Current and former smokers between the ages of 55 and 74, who are at high risk of developing lung cancer, should be screened annually for up to three years with low-dose CT scans, the Canadian Task Force on Preventive Health Care says.

The new guideline was published in the Canadian Medical Association Journal on Monday.

It applies to current smokers, or those who have quit within the past 15 years, with a "30 pack-year history." That means smoking a pack per day for 30 years, or two packs per day for 15 years. The screening with low-dose computer tomography must be done in a health care setting with expertise in diagnosing and treating lung cancer, the task force says.

The group does not recommend lung cancer screening for all other adults, regardless of their age or smoking history. It also recommends that health care professionals don’t use chest X-rays to screen for lung cancer.

The new recommendations are similar to guidelines already used by Cancer Care Ontario and several U.S. organizations, including the American Cancer Society and the American Lung Association. There are currently no organized lung cancer screening programs across Canada.

“Screening for lung cancer aims to detect disease at an earlier stage, when it may respond better to treatment and be less likely to cause serious illness or death,” Dr. Gabriela Lewin, chair of the Canadian Task Force on Preventive Health Care guideline working group, said in a news release.

Lung cancer is the most common cancer in Canada and the number one cause of deaths from cancer. In 2015, approximately 26,600 Canadians were diagnosed with lung cancer, and almost 21,000 died from it, the task force says.

About 85 per cent of lung cancer cases are linked to tobacco smoking.

Dr. Heather Bryant, vice president of cancer control at the Canadian Partnership Against Cancer, told CTV News that the new guideline is aimed at identifying people “at substantially high risk” and offering them a screening tool. The screening test is not for people who smoked “for a couple of years as teenagers,” she said.

Dr. Christian Finlay, a thoracic surgeon at St. Joseph’s Healthcare in Hamilton, Ont., said between 18 and 20 per cent of lung cancer patients he sees have treatable disease – a rate he called “tragic.”

The Canadian Task Force on Preventive Health Care hopes that its new guidelines will help doctors catch more lung cancers at earlier stages, before they become incurable.

Kathy Kernohan believes a CT scan she underwent as part of a screening study in Toronto in 2004 saved her life. She was a former smoker who quit. But when she had the scan, doctors found a small tumour.    

“I am forever thankful for that,” said the now 72-year-old Kernohan.

“They found my cancer early and I got treatment…and here I am…many years later.”   She fully endorses the new task force guidelines.

The new recommendations don’t apply to people with a family history of lung cancer or those who show symptoms of the disease. The task force says it is not known whether CT screening for people with other risk factors for lung cancer –such as exposure to radon and second-hand smoke --- would be beneficial.

Physicians should talk to their high-risk patients about their screening preferences, the group says.

According to a 2015 report on tobacco use in Canada, approximately 4.2 million, or 14.6 per cent, of Canadians smoked in 2013.

Sixty-four per cent of Canadians who have ever smoked said they quit. Approximatelytwo-thirds of the remaining smokers said they were seriously considering quitting in the next six months.

With files from CTV’s medical specialist Avis Favaro and Elizabeth St. Philip