsies and to undertake surgery if someone is very, very poorly, so that actually makes it quite difficult to study the biology of the disease as well.

"With breast cancer, where the disease is detected much earlier, surgery, clinical trials and so on are much easier to undertake. It's easier to ask certain research questions in that context than it is with lung cancer."

Meredith said the difficulty of carrying out studies meant there was a relatively small number of researchers working in the field of lung cancer at the moment, so there were fewer applications for funding than for other types of cancer.

He added: "It is not that we don't want to fund science in a particular area, it is just we simply don't see the applications coming in. If they are not there, we can't fund them.

"It is something we are trying to address over the next few years. We certainly don't look at one tumour type over another."

Meanwhile, efforts are under way in Scotland to improve the rates of early lung cancer diagnosis.

A major 10-year screening trial has been launched to investigate if a new blood test could detect the disease months - or even years - earlier than it otherwise would be diagnosed.

It works by identifying levels of substances in the blood known as autoantibodies, which the body produces when cancer develops.

Lung cancer is also one of the priorities of a £30m Scottish Government campaign, which aims to increase the early detection of cancer by 25% by the end of 2015. It is being backed by football legend Alex Ferguson, who lost both his parents to the disease and has appeared in an advert encouraging people to get any symptoms checked.

Health Secretary Alex Neil said: "Lung cancer is the most common cancer in Scotland and that is why this Government is taking a range of measures to tackle it face on. It is a fact that more lives can be saved in Scotland through earlier detection."

The lack of funding for lung cancer research is also reflected in UK-wide figures, which show there is £3509 of research spend for every breast cancer death; £1531 for every bowel cancer death; but just £459 per lung cancer death.