5-year lung cancer screening experience: growth curves of 18 lung cancers compared to histologic type, CT attenuation, stage, survival, and size.
BACKGROUND
Although no study has prospectively documented the rate at which lung cancers grow, many have assumed exponential growth. The purpose of this study was to document the growth of lung cancers detected in high-risk participants receiving annual screening chest CT scans.


METHODS
Eighteen lung cancers were evaluated by at least four serial CT scans (4 men, 14 women; age range, 53 to 79 years; mean age, 66 years). CT scans were retrospectively reviewed for appearance, size, and volume (volume [v] = pi/6[ab(2)]). Growth curves (x = time [in days]; y = volume [cubic millimeters]) were plotted and subcategorized by histology, CT scan attenuation, stage, survival, and initial size.


RESULTS
Inclusion criteria favored smaller, less aggressive cancers. Growth curves varied, even when subcategorized by histology, CT scan attenuation, stage, survival, or initial size. Cancers associated with higher stages, mortality, or recurrence showed fairly steady growth or accelerated growth compared with earlier growth, although these growth patterns also were seen in lesser-stage lung cancers. Most lung cancers enlarged at fairly steady increments, but several demonstrated fairly flat growth curves, and others demonstrated periods of accelerated growth.


CONCLUSIONS
This study is the first to plot individual lung cancer growth curves. Although parameters favored smaller, less aggressive cancers in women, it showed that lung cancers are not limited to exponential growth. Tumor size at one point or growth between two points did not appear to predict future growth. Studies and equations assuming exponential growth may potentially misrepresent an indeterminate nodule or the aggressiveness of a lung cancer.
Lindell
Rebecca M
RM
Department of Radiology, Mayo Clinic, Rochester, MN. Electronic address: lindell.rebecca@mayo.edu.
Hartman
Thomas E
TE
Department of Radiology, Mayo Clinic, Rochester, MN.
Swensen
Stephen J
SJ
Department of Radiology, Mayo Clinic, Rochester, MN.
Jett
James R
JR
Department of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
Midthun
David E
DE
Department of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
Mandrekar
Jayawant N
JN
Department of Biostatistics, Mayo Clinic, Rochester, MN.
D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology*; D002282:Adenocarcinoma, Bronchiolo-Alveolar / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology*; D049109:Cell Proliferation; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden