The American Cancer Society says that doctors with access to high-tech lung cancer screening equipment, as well as treatment centers, should talk to their healthy patients who have been smoking heavily for at least three decades about having their lungs checked.
The Society added that even ex-smokers who gave up less than 15 years ago and smoked heavily for over thirty years should be advised to undergo screening.
According to the guidelines, doctors should tell their patients what the benefits and known harms linked to lung cancer screening are.
The American Cancer Society says that it came to this conclusion after a panel of experts reviewed a number of cancer screening studies that were published in academic journals over the last few decades.
Guidelines published in JAMA in May 2012 recommended that older, current and former heavy smokers should receive annual low-dose CT screening of their lungs.
What are the benefits and harms of lung cancer screening?The authors of the latest guidelines say that the NLST (National Lung Screening Trial), which was published last year, strongly influenced their conclusions. The NLST involved 53,454 healthy males and females aged at least 55 years who were deemed at high risk of lung cancer because of their smoking history.
Half of them were assigned to the test group of low-dose spiral CT scan, while the other half, the "control group", underwent the standard single view chest X-ray. They were screened three times over a 24-month period. The researchers then checked to see how many were alive five to seven years later and assessed them.
Among those who had undergone the CT scans there were 356 lung cancer deaths, versus 443 deaths in the X-ray control group. The difference of 87 lives saved is a "statistically significant" number - a 20% drop in lung cancer death risk for those in the CT scan group.
The American Cancer Society wrote "One way of looking at this is: among about 27,000 people screened with a CT scan, 87 lung cancer deaths were prevented, but 356 lung cancer deaths still occurred."
Well designed clinical trials, such as the NLST one, help experts decide whether the benefits of screening outweigh the harms. The authors of the latest guidelines say that among healthy long-term heavy smokers or ex-smokers, the benefits of CT screening definitely outweigh the possible harms.
The experts wrote "A screening recommendation should only be made when the benefit clearly justifies the risk of harm."
What are the harms of screening? - despite the obvious benefits, the harms of screening must not be overlooked. Nearly 27,000 people underwent the 3-CT scans, of whom 40% had abnormal findings. They consequently had additional diagnostic tests, ranging from further CT scans to more invasive bronchoscopy, where a tube is placed down their throat into the lungs (via the mouth). Some of them underwent biopsies of the lung, an even more invasive procedure. The vast majority of the additional tests - 95% of them - did not result in a cancer diagnosis.
Sixteen patients who had received CT screening died within two months after an invasive diagnostic procedure that was carried out after their abnormal finding. Six of these 16 patients who died did not have lung cancer.
Even though nobody knows whether their deaths might have been caused by their invasive diagnostic procedures, the authors say that it reminds us that abnormal screening results can sometimes lead to dangerous diagnostic tests.
The NLST appears to show that for every five to six lives saved from CT-scan lung screening, one was lost because of the additional diagnostic procedures that an abnormal result caused.
Lung cancer screenings should be carried out in centers of excellence with experienced and well trained staff, so that the number of false positive screenings and extra invasive diagnostic tests are kept to a minimum, the Society added.
Lung cancer screening benefit for highest risk peopleLung cancer screening has the most benefit for healthy people at highest risk - those aged 55+ years with a long-term history of heavy smoking.
Lifetime non-smokers, or people with a history of light smoking do have a lung cancer risk, but the risk is not high enough to benefit from routine screening after the age of 55 - for them, the risk of harms from lung cancer screening is greater than the benefits.
The patient needs to make an informed decisionThe American Cancer Society says that patients and health care professionals need to know about the benefits, limitations and harms associated with a screening test. Screening tests have limitations and may be linked to possible harms.
Examples of limitations include anxiety, worry, the inconvenience involved in further testing, and the complications and potentially life-threatening risks linked to some diagnostic tests that occur after a false-positive result.
There is concern that modern technology can detect small tumors that are no threat to the patient, even though they are technically cancerous tumors.
"Overdiagnosing" tumors can result in unnecessary procedures and treatments, which themselves raise the risk of complications and pointless discomfort and pain for the patient. In some cases patients' lives may be put at risk.
For doctors and people in the medical profession, keeping these "overdiagnosis" numbers down to a minimum is crucial.
In an online communiqué, the American Cancer Society wrote:
"Still, for the group of people at high risk, the benefit of screening may outweigh the potential risks. If you fall into that group, tell your health care professional about your smoking history so he or she can begin a conversation with you about lung cancer screening."