If you were or currently are a smoker, you may be at higher risk of developing lung cancer than nonsmokers. If you are at high risk, you should know that you can now opt into lung cancer screening programs that look for cancers before you develop symptoms. Not everyone is eligible for screening, and eligibility varies by the guideline-producing organization. But deciding whether to undergo screening for lung cancer is a personal decision that should be made in conjunction with sound advice from your doctor.
Currently, various organizations including the U.S. Preventive Services Task Force, the American Cancer Society, the American Association for Thoracic Surgery, the American College of Chest Physicians and the National Comprehensive Cancer Network all have published screening guidelines that make slightly differing recommendations for who should be screened. Generally speaking, current or former heavy smokers between the ages of 55 and 80 should consider annual screening for lung cancer.
These guidelines were developed based on the results of the National Lung Cancer Screening Trial conducted between 2002 and 2011. That massive study of 53,454 current or former heavy smokers aged 55 to 74 compared low-dose helical computed tomography scanning, which is a form of low-dose radiation CT scanning, to chest X-rays. The study found that participants who received the low-dose CT scans had a 15 to 20 percent lower risk of dying from lung cancer than participants receiving standard chest X-rays.
The NLST findings were recently augmented by the results of the NELSON trial, a very large, randomized, population-based study conducted in the Netherlands and Belgium that assessed the value of low-dose CT screening in people at high risk of developing lung cancer. According to that study, overall, CT scanning (versus not screening at all) decreased mortality by 26 percent in high-risk men and up to 61 percent in high-risk women over a 10-year period. The findings were presented this past September at the International Association for the Study of Lung Cancer 19 th World Conference on Lung Cancer.
The findings add substantial evidence that screening should be more widely implemented, says Dr. Andrea B. McKee, chair of radiation oncology at Lahey Hospital and Medical Center‘s Sophia Gordon Cancer Center in Burlington, Massachusetts. “In the NELSON study, they screened over a longer period of time,” 10 years versus the 5-year timeline used for the NLST. Because of that, McKee says “it’s not surprising that they showed an even bigger mortality benefit than the NLST,” further supporting the notion that there’s a real benefit to screening for lung cancer among high-risk individuals.
However, as with any screening tool, there’s the possibility of harm to the patient, and it’s important that you understand what those harms are and how they could impact you before you decide to enroll in routine lung cancer screening.
Dr. Peter Mazzone, director of the lung cancer program at the Cleveland Clinic in Ohio, says there are three primary areas of concern in relation to harms: false positives, overdiagnosis and exposure to radiation.
False positives occur when the scan finds a nodule or other abnormality in the lungs that turns out not to be cancerous. “The majority of those nodules are not cancer,” Mazzone says. “They’re just benign scars or marks in the lung from breathing something in and living life. They’re nothing that will ever hurt a patient and most of those are small enough that they just get followed over time.”
Some of them may be more worrisome than others and result in additional testing. If they are then found not to be cancer, that’s considered a harm to the patient because the test wasn’t necessary. “Separately, if an individual comes in a little nervous about their chance of having lung cancer and they’re told they have a lung nodule, even though it’s likely to be benign, it can lead to distress and concern on the patient’s part,” which is another potential harm, Mazzone says.
McKee says there’s been some confusion and misinformation distributed recently about the false positive rate, with some reputable medical journals citing a false positive rate from lung cancer CT scans of 96 percent or higher. This is actually the false discovery rate, and “there’s a big difference,” between false discovery and false positives. This is a finer point of statistical analysis, but McKee says that in actuality, the false positive rate is less than 8 percent overall, depending on the program or study. “The false positive rate is 7.2 percent over the lifetime of our program,” and the NLST’s overall false positive rate was a little bit higher at 7.8 percent.
That said, the first screen you have — your baseline screen — is more likely to result in a false positive because the radiologist has nothing else to compare the image to and will likely follow up on anything that looks suspicious. In the NLST, baseline screens had a false positive rate of 12.6 percent, “but then on the additional rounds of screening, it goes down to 5 percent, so the overall rate is 7.8 percent,” McKee says.
Exposure to Radiation
Radiation is powerful energy that’s used both to find and cure cancer, but can also cause it in some cases. When radiation is used routinely for screening, that could potentially elevate your risk of developing cancer. “Most feel that the amount of radiation is very safe over time, but the potential for multiple scans with added radiation through the years could cause harm,” Mazzone says. “Radiation-related cancer is an example of something that we discuss with our patients, and most feel it’s a very small risk. But it’s something patients should know about.”
McKee agrees that radiation exposure should be discussed, but the dose of radiation administered by each scan is so low, it’s unlikely to be a problem. An analysis of her screening program at Lahey showed that each scan delivers 0.65 millisieverts of radiation to the body. At this level, if a patient were to receive three scans a year for 30 years, the patient would receive 58.5 mSv of radiation. “Myself as a radiation worker, I’m allowed to receive 50 mSv of radiation per year. So 58.5 mSv over 30 years is negligible or too small to measure,” she says.
“Overdiagnosis applies to people who actually have lung cancer,” McKee says, but these people die of something unrelated. Overdiagnosis often leads to overtreatment, meaning the patient undergoes surgical procedures or other treatments that are unnecessary to prolong life because the disease won’t cause issues during the patient’s ordinarily expected lifetime. “In general, lung cancer is such an aggressive cancer you’re less likely to have overdiagnosis,” she says, noting that the overdiagnosis rate in the NLST is often cited at 18 percent.
However, she says this figure includes bronchioloalveolar carcinomas, or BACs, which tend to be less aggressive cancers that show up on screening tests but aren’t likely to progress quickly. “We don’t act on BACs in screening unless they show signs that they’ve become aggressive,” but your doctor will follow these abnormalities in case they change. When those BACs are excluded from the data set, “the overdiagnosis rate is only 3 percent. But that’s not what you hear when people talk about it. You hear there’s an 18 percent chance that you’re going to get diagnosed,” and that can frighten some people away from getting screened because they’re simply too afraid to find out.
Listen, Ask Lots of Questions and Weigh the Pros and Cons
How patients are counseled about these potential harms varies from program to program, Mazzone says, but “there are recommendations from Medicare and in many of the guidelines that the benefits and harms of screening should be discussed in detail with patients to help them make a decision about care that fits with their values.” This takes place during what’s called a shared decision-making visit, and in most cases, that visit is mandated by the insurance company if it’s going to cover the cost of the scan.
When she meets with patients, McKee says she likens lung cancer screening to mammography for breast cancer, which is a more well-established screening tool that most people have some familiarity with. She also tells patients that “when we screen for lung cancer, we find it in earlier stages. About 85 percent of the time, it’s stage 1 or 2,” which are curable. Screened stage 1 lung cancer has about a 90 percent 5-year overall survival rate,” she says, which is “something most people don’t know. Most people think lung cancer is fatal,” because traditionally, lung cancer has been diagnosed at much later stages when it’s less treatable.
She also advises patients of the chances of finding a nodule that requires additional evaluation (about 10 percent or less). When discussing the chances of overdiagnosis, McKee says there’s about a 3 percent chance that will happen. “I tell them there’s a chance we may find something that would never have threatened your life, but it’s quite small.” Lastly, if the patient is still smoking, they talk about smoking cessation as the primary means of promoting lung health. Although “the lungs don’t forget that you smoked,” stopping smoking is the biggest thing you can do to reduce your risk of developing lung cancer and quitting provides a host of other health benefits.
The shared decision visit is also your chance to ask questions and talk over your individualized risks and benefits. If you’re not sure that screening is the right option for you, Mazzone recommends checking out the risk calculator at ShouldIScreen.com, which asks a series of questions to determine your individual risk level that may help you decide. He says that good counseling results in patients understanding well the potential benefits and harms of screening. “We want to make sure at the time of the visit that people gain enough knowledge,” but that “they haven’t been scared away by the harms.”
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In his program, Mazzone says only about 2 percent of patients decline screening after the shared decision-making visit. “It just turned out they didn’t think the balance was right for them, and I think that’s OK. Two percent is a small enough number that it’s not that the message was just too scary.” Rather these patients made an informed decision that fits their situation. “In the shared decision-making visit, we’re guiding and partnering with patients to make a decision that they feel fits with their value set.”
He adds that if you do opt for regular screening, it’s important to choose a “really high-quality screening program,” that offers not just the screening, but subsequent treatment and support. “Lung screening is an entire program, not just a scan. We have to make sure patients have the opportunity to have a shared decision-making visit before the scan and then have access to care after if something is found.” And providing high-level care is critical to improving survival rates from lung cancer no matter when and how it’s discovered.
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