What is the best approach to a solitary pulmonary nodule identified by chest x-ray?

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Clinical Inquiries

What is the best approach to a solitary pulmonary nodule identified by chest x-ray?

J Fam Pract. 2007 October;56(10):845-847

By

Timothy F Mott, MD

Cheryl Goodwin, MLS

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References

1. Gould MK, Sanders GD, Barnett PG, et al. Cost-effectiveness of alternative management strategies for patients with solitary pulmonary nodules. Ann Intern Med 2003;138:724-735.

2. Tan BB, Flaherty KR, Kazerooni EA, Iannettoni MD. The solitary pulmonary nodule. Chest 2003;123(1 suppl):89S-96S.

3. Hood RT, Good CA, Clagett OT, McDonald JR. Solitary circumscribed lesions of lung: study of 156 cases in which resection was performed. JAMA 1953;152:1175-1181.

4. Good CA, Hood RT, McDonald JR. Significance of solitary mass in lung. AJR Am J Roentgenol 1953;70:543-554.

5. Good CA. Management of patient with solitary mass in lung. Chic Med Soc Bull 1953;55:893-896.

6. Good CA, Wilson TW. The solitary circumscribed pulmonary nodule: study of 705 cases encountered roentgenologically in a period of three and one-half years. JAMA 1958;166:210-215.

7. Yankelevitz DF, Henschke CI. Does 2-year stability imply that pulmonary nodules are benign? AJR Am J Roentgenol 1997;168:325-328.

8. Berger WG, Erly WK, Krupinski EA, Standen JR, Stern RG. The solitary pulmonary nodule on chest radiography: can we really tell if the nodule is calcified? AJR Am J Roentgenol 2001;176:201-204.

9. Swensen SG, Silverstein MD, Ilstrup DM, Schleck CD, Edell ES. The probability of malignancy in solitary pulmonary nodules: application to small radiographically intermediate nodules. Arch Intern Med 1997;157:849-855.

10. Gurney JW. Probability of malignancy in SPN [Web page]. Available at: www.chestx-ray.com/SPN/ SPNProb.html. Accessed on September 7, 2007.

11. Li F, Aoyama M, Shiraishi J, et al. Radiologists’ performance for differentiating benign from malignant lung nodules on high-resolution CT using computer-estimated likelihood of malignancy. AJR Am J Roentgenol 2004;183:1209-1215.

12. Shah SK, McNitt-Gray MF, De Zoysa KR, et al. Solitary pulmonary nodule diagnosis on CT: results of an observer study. Acad Radiol 2005;12:496-501.

13. Matsuki Y, Nakamura K, Watanabe H, Aoki T, et al. Usefulness of an artificial neural network for differentiating benign from malignant pulmonary nodules on high-resolution CT: evaluation with receiver operating characteristic analysis. AJR Am J Roentgenol 2002;178:657-663.

14. Gould MK, Maclean CC, Kuschner WG, Rydzak CE, Owens DK. Accuracy of positron emission tomography for diagnosis of pulmonary nodules and mass lesions: a meta-analysis. JAMA 2001;285:914-924.

15. Schreiber G, McCrory DC. Performance characteristics of different modalities for diagnosis of suspected lung cancer. Chest 2003;123:115S-128S.

EVIDENCE-BASED ANSWER

Your initial risk assessment should include the patient’s smoking history, advancing age, cancer history, and chest radiography features (strength of recommendation [SOR]: A, based on a validated clinical decision rule). You’ll also need to review old chest radiographs (SOR: C, based on expert opinion). A solitary pulmonary nodule unchanged for >2 years on chest radiograph or containing benign central calcifications requires no further work-up (SOR: B, based on historical cohort studies).

While radiologists’ interpretations of a nodule’s calcification on chest radiograph and malignancy on computed tomography (CT) are incorrect in a substantial portion of cases (SOR: B, based on limited-quality diagnostic cohort studies), spiral CT with contrast is still diagnostically useful in making decisions regarding watchful waiting, needle biopsy, or surgery (SOR: B, based on a decision analysis study).

18-fluorodeoxyglucose positron emission tomography (FDG PET) is useful for assessing malignancy risk (SOR: B, based on decision analysis study), but not for solitary pulmonary nodules <1 cm (SOR: C, based on expert opinion).

Clinical commentary

Direct more costly, invasive tests to those with higher risk of malignancy
Parul Harsora, MD
Rhesa Sanni-Thomas, DO
UT Southwestern Medical Center, Dallas, Tex

Risk stratification of a solitary pulmonary nodule allows the clinician to direct more costly and invasive testing to patients with a higher probability of malignancy. Historical factors such as previous cancer, advanced age, and smoking increase suspicion for malignancy, but CT is generally warranted in all new solitary pulmonary nodules found on chest radiographs. It’s important to obtain a thorough history regarding symptoms (cough, night sweats, weight loss), occupational exposure (asbestos, bird droppings, decaying wood), travel, and comorbid conditions (especially immunocompromised states); this is likely to prove helpful in the workup.

FAST TRACK

A nodule unchanged for more than 2 years requires no further workup

Evidence summary

A solitary pulmonary nodule, or “coin lesion,” is an intraparenchymal finding on chest radiograph or CT that is less than 3 to 4 cm in diameter and not associated with atelectasis or adenopathy. Malignancy rates range from 15% to 75%, depending on the population studied.¹ Although early detection of malignancy portends a major improvement in survival (up to 75% at 5 years following surgical resection of stage IA disease), most lung cancers progress asymptomatically until quite advanced.²

The presumed benign nature of lesions that are either unchanged over 2 years or have central calcifications is based on 3 retrospective studies from the 1950s.^3-6 However, these should not be considered absolutes. A recent study revisiting the original data calculated the predictive value of benign nature based on no growth to be only 65% (95% confidence interval [CI], 47%–83%).⁷ Also, a study assessing the accuracy of radiologists’ assessment of calcification in solitary pulmonary nodules compared with thin-section CT found that 7% of “definitely calcified” nodules on chest radiograph lacked calcification on thin-section CT.⁸

Which clinical variables best predict malignancy?

The best available clinical decision rule was derived and validated from a single split population of patients with solitary pulmonary nodules.⁹ The outcome variable was defined as malignancy based on histologic tissue analysis or benignity by radiographic stability or resolution over 2 years. The authors did not report whether those determining outcomes and predictors were appropriately blinded.

The authors found that 3 clinical variables (age, smoking history, and cancer history) plus 3 radiographic variables (diameter, spiculation, and nodule location in the upper lobes) were independent predictors of malignancy. An online calculator using this prediction model is available at www.chestx-ray.com/SPN/ SPNProb.html.¹⁰

FAST TRACK

CT is costeffective when the probability of malignancy is less than 90%

CT or PET?

Three comparative studies observed 8 to 12 radiologists’ readings of high-resolution CT images of 28 to 56 patients with solitary pulmonary nodules (established diagnoses by either histology or stability over time).^11-13 Approximately half the nodules represented malignant lesions.

Radiologists assigned a level of confidence to their assessment of each case as benign or malignant. At a minimum, they were informed of each patient’s age and gender, and in 2 studies they also knew other information, such as the patient’s smoking and cancer histories. The study showed that the radiologists would have correctly diagnosed a pair of solitary pulmonary nodule cases, one malignant and one benign, between 75% and 83% of the time. Conversely, 17% to 25% of the time they would have diagnosed the case pair incorrectly.

Evidence-based answers from the Family Physicians Inquiries Network