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Blood test offers hope for earlier lung cancer diagnosis

Lung cancer is one of the most deadly cancers facing Canadians. A new early diagnostic test may help doctors detect the cancer before it's too late, researchers hope.
A Chinese doctor browses CT scans of lung cancer patients. Scottish researchers wanted to see if combining a blood test followed by X-ray and CT scans could identify patients at high risk. (Andy Wong/Associated Press)

The Canadian Cancer Society says lung cancer is the most common types of cancer in Canada. It's also the most deadly. New research presented Monday in Barcelona at the World Conference on Lung Cancer offers hope of earlier diagnosis and a greater opportunity to cure the disease.   

The test is called the EarlyCDT-Lung Test, and it's manufactured and distributed by Oncimmune. It's a blood test that measures the levels of seven antibodies that could be associated with the body's response to lung cancer. It can detect all types of lung cancer at all stages from stage I to stage IV. The test has been studied in more than 25 peer-reviewed clinical publications and has been tested on more than 120,000 tissue samples from patients.

A negative EarlyCDT-Lung Test means doctors are 90 per cent certain you don't have lung cancer. CT scans are more sensitive at correctly spotting disease but less specific than the blood test at correctly identifying those without disease. The hope is that the blood test used in combination with a CT scan of the chest can enable doctors to detect lung cancer at a much earlier stage when it's more likely to be cured.  

Dr. Frank Sullivan and colleagues from the University of St. Andrews in Scotland wanted to see if the EarlyCDT-Lung Test followed by X-ray and CT scans could identify patients at high risk of lung cancer and thus increase early detection.

Scotland has one of the highest rates of lung cancer in the world. The researchers recruited about 12,000 participants aged 50 to 75 years at high risk of developing the disease. Half got EarlyCDT-Lung Testing followed by a chest X-rays and a chest CT scan if they tested positive and every six months for up to two years, and half got standard care.

The researchers found 127 lung cancers (56 in the intervention group and 71 in the control arm). Of the cancers detected in the intervention group, significantly more of them were detected at an earlier stage when they were more likely to be curable.

The study is important because lung cancer is both common and deadly.That's true even though rates of smoking have been trending down.

It may be surprising to some, but non-smokers can get lung cancer. In the U.S, as many as one in five who die from lung cancer have never smoked or used tobacco. If lung cancer in non-smokers had its own separate category, it would rank among the top 10 most lethal cancers, according to the American Cancer Society.

CT scans for those at high-risk

Lung cancer is often diagnosed too late, and the best hope to lower the death rate is through early detection. We no longer screen the entire population with annual chest X-rays because studies found that they don't avert bad outcomes.

The EarlyCDT-Lung test is a promising approach because it identifies that smaller subset of patients at increased risk of dying from lung cancer. Once identified, the hope is that doctors will be able to follow them quite closely. Other studies have validated the blood test.

The Scottish study was not large enough to detect a difference in mortality after two years. However, the researchers plan on continuing to follow study participants for five years to see if the intervention group has a lower mortality rate. The conference findings haven't been published in a journal, where it would be vetted by other experts.

Canadian researchers have participated in at least one validation study of the EarlyCDT-Lung Test. The test is commercially available in the United Kingdom, Germany, China and the U.S. To my knowledge, there is no Canadian distributor.

The Canadian Task Force on Preventive Health Care strongly recommends that lung cancer screening programs offer support to help people quit smoking. (Sue Ogrocki/Associated Press)

The Canadian Cancer Society says that periodic screening of patients at high risk of lung cancer with low-dose CT scans of the chest detects lung cancer before symptoms appear. At present, there are no provincial or territorial screening programs for lung cancer. The Canadian Task Force on Preventive Health Care recommends screening for lung cancer with low-dose CT scans for adults at risk of lung cancer. Some provinces have begun pilot screening programs with the aim of starting a formal program down the road.

The Canadian Task Force on Preventive Health Care recommends screening for lung cancer with low-dose CT once each year for three years in adults who are 50 to 74 years of age who are current smokers or former smokers who quit in the last 15 years or have smoked 30 pack-years, which is defined as a pack per day for at least 30 years (or 2 packs per day for 15 years). The 50- to 74-year age range was recommended because screening is most effective in that age group.

The task force strongly recommends that screening programs offer support to help people quit smoking. That's because smoking makes many cancer treatments less effective, and because smokers have a higher risk of complications and death than non-smokers.

Not smoking is the best way to lower your risk of getting lung cancer and dying from it.

About the Author

Dr. Brian Goldman is a veteran ER physician and an award-winning medical reporter. As host of CBC Radio’s White Coat, Black Art, he uses his proven knack for making sense of medical bafflegab to show listeners what really goes on at hospitals and clinics. He is the author of The Night Shift and The Power of Kindness: Why Empathy is Essential in Everyday Life.

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