At a glance
- Lung cancer is one of the few cancers with a well-defined etiology — inhalation of tobacco smoke.
- Patients at high risk for lung cancer should decide with their clinician whether or not to undergo regular screening.
- In the case of an abnormal chest x-ray, the patient should undergo a chest CT for further evaluation.
Lung cancer is the most common cause of cancer death in the United States. In this year alone, an estimated 174,470 new cases (92,700 among men and 81,770 among women) will be diagnosed. They will account for approximately 12% of all new cancer diagnoses, and not surprisingly, most cases will be found in former smokers.
The average age of a person diagnosed with lung cancer is 70, and the chance that a man will develop it is 1 in 13; in a woman, that risk is 1 in 17. These figures take into account all people and do not include smoking history.1 Among subgroups, African-American men experience the highest rates (31.3%), followed by white men (26.4%) and Hispanic men (25.0%). Among women, rates in whites and African Americans are similar (22.9% and 22.5%, respectively), whereas incidence among Hispanic women is significantly lower (12.7%). Overall, women comprise 40% of all lung cancer cases; the disease has surpassed breast cancer as the most common cause of female cancer death.2 Areas in which tobacco farming has been indigenous — such as Kentucky and West Virginia — have a higher incidence (32.2%). In states where smoking is less common, such as Utah, the prevalence is much lower at 17.1%.3
Environmental risk factors?
Lung cancer is one of the few cancers with a well-defined etiology — inhalation of tobacco smoke. In fact, smoking is responsible for 80%-90% of all cases.2 Cigarette smoke contains more than 4,000 different chemicals — many of which are proven carcinogens. Cigar and pipe smoke also increase the risk of lung cancer.
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In his June 2006 report, The Health Consequences of Involuntary Exposure to Tobacco Smoke, former U.S. Surgeon General Richard H. Carmona, MD, MPH, noted that even brief exposure to secondhand smoke can cause immediate harm.3
The second most common causative agent is radon, a colorless, odorless, radioactive gas that forms when radium decays. This element is responsible for approximately 12% of all lung cancer deaths annually — roughly 15,000 to 20,000 people. Exposure to asbestos, uranium, arsenic, and other petroleum-containing products also increases the risk for lung cancer.4
Radiologic screening
Currently, the American Cancer Society (ACS) does not recommend lung cancer screening for asymptomatic patients at risk for the disease.5 Symptomatic patients are often screened initially with chest x-ray; however, this testing modality is usually not sensitive enough to detect small tumors and overuse of x-rays can also be harmful. In the Early Lung Cancer Action Project, researchers detected 27 lung cancers by spiral CT scans; only seven of these were visible on chest x-ray.6 In a Japanese study, chest x-rays failed to detect 79% of lung cancers <2 cm.7
The ACS historically has maintained, however, that patients at high risk for lung cancer should decide on an individual basis with their clinician whether to undergo regular screening. The most accurate screening tool is low-dose helical CT, which has been found to be superior to x-ray at detecting small and presymptomatic lung cancers. However, to date, there is no evidence that supports a decrease in lung cancer mortality with routine radiological screening.8 The mind-boggling statistic that 60% of patients diagnosed with lung cancer will die within one year and that 75% will die within two years remains accurate—regardless of when in the disease process they are diagnosed.1
The clinician as the initial point of contact
The first person most patients see when they are experiencing physical problems is their primary-care clinician. As such, it is important that clinicians be on the lookout for patients who harbor hidden symptoms or may not be aware of a change in their health status.
Lung cancer may present with a variety of symptoms and is frequently masked by more common illnesses (Table 1). Many patients report no symptoms whatsoever, so it is essential that specific questions be asked to try to elicit information about symptoms they may not consider abnormal. Clinicians should inquire about frequency of cough, shortness of breath, presence of hemoptysis, chest and/or pleuritic pain, and change in weight/appetite, as these are the common features noted on presentation.9 However, because lung cancer is progressive, by the time patients exhibit clinical findings, they are likely to have advanced disease.
In the case of an abnormal chest x-ray, the patient should immediately undergo a chest CT for further evaluation. Figures 1 and 2 show abnormal chest CTs in patients who initially presented with weight loss and cough. A thorough laboratory evaluation, including complete blood count and full chemistry panel, including albumin and coagulation panel, should also be performed. Baseline pulmonary function tests will help determine if the patient should be considered for surgical resection, depending on the pathology of the cancer. Positron emission tomography will further clarify the extent of the cancer and any lymph-node involvement.
Once lung cancer is suspected, the patient should be referred to an oncologist, who will determine the most appropriate diagnostic procedure (e.g., sputum cytology, mediastinoscopy, bronchoscopy, or CT-guided lung biopsy) and most beneficial overall course of therapy for the patient’s individual needs.
After the diagnosis is made
The patient’s relationship with the primary-care clinician remains crucial even after diagnosis and referral. Although the oncologist will most likely take charge of treatment, the clinician still has an important role — whether it is providing emotional support or managing other disease processes that may develop or change during the course of cancer treatment. In addition, because the patient and his or her family are less familiar with the oncologist, they will be more likely to discuss day-to-day issues with the clinician.
In general, all follow-up x-rays and studies are ordered by the oncology/surgical-management team. However, health-maintenance and prevention strategies still need to be addressed by the primary-care clinician. This individual may also be expected to oversee acute medical issues that arise outside the therapeutic course of the patient’s underlying disease process. Finally, while many patients who develop lung cancer will quit smoking, there are patients who will continue the habit. It will be up to the clinician to provide any smoking-cessation counseling and program options.
It is impossible to know which patient is going to be the next one diagnosed with lung cancer, but clinicians can be certain that someone with this diagnosis will pass through their practice on a fairly regular basis. Therefore, it is important to be aware of the clinical symptoms frequently seen in patients who are diagnosed with lung cancer as well as to have a good working knowledge of the individual patient’s risk factors. If lung cancer is suspected, it is important to maintain frequent contact with the patient and emphasize the need for further evaluation and follow-up.
Finally, since most lung cancers are caused by smoking, patients should be told that the only safe cigarette is one that is not smoked. They should also be counseled to avoid places where people are smoking to eliminate added risks. This information cannot be emphasized enough.
Ms. Van Buskirk is an acute care nurse practitioner at the Veterans Affairs Pittsburgh Healthcare System in Pittsburgh.
References
1. American Cancer Society. Cancer Facts & Figures, 2006.
2. Pretreatment evaluation of non-small cell lung cancer. The American Thoracic Society and The European Respiratory Society. Am J Respir Crit Care Med. 1997:156:320-332.
3. United States Department of Health and Human Services. New Surgeon General’s Report Focuses on the Effects of Secondhand Smoke.
4. Halpern M, Gillespie B, Warner K. Patterns of absolute risk in lung cancer mortality in former smokers. J Natl Cancer Inst. 1993;85:457-464.
5. Smith RA, Cokkinides V, Eyre HJ. American Cancer Society guidelines for the early detection of cancer, 2003. CA Cancer J Clin. 2003;53:27-43.
6. Henschke C, McCauley D, Yankelevitz D, et al. Early Lung Cancer Action Project: overall design and findings from baseline screening. Lancet. 1999;354:99-105.
7. Sone S, Li F, Yang Z, et al. Characteristics of small lung cancers invisible on conventional chest radiography and detected by population based screening using spiral CT. Br J Radiol. 2000;73:137-145.
8. Kazerooni EA. Lung cancer screening. Eur Radiol. 2005;15 Suppl 4:D48-D51.
9. Gonzalez JM, de Castro FJ, Barrueco M, et al. Delays in the diagnosis of lung cancer. Arch Bronconeumol. 2003;39:437-441.
