Lung cancer
Screening
Practice guidelines
Clinical practice guidelines issued by the American College of Chest Physicians in 2007 recommended against routine screening for lung cancer because of a lack of evidence that such screening was effective.[1]
In 2004, a clinical practice guideline by the U.S. Preventive Services Task Force (USPSTF) gave a grade I recommendation indicating that "the evidence is insufficient to recommend for or against screening asymptomatic persons for lung cancer".[2][3]
Studies of efficacy
Regular chest radiography and sputum examination programs were not effective in reducing mortality from lung cancer.[4] Previous studies (Mayo Lung Project and Czechoslovakia lung cancer screening study, combining over 17,000 smokers) had shown that early detection of lung cancer was possible with such programs, but mortality was not improved. Simply detecting a tumor at an earlier stage may not necessarily lead to improved survival. For example, plain chest X-ray screening resulted in increased time from diagnosis of cancer until death and those cancers being detected by screening tended to be earlier stages. However, these patients continued to die at the same rate as those who are not screened. At present, no professional or specialty organization advocates screening for lung cancer outside of clinical trials.
A computed tomography (CT) scan can uncover tumors not yet visible on an X-ray. CT scanning is now being actively evaluated as a screening tool for lung cancer in high risk patients, and it is showing promising results. The United States National Cancer Institute is currently completing a randomized trial comparing CT scans with chest radiographs. with results expected in 2010. Several single-institution trials are ongoing around the world.
The International Early Lung Cancer Action Project published the results of CT screening on over 31,000 high-risk patients in late 2006 in the New England Journal of Medicine.[5] In this study, 85% of the 484 detected lung cancers were stage I and thus highly treatable. Mathematically these stage I patients would have an expected 10-year survival of 88%. However, there was no randomization of patients (all received CT scans and there was no comparison group receiving only x-rays) and the patients were not actually followed out to 10 years post detection (the median followup was 40 months). Additional controversy surrounded the study after a 2008 New York Times report found that it had been funded indirectly by the parent company of the Liggett Group, a tobacco company; the use of tobacco industry funds was not disclosed in the paper.[6]
In contrast, a March 2007 study in the Journal of the American Medical Association (JAMA) found no mortality benefit from CT-based lung cancer screening.[7] 3,200 current or former smokers were screened for 4 years and offered 3 or 4 CT scans. Lung cancer diagnoses were 3 times as high, and surgeries were 10 times as high, as predicted by a model, but there were no significant differences between observed and expected numbers of advanced cancers or deaths.[8]
Randomized controlled studies are underway in this area to see if decreased long-term mortality can be directly observed from CT screening.[9]
Diagnosis
Solitary pulmonary nodule
A clinical prediction rule can help guide assessment.[10] On online version of this calculator is available at http://www.nucmed.com/nucmed/SPN_Risk_Calculator.aspx.
Nodules stable over two years time are likely to be benign (but not always).[11][12] The doubling time for a cancer (a double in volume is a 25% increase in diameter) is usually less than 2 years. The mean doubling time for malignant nodules with a ground glass appearance is 813 days.[11]
Regarding diagnostic imaging, metanalyses of positron-emission computed tomography (PET Scan) with 18-Fluorodeoxyglucose (18F-FDG) report:
- sensitivity = 97%[13]to 95%[14]
- specificity = 78%[13]to 82%[14]
For dynamic spiral computed tomography:[14]
- sensitivity = 93%
- specificity = 80%
A clinical practice guideline[15] by the American College of Chest Physicians, with accompanying systematic review[12], recommends computed tomography, with dynamic images if available.
References
- ↑ Alberts WM (2007). "Diagnosis and Management of Lung Cancer Executive Summary: ACCP Evidence-Based Clinical Practice Guidelines (2nd Edition)" 132 (3_suppl): 1S–19S. DOI:10.1378/chest.07-1860. PMID 17873156. Research Blogging.
- ↑ U.S. Preventive Services Task Force (2004). "Lung cancer screening: recommendation statement". Ann. Intern. Med. 140 (9): 738-9. PMID 15126258. [e]
- ↑ Humphrey LL, Teutsch S, Johnson M (2004). "Lung cancer screening with sputum cytologic examination, chest radiography, and computed tomography: an update for the U.S. Preventive Services Task Force". Ann. Intern. Med. 140 (9): 740-53. PMID 15126259. [e]
- ↑ Manser RL, Irving LB, Stone C, Byrnes G, Abramson M, Campbell D (2004). "Screening for lung cancer". Cochrane database of systematic reviews (Online) (1): CD001991. DOI:10.1002/14651858.CD001991.pub2. PMID 14973979. Research Blogging.
- ↑ Henschke CI, Yankelevitz DF, Libby DM, Pasmantier MW, Smith JP, Miettinen OS (2006). "Survival of patients with stage I lung cancer detected on CT screening". N. Engl. J. Med. 355 (17): 1763-71. DOI:10.1056/NEJMoa060476. PMID 17065637. Research Blogging.
- ↑ Cigarette Company Paid for Lung Cancer Study, by Gardiner Harris. Published in the New York Times on March 26 2008. Accessed March 26 2008.
- ↑ Bach PB, Jett JR, Pastorino U, Tockman MS, Swensen SJ, Begg CB (2007). "Computed tomography screening and lung cancer outcomes". JAMA 297 (9): 953-61. DOI:10.1001/jama.297.9.953. PMID 17341709. Research Blogging.
- ↑ Crestanello JA, Allen MS, Jett J, Cassivi SD, et al. (2004). "Thoracic surgical operations in patients enrolled in a computed tomographic screening trial". Journal of Thoracic and Cardiovascular Surgery 128 (2): 254-259. PMID 15282462.
- ↑ Gohagan JK, Marcus PM, Fagerstrom RM, et al (2005). "Final results of the Lung Screening Study, a randomized feasibility study of spiral CT versus chest X-ray screening for lung cancer". Lung Cancer 47 (1): 9-15. DOI:10.1016/j.lungcan.2004.06.007. PMID 15603850. Research Blogging.
- ↑ Swensen SJ, Silverstein MD, Ilstrup DM, Schleck CD, Edell ES (April 1997). "The probability of malignancy in solitary pulmonary nodules. Application to small radiologically indeterminate nodules". Arch. Intern. Med. 157 (8): 849–55. PMID 9129544. [e]
- ↑ 11.0 11.1 Hasegawa M, Sone S, Takashima S, et al (December 2000). "Growth rate of small lung cancers detected on mass CT screening". Br J Radiol 73 (876): 1252–9. PMID 11205667. [e]
- ↑ 12.0 12.1 Wahidi MM, Govert JA, Goudar RK, Gould MK, McCrory DC (September 2007). "Evidence for the treatment of patients with pulmonary nodules: when is it lung cancer?: ACCP evidence-based clinical practice guidelines (2nd edition)". Chest 132 (3 Suppl): 94S–107S. DOI:10.1378/chest.07-1352. PMID 17873163. Research Blogging.
- ↑ 13.0 13.1 Gould MK, Maclean CC, Kuschner WG, Rydzak CE, Owens DK (February 2001). "Accuracy of positron emission tomography for diagnosis of pulmonary nodules and mass lesions: a meta-analysis". JAMA 285 (7): 914–24. PMID 11180735. [e] ACPJC Review
- ↑ 14.0 14.1 14.2 Cronin P, Dwamena BA, Kelly AM, Carlos RC (March 2008). "Solitary pulmonary nodules: meta-analytic comparison of cross-sectional imaging modalities for diagnosis of malignancy". Radiology 246 (3): 772–82. DOI:10.1148/radiol.2463062148. PMID 18235105. Research Blogging. ACPJC Review
- ↑ Gould MK, Fletcher J, Iannettoni MD, et al (September 2007). "Evaluation of patients with pulmonary nodules: when is it lung cancer?: ACCP evidence-based clinical practice guidelines (2nd edition)". Chest 132 (3 Suppl): 108S–130S. DOI:10.1378/chest.07-1353. PMID 17873164. Research Blogging.