Lung Cancer: Novel Methods for Lung Cancer Diagnosis |

The Performance of Two Commercial, Diagnostic Blood Tests to Evaluate the Incidentally Detected, Indeterminate Pulmonary Nodule FREE TO VIEW

Gary Lin, MD; Pragya Tripathi, MBBS; Harris Naemi, BA; Viswam Nair, MD
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Santa Clara Valley Medical Center, San Jose, CA

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;150(4_S):733A. doi:10.1016/j.chest.2016.08.828
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SESSION TITLE: Novel Methods for Lung Cancer Diagnosis

SESSION TYPE: Original Investigation Slide

PRESENTED ON: Tuesday, October 25, 2016 at 08:45 AM - 09:45 AM

PURPOSE: Currently, risk stratifying a lung nodule is clinically and imaging based, but several commercial blood tests are now available to facilitate management independently. In our clinical lung nodule program, we are studying the performance of two of these tests. Xpresys® uses mass spectrometry to analyze 5 plasma proteins that classifies a lung nodule as either likely benign or indeterminate and is designed to “rule-out” cancer. EarlyCDT-lung® is an ELISA assay that measures 7 auto-antibodies, which stratifies risk into low, moderate or high and is designed to “rule-in” lung cancer.

METHODS: Patients from an academic medical center deemed by a pulmonary clinician to have indeterminate risk lesions were enrolled. After clinical lab phlebotomy, plasma was recovered in a research lab and then sent to the respective corporate labs to assay. Clinical and imaging data were procured from the medical record to calculate clinical nodule risk (low <5%, moderate 5-65%, high ≥65%) using the average of VA and Mayo risk prediction models. Xpresys® (Xp) classifies a nodule as likely benign if the risk of cancer is ≤16% and the remainder as indeterminate. EarlyCDT® (CDT) classifies a nodule into low (1.2%), medium (3.5%) or high (19.5%) one-year cancer risk. Malignant diagnoses were confirmed by histopathology and benign diagnoses were determined by nodule stability, diminution, resolution, or an alternative diagnosis by histopathology or culture over 2 years of follow-up.

RESULTS: From 2014 to 2016, 31 patients were enrolled, 16 and 25 of whom were tested for Xp and CDT respectively, and 10 of whom had both tests performed. To date, 4 patients have developed cancer, 7 have not, and 20 are being followed without nodule growth (median 7 months). Mean age was 63 ± 15 years, 14 patients were male, 19 were either current/past smokers, and 5 had a prior cancer ≥5 years ago. Nodule size was 1.3 ± 0.7 cm, 5 were spiculated and 11 were in the upper lobe. Average cancer risk for the cohort according to risk models was 23% comprising 2 low, 25 indeterminate, and 4 high-risk nodules. Assuming lesions not yet identified as cancer in follow up are benign, CDT had a sensitivity (Sn) of 0% but a specificity (Sp) of 95% and Xp had a Sn of 67% and Sp of 62%. Reported CDT risk (low) was discordant with high attributed clinical risk in 1 case and moderate attributed clinical risk in 21 cases. Reported Xp risk (low) was discordant with high attributed clinical risk in 1 case and moderate attributed clinical risk in 7 cases. All four cases of cancer (3 primary lung and 1 non-lung) were reported as low risk by CDT while Xp reported only the non-lung cancer as low-risk.

CONCLUSIONS: In a small, but representative population of incidentally detected, indeterminate nodules, Xp performed slightly worse for ruling-out lung cancer, while CDT was more conservative for ruling-in lung cancer than previously reported. For patients with a history of non-lung cancer, Xpresys® may not be appropriate.

CLINICAL IMPLICATIONS: Blood tests to risk stratify incidentally detected lung nodules may be complementary to “rule-out” (Xpresys®) and “rule-in” (EarlyCDT-lung®) primary lung cancer. How they perform compared to clinical risk stratification and whether they alter management requires further study.

DISCLOSURE: The following authors have nothing to disclose: Gary Lin, Pragya Tripathi, Harris Naemi, Viswam Nair

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