Chest
Volume 143, Issue 2, February 2013, Pages 436-443
Journal home page for Chest

Original Research
Lung Cancer
Characteristics of Subsolid Pulmonary Nodules Showing Growth During Follow-up With CT Scanning

https://doi.org/10.1378/chest.11-3306Get rights and content

Objective

The positive results of a screening CT scan trial are likely to lead to an increase in the use of CT scanning, and, consequently, an increase in the detection of subsolid nodules. Noninvasive methods including follow-up with CT scanning, to determine which nodules require invasive diagnosis and surgical treatment, should be defined promptly.

Methods

Between 2000 and 2008, from our database of > 60,000 examinations with CT scanning, we identified 174 subsolid nodules, which showed a ground-glass opacity area > 20% of the nodule and measured ≤ 2 cm in diameter, in 171 patients. We investigated the clinical characteristics and CT images of the subsolid nodules in relation to changes identified during the follow-up period.

Results

The nodule sizes ranged from 4 mm to 20 mm at the first presentation. Nonsolid nodules numbered 98. During the follow-up period, 18 nodules showed resolution or shrinkage, and 41 showed growth of 2 mm or more in diameter. The time to 2-mm nodule-growth curves calculated by Kaplan-Meier methods indicated that the 2-year and 5-year cumulative percentages of growing nodules were 13% and 23% in patients with nonsolid nodules and 38% and 55% in patients with part-solid nodules, respectively. Multivariate analysis disclosed that a large nodule size (> 10 mm) and history of lung cancer were significant predictive factors of growth in nonsolid nodules.

Conclusions

An effective schedule for follow-up with CT scanning for subsolid nodules should be developed according to the type of subsolid nodule, initial nodule size, and history of lung cancer.

Section snippets

CT Scan Selection and Review

From > 60,000 CT scan examinations carried out at the Tochigi Cancer Center between January 2000 and June 2008, we extracted 1,065 cases for which descriptive terms referring to GGO were used in the reports. We reviewed all images from the cases and selected target cases according to the following criteria: subsolid nodules ≤ 2.0 cm in diameter, performance of at least one high-resolution CT (HRCT) scan and a follow-up CT scan, and a proportion of GGO > 20%. We used these criteria because we

Results

Regarding type of subsolid nodule, nonsolid nodule cases numbered 98 and part-solid nodule cases numbered 76. Patients' characteristics according to the type of subsolid nodule are shown in Table 1. Pathologic examination revealed that three patients were diagnosed with atypical adenomatous hyperplasia (AAH), 36 had AIS, 11 had MIA, and six had invasive adenocarcinoma according to the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society

Discussion

In this study, some patients underwent resection at different points of growth, and because of their older age and comorbidity, others continued to be followed up in spite of growth. In this situation, we selected the Kaplan-Meier method to calculate the percentage of subsolid nodules showing growth because this method can be implemented to deal with censored cases. In the analysis with the Kaplan-Meier method, we set ≥ 2 mm growth as an event for the following reasons: a 2 mm size change is a

Acknowledgments

Author contributions: Dr Matsuguma had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Matsuguma: contributed to study design, data acquisition, and manuscript preparation.

Dr Mori: contributed to manuscript preparation and read and approved the final manuscript.

Dr Nakahara: contributed to manuscript preparation and read and approved the final manuscript.

Dr Suzuki: contributed to manuscript preparation and

References (23)

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Funding/Support: This work was supported in part by a Grant-in-Aid for Cancer Research from the Ministry of Health, Labour and Welfare of Japan, and by the second-term comprehensive 10-year strategy for cancer control.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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