Alberta Cancer Foundation

Catch it Early

It’s the leading cause of cancer-related death in Canada, killing more people than prostate, breast and colon cancer combined. “There are more deaths from lung cancer than any other cancer,” says Dr. Paul MacEachern, a respirologist who knows firsthand how deadly the disease is. Much of the Calgary doctor’s day-to-day work is spent evaluating patients with masses in their lungs. MacEachern sees patients who are referred to him because they’ve had abnormal CT scans or chest X-rays. He frequently diagnoses patients with lung cancer before referring them to the Tom Baker Cancer Centre for treatment.

The survival rates for people diagnosed with lung cancer are low, because most people are diagnosed too late. “The majority of people who present with lung cancer, present at a stage where it’s already advanced,” explains MacEachern over the phone from a hotel room in Atlanta where he’s attending a lung conference. Because people show symptoms after the cancer has progressed, the early detection and treatment of lung cancer is the most promising strategy to reduce mortality from the disease. “It’s very attractive to think, ‘Well if we can just catch these lung cancers early, then we can save lives.’ ” MacEachern says. Unfortunately, it isn’t that easy.

There is currently no screening program for lung cancer in Alberta. Until quite recently, there was no evidence to suggest that screening worked. In the fall of 2011, a U.S. study, the “National Lung Screening Trial,” demonstrated that lung cancer screening with a CT scan had the potential to save lives and reduce mortality for lung cancer. “That was big news because we’ve never had a screening test for lung cancer before,” MacEachern says. While the new study was exciting and seemed promising, it left doctors like MacEachern wondering how to move forward with the information without putting a strain on the medical system.

There is currently no screening program for lung cancer in Alberta. Until quite recently there was no evidence to suggest that screening worked.

“The reason people aren’t automatically jumping on this is because screening is a process, not just one test,” says MacEachern, adding that resources need to be put into place to properly screen patients for lung cancer. The screening test that would be used, if a lung cancer screening program were to be introduced in the future, is a simple low dose CT scan that aims to minimize radiation exposure. Yet, giving a CT scan to thousands of people is no easy feat. “The magnitude of people that need to be screened is huge in the sense of the workload it could potentially generate,” says MacEachern. If everybody in Alberta who was potentially eligible for screening were to be screened, the workload in terms of the sheer number of CT scans would very quickly overwhelm the health-care system and the surgeons and radiologists who work in it, MacEachern says.

Another problem with blanket screening is that the rate of detection of nodules that turn out to be nothing is high. About 20 per cent of people screened will have an abnormality, usually a nodule in the lung. Of these nodules, more than 95 per cent are benign. Unfortunately the CT scan does not show which nodules will turn out to be cancer, leading to followup testing and investigation of all nodules. This leads to anxiety and worry for people being screened, extra tests such as followup CT scans, and occasionally invasive procedures such as biopsies or surgeries and the attendant risk of complications associated with the procedures.

If a screening program were introduced, the ideal candidates for screening would be those with the highest risk of lung cancer. Factors that increase the risk of lung cancer include age and smoking and, as such, MacEachern says the best candidates would be people aged 55 to 75 with a history of heavy smoking. “If we’re going to implement screening, we have to take our time and make sure it’s done right; otherwise the potential for harm is greater,” he says.

As doctors like MacEachern evaluate how a lung cancer screening program should be implemented across the province in a widespread fashion, Canadians across the country are participating in a lung cancer detection study that recognizes the need to create a lung cancer screening program. The Terry Fox Research Institute and the Canadian Partnership Against Cancer are undertaking an early lung cancer detection study. MacEachern notes Calgary is one of seven sites across the country participating in the study and about 250 Calgarians make up the study’s 2,500 participants. “The main purpose of the study was to try and validate the risk prediction model. Is there some way we can predict better who is at risk for lung cancer that would allow us to then hopefully be able to screen fewer people but to catch most of the lung cancers?” he asks. The study is nearing completion. All participants have had scans and are now in followup stages while data is collected.

The study screened current and former smokers between 50 to 75 years of age at high risk of lung cancer. Through the data gathered, the study aims to track the type of diagnostic tests and treatment, as well as their costs, thus determining the health-care resources required and how much it would cost the public if a lung cancer screening program were to be implemented across the country. A primary objective of the study, which has brought together experts in radiology, respiratory medicine, thoracic surgery, pathology, oncology, epidemiology, health economics and health-care policy, is to find an effective way to identify lung cancer in its early stages, thus increasing survival rates.

Whether we can implement lung cancer screening across the province, or from coast to coast, is still in question. “It’s exciting in a way because we’ve never had a screening test for lung cancer and it does have the potential to save lives,” MacEachern says, adding: “The excitement is tempered by the fact the magnitude of the problem is huge.” As Canada’s deadliest cancer continues to take lives, MacEachern says it’s imperative that in the future, the right people get screened for lung cancer, in the right fashion. “People get excited about screening and there is reason to get excited. It has significant potential,” he says. “I just want to stress that it’s going to take some time before we can implement this. We’d like to try to implement something because there is benefit to Albertans if we do so, but there are potential harms and we have to make sure we do it right to minimize the harms and maximize the benefits.”

Despite the potential risks involved with screening for lung cancer, MacEachern stresses, “A screening program should not be considered a substitute for a tobacco control program. The best way to reduce your chance of getting lung cancer is to quit smoking or never start smoking.”