Lung cancer tests advised for some heavy smokers

New recommendations from chest and cancer doctors call for lung cancer screening in older adults with a long history of smoking a pack a day or more - but also highlight the possible harms of screening, including a high risk of false positive tests.

The guidelines are based on a review of past studies which compared long-term health in smokers who underwent low-dose CT screening for lung cancer and those who got another cancer test or "usual care" instead.

Most of the evidence in favor of screening comes from a single large study known as the National Lung Screening Trial. That study found a 20-percent lower risk of lung cancer death among more than 26,000 people screened with low-dose CT annually for three years, compared to those who were tested with so-called chest radiographs instead.

But the combined prior research also suggested that in any round of CT screening, about one in five people will have positive results that require further testing, sometimes with invasive procedures - although only one percent will actually have lung cancer.

"The trade-offs there are sizeable, even in the high-risk people," said Dr. Peter Bach, the lead author of the new review paper from Memorial Sloan-Kettering Cancer Center in New York.

"As you go down the risk range - younger people, people who have smoked less - because their chance of ever developing lung cancer is lower, the chance that they will benefit is also lower, and in some cases substantially lower," he told Reuters Health.

According to the new recommendations from the American College of Chest Physicians and the American Society of Clinical Oncology, annual screening should be offered to current and former smokers, age 55 to 74, who have smoked at least a pack of cigarettes a day for 30 years.

The screening recommendations don't apply to former smokers who quit more than 15 years ago, the researchers reported Sunday in the Journal of the American Medical Association.

Possible harms of lung cancer screening, they said, include the radiation associated with CT scans - which over long periods of time may increase the risk of cancer itself - as well as the unnecessary extra procedures and anxiety that come with a positive test that turns out to be a benign nodule.

Dr. James Mulshine, a lung cancer researcher at Rush Medical College in Chicago, said the new study may overplay the risks of screening compared to the benefits of catching potentially-deadly lung cancers early.

Currently, most lung cancers aren't caught until stage III or IV, and less than one in five people with a new diagnosis survives five years.

"Lung cancer screening is a big deal," Mulshine, also the vice president for research at Rush, told Reuters Health.

"Some people potentially will be harmed, and there's even the chance some people will die (because of complications from screening). But that's also the case of flu shots… and driving to the doctor's office."