One in four intermediate-sized (8-20 mm) pulmonary nodules were found to be malignant, based on results from a retrospective study of 377 patients seen in 18 community pulmonology practices.
Malignant nodules were more likely to be found in current or former smokers and to be larger than the benign nodules.
Further, despite guideline recommendations for surveillance of pulmonary nodules with less than a 5% pretest probability of malignancy, 44% of 36 patients with low-risk pulmonary nodules underwent at least one invasive procedure.
“To our knowledge, this is the first study that documents the prevalence of cancer (25%) in patients with intermediate-sized nodules referred to community-based pulmonologists,” wrote Dr. Nichole T. Tanner of the Medical University of South Carolina, Charleston, and her coauthors in the study published online (Chest 2015 June 18 [doi:10.1378/chest.15-0630]). “This finding has implications for managing pulmonary nodules in the community; because the risk of cancer is substantial, patients should be managed based on their individualized risk for malignancy.”
Biopsy – either by transthoracic needle aspiration or bronchoscopy – was performed in 33% (125) of patients, of whom 35% were found to have a malignancy and 57% had a specific benign diagnosis; biopsies in 8% were nondiagnostic and those patients were followed for 2 years.
Referrals for surgery were given to 20% (77) of patients; 19 had previously undergone a biopsy, with 11 having a nondiagnostic biopsy and eight having a received a benign result. Of patients who underwent surgery, 65% were diagnosed with a malignancy, and 35% had benign disease. However, the rate of surgical resection was similar regardless of patients’ pretest probability of malignancy.
PET scanning, performed in 37% of patients, was more likely in those who had a biopsy or surgery. The overall accuracy of PET was 74%, and the false-negative rate decreased slightly as the size of the nodule increased.
“Guidelines recommend surgery if the pretest probability of cancer is high (pCA > 65%) because a negative biopsy would not dissuade the clinician from pursuing a definitive diagnosis and a positive biopsy would lead to surgery anyway.”
The researchers pointed out that there are a range of noninvasive options now available to determine the likelihood that a nodule is malignant, such as CT scanning with the use of volumetric software to measure diameter and volume-doubling time of a nodule in between scans.
The study was supported by Integrated Diagnostics. All but one study author declared consulting fees, grant funding, stock options, or employment with Integrated Diagnostics.