Characteristic of Lung Cancer From Secondary Lung Nodule in Patient With Preexisting Indeterminate Solitary Pulmonary Nodule

Abstract

SESSION TITLE: Lung Cancer SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, November 1, 2017 at 01:30 PM - 02:30 PM PURPOSE: New lung nodules detected during CT screening for lung cancer have shown to be at higher risk of lung cancer than incidentally detected at baseline screening. As these nodule develop within short time from the previous CT scans one year back, they are also considered to be more aggressive growth behavior. However, as of now, there is no information of the characteristics of lung cancer from secondary nodules detected in patient with preexisting indeterminate solitary pulmonary nodules. We describe our experience with these similar patients enrolled in lung nodule surveillance program METHODS: Patients with incidentally detected lung nodule ( Primary nodule) without any major medical problem requiring pulmonary specialist follow up were enrolled in lung nodule surveillance program and followed with repeat CT scan as per American college of chest physicians guidelines. Retrospective analysis of all patients enrolled in lung nodule surveillance program was done and patient with secondary nodule were analyzed. Also, all lung cancer from both primary and secondary nodules were compared. From January 2009 to June 2016, 866 patients with primary nodule enrolled were enrolled in the program. 108 (12%) developed secondary nodule during the surveillance period, Out of which, eight patients (7% of secondary nodule) were ultimately diagnosed with lung cancer(Table1). Four patients had Nonsmall lung cancer, two had poorly differentiated cancer and one patient had limited small cell cancer. Out of the 7 primary lung cancer, Five (71%) were diagnosed as early stage lung cancer and underwent curative treatment with either resection or radiation. RESULTS: The risk of lung cancer from the primary nodule was 1.06%( 8 patients) and 71% of these cases were diagnosed in early stage, and 57% were adenocarcinoma. No small cell or poorly differentiated caner was noted. There was significant difference between the probability of lung cancer predicted by from Mayo clinic , Veteran affairs and Brockufull model formula. In general, Mayo clinic model had the highest probability of lung cancer and Brocku model has the least probability of risk of lung cancer. Nine (56%) patients with lung cancer had probability of lung cancer more than 65% based on Mayo clinic model, compared to only one patients ( 6%) based on VA and Brocku model. There was no difference in the predictive probability of lung cancer from primary and secondary nodule( graph1). CONCLUSIONS: The incidence of secondary nodule detected during lung nodule surveillance program is 12% , and is higher than reported in lung cancer screening trials rate of 3 to 7%. Also, incidence of cancer in these secondary nodule is 8%, higher than risk of cancer from primary nodule( <5%) and higher than reported in lung cancer screening trials( 4%). Even though the lung cancer from secondary nodules were rapidly growing and more aggressive, most cases (70%) were detected in early stage. CLINICAL IMPLICATIONS: Newly detected secondary solitary pulmonary nodule in patient with existing nodule are at higher risk of lung cancer than incidental nodule. All the available predictive model underestimate the probability of lung cancer in these nodules. Patients with secondary nodules should be followed more carefully. DISCLOSURE: The following authors have nothing to disclose: Mohan Rudrappa, Laxmi Kokatnur No Product/Research Disclosure Information