Micronodules Detected on CT During the NLST: Prevalence and Relation to Positive Studies and Lung Cancer

Monday, July 08, 2019

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Becky Bunn | Director of Public Relations
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Chris Martin | VP, Public Relations
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Micronodules Detected on CT During the NLST: Prevalence and Relation to Positive Studies and Lung Cancer

(Denver—July 8, 2019) – Micronodules are very small round areas of tissue in the lungs that show up on a CT scan as a white spot or shadow and can be an early sign of lung cancer.

Oncologists have struggled with establishing clear screening guidelines for this population as there is insufficient scientific data regarding the malignant potential of micronodules and the impact on the lung screening process.

In the National Lung Screening Trial (NLST), researchers sought to determine if low-dose CT screening was effective in reducing the risk of mortality from lung cancer. The study enrolled 53,452 participants and 26,722 received a low-dose CT screening. In the NLST, all cases with a 4-mm nodule (micronodule) and no other findings of lung cancer were classified as a negative study.

Now, in the Journal of the Thoracic Oncology, researchers led by Reginald F. Munden MD, DMD, Wake Forest Baptist Health and School of Medicine, Winston-Salem, N.C., analyzed a subset of those patients with micronodules to understand if the negative classification was appropriate.This subset included 11,326 (42%) of participants who had at least one CT with a micronodule. Of these cases, 5,560 (49%) had at least one positive CT examination of which 409 (3.6%) subsequently were diagnosed with lung cancer

Munden and his team examined the 409 lung cancer cases with a micronodule recorded, and found there were 13 cases in which a micronodule developed into a lung cancer. Considering the 13 cases, they represent 1.2% of the lung cancers diagnosed in the CT arm of the NLST and 0.11% of the total micronodule cases, 0.23% of the micronodule and at least one positive CT examination cases, and 3.2% of the micronodule cases diagnosed with lung cancer.

The overall survival of the non-small cell lung cancer cases arising from a 4-mm nodule was not significantly different than the survival of the CT subset diagnosed with NSCLC.

“Micronodules are very common among lung cancer screened participants and a few are capable of developing into lung cancer; however, following micronodules by annual CT screening surveillance is appropriate and does not impact overall survival or outcome,” Munden concludes.

“This is very important to support the classification of such small nodules as a negative screen because of the added burden on patients and the healthcare system of following them closer with no added benefit,” said Munden.

“While our study was not designed to assess the current recommendations set by the American College of Radiology, which recommends that nodules less than or equal to 6 mm do not require active follow up, in part our findings support this initiative and indicate annual follow-up of small nodules can be performed safely,” Munden wrote.

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About the IASLC
The International Association for the Study of Lung Cancer (IASLC) is the only global organization dedicated solely to the study of lung cancer and other thoracic malignancies. Founded in 1974, the association's membership includes more than 6,500 lung cancer specialists across all disciplines in over 100 countries, forming a global network working together to conquer lung and thoracic cancers worldwide. The association also publishes the Journal of Thoracic Oncology, the primary educational and informational publication for topics relevant to the prevention, detection, diagnosis and treatment of all thoracic malignancies. Visit www.iaslc.org for more information.

About the JTO

Journal of Thoracic Oncology (JTO), the official journal of the International Association for the Study of Lung Cancer, is the primary educational and informational publication for topics relevant to the prevention, detection, diagnosis, and treatment of all thoracic malignancies. JTO emphasizes a multidisciplinary approach and includes original research reviews and opinion pieces. The audience includes epidemiologists, medical oncologists, radiation oncologists, thoracic surgeons, pulmonologists, radiologists, pathologists, nuclear medicine physicians, and research scientists with a special interest in thoracic oncology. 


About the Author

Chris Martin, Vice President, Public Relations