Surgical Innovations

Lung Cancer Screening and Assessment

Navigating confusion and controversy about CT screening for lung cancer

The CT image (top) shows a mass in the left lung. The combined PET/CT image (below) reveals the metabolic activity of that mass, as well as its precise location in the lung.

Detecting a disease in its early stages usually leads to a better chance of successfully treating it. So should we all go out and have ourselves screened for lung cancer just to be on the safe side?

Well, not necessarily. The question is actually complex and controversial, according to Charles A. Powell, MD, Medical Director, Lung Assessment Program and Assistant Professor of Clinical Medicine, Division of Pulmonary and Critical Care Medicine.

The public may be confused by mixed messages regarding screening for lung cancer, as are many physicians, according to Dr. Powell. While there are strong advocates of computed tomography (CT) screening for lung cancer, the American Cancer Society does not recommend screening as a routine test.

The challenge facing patients and their physicians lies in the fact that there is a good chance that a nodule will be found in the lungs, especially in patients over 55 with a history of smoking. In most cases, the nodules are eventually determined to be harmless—but many patients will experience weeks or months of anxiety until a diagnosis is established. At this time, imaging technology cannot reliably distinguish cancerous from non-cancerous nodules. In addition, differences in the ways that physicians manage the care of patients with nodules can make the follow-up process very challenging for both patients and their physicians.

Moreover, adding to the confusion is research showing that detecting cancerous nodules early may or may not save lives. "CT screening may preferentially detect early stage tumors that are relatively inactive, which is analogous to the situation in prostate cancer," says Dr. Powell. It may seem counterintuitive, but in the case of lung cancer screening, studies have found that even though more lung cancers were detected when patients were screened (versus not screened), long-term mortality rates were not affected by the discovery of those tumors.

On the other hand, Dr. Powell notes, it is not uncommon for a patient to have a CT scan for another reason that detects a lung tumor incidentally. Because some tumors do spread and become deadly, assessment and monitoring of any suspicious lesion is critical. Abnormalities must be monitored diligently, according to Dr. Powell, so that lesions requiring intervention can be treated earlier rather than later. The High-Risk Lung Assessment Program at NewYork-Presbyterian Hospital/Columbia University Medical Center has established a highly refined process to do this in a very efficient manner.

Dr. Powell recommends consideration of CT screening for people who have a high risk of lung cancer based on family history, health, and smoking history. For those with a moderate risk, thorough discussion of the potential results of a scan and follow-up options is essential before deciding upon screening. He believes that it is very important to guide patients regarding screening on an individual basis, taking into account each person's health, symptoms, family history, and very importantly, how he or she would cope with the discovery of a nodule, should one be found. "Finding a nodule can affect a person's quality of life," Dr. Powell says. "Some people can handle the uncertainty associated with an undiagnosed pulmonary nodule, while others have more difficulty," he explains.

Risk factors for lung cancer

The risk factors for lung cancer are both genetic and environmental, based on exposure to toxins and carcinogens. Lung cancer most often strikes people over age 50 who have a history of smoking. Even for smokers, however, screening for lung cancer is not a routine healthcare measure, and is not usually covered by insurance if a person has no symptoms.

Among healthy former smokers over age 55, screening will detect a nodule in 25- 40% of people. When nodules are found, a process follows to distinguish which may be benign and which may be cancerous; only 1.5-2% of nodules are likely to be cancerous, according to Dr. Powell.

To determine whether a nodule is benign or cancerous, information about the nodule itself and the patient's health history are both evaluated. Nodule properties such as size, shape, patterns of irregularity, calcification, and changes in size or shape over time are observed. Overall health factors, including general health, exposure to smoke and toxins, family history, and other factors are also considered. Together, these data are processed to determine whether the individual's nodules have a low, intermediate, or high probability of being cancerous. The determination of risk is then used to guide treatment decisions.

The Columbia High-Risk Lung Assessment Program

The Columbia High-Risk Lung Assessment Program uses an algorithm-driven approach to provide comprehensive, thorough care to two groups of patients. The first group, the "well at risk," includes those at risk for pulmonary disease due to family history or environmental exposures. The program helps to define the risk each patient faces, mitigates risk factors (for example by referring smokers to innovative smoking cessation programs at Columbia), conducts further screening through lung function tests, or orders additional CT scans or imaging tests as required. This group of "well at risk" patients includes many New York firefighters who responded to the attack on 9/11, as well as people who have been exposed to chemicals, paint, or other toxic substances.

The second group targeted by the program includes people who have begun a screening protocol, or who have been found to have an abnormality on a CT scan. For these patients, the program uses the best available evidence to manage the results of screenings and to provide comprehensive follow-up care.

For low-risk nodules, the Lung Assessment Program typically recommends follow- up imaging at algorithm-specified intervals. For intermediate lesions, the team uses other tools to try to refine the probability of malignancy. One is to follow the lesion over time, because malignant nodules tend to grow, whereas benign ones do not. Sequential CT scans at three-month intervals may be recommended to monitor for signs of change. Another strategy is to use PET/CT scanning to determine whether a nodule may be metabolically active, because malignant lesions tend to be metabolically active while benign nodules do not.

If a lesion is highly likely to be cancerous, the program may recommend biopsy or removal of the lesion. In most cases, the program uses minimally invasive surgical methods. For those patients with lung cancer, the program uses endobronchial ultrasound, which provides sophisticated staging of the lesions. A new device called opto-electronic plethysmography now allows the program to very easily and noninvasively evaluate lung function in each portion of the lung. In addition, the program includes thoracic oncology evaluation for consideration of chemotherapy when appropriate.

Patients may be referred by a primary care physician or pulmonologist, or they may seek evaluation on their own.