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New Lung Cancer Screening Guidelines for Heavy Smokers
The American Cancer Society has published new guidelines that recommend physicians discuss lung cancer screening with patients who meet certain criteria that put them at high risk for developing the disease. Patients in this high-risk population are 55 to 74 years of age and in fairly good health; have a smoking history equivalent to a pack of cigarettes each day for 30 years; and currently smoke or have quit smoking within the past 15 years.
If patients agree to be screened, the recommendations specify that testing should be done with a low-dose computed tomography (CT) scan and should take place at a facility with experience in lung cancer screening. The recommendations also emphasize that screening is not a substitute for quitting smoking.
The new guidelines were published on January 11 in the online edition of CA: A Cancer Journal for Clinicians.
The recommendations are based on a review of several studies that looked at low-dose CT screening. The most significant of these studies was the National Lung Screening Trial (NLST). This study included more than 50,000 subjects aged 55 to 74 years who were current or former smokers with a smoking history equivalent to one pack a day for 30 years or two packs a day for 15 years. The NLST found that subjects who underwent low-dose CT had a 20% lower chance of dying from lung cancer than had those who received chest x-rays. However, other trials found no benefit from screening.
None of the studies included people who never smoked. Although nonsmokers can develop lung cancer, there is not enough evidence to know whether screening them would be helpful or harmful. Likewise, it isn’t known whether screening would help people who were lighter smokers than were those in the studies, or those of different ages.
The idea of screening for lung cancer is appealing, because it has the potential to find the cancer earlier, when it’s easier to treat. Screening is performed in people who do not have any symptoms of cancer. Lung cancer symptoms don’t usually appear until the cancer is already advanced and cannot be cured.
One drawback of low-dose CT scans is that they may detect abnormalities that turn out not to be cancer but that still need to be assessed. (About 25% of the subjects in the NLST had such a finding.) This may lead to additional scans or more invasive tests, such as needle biopsies or surgery to remove a portion of lung. There is also the risk that comes with increased exposure to radiation.
Because of these drawbacks, CT scans are not recommended for people who are less heavy smokers, or who are younger than 55 years or older than 74 years. Moreover, the procedure is not recommended for people who have serious diseases that limit their life expectancy. The new guidelines say that physicians should discuss all of the potential risks, benefits, and limitations of screening with patients who meet the high-risk criteria and help these patients make an informed decision about whether they should be screened. Screening is recommended every year through age 74, as long as the patient is healthy.
The guidelines also emphasize that screening for lung cancer is not a substitute for quitting smoking. The most important action anyone can take to reduce their risk of lung cancer is to not smoke or use any form of tobacco. Most cases of lung cancer occur in people who smoke or who used to smoke.
Besides lung cancer, tobacco use also increases the risk for cancers of the mouth, lips, nose, sinuses, larynx, throat, esophagus, stomach, pancreas, kidney, bladder, uterus, cervix, colon/rectum, and ovary, as well as the risk for acute myeloid leukemia. In the U.S., tobacco use is responsible for nearly one in five deaths; this equates to approximately 443,000 early deaths each year.
Source: American Cancer Society; January 11, 2013.