NCCN Guidelines for Patients
: Lung Cancer Screening
Screening with LDCT is used to find nodules in the
lungs. Nodules are small, round masses of tissue. Many
people have nodules. Nodules can be caused by cancer,
infections, scar tissue, or other conditions. Most nodules
are benign—not cancer.
Nodules caused by cancer have specific traits. First, they
aren’t likely to have calcium buildup. Second, they often
have rough edges and odd shapes. Third, they often
grow faster and are larger in size than nodules without
cancer. Nodules are measured in mm (
” is about 1 mm long.
Doctors also assess the density of a nodule to tell if it
may be cancer. Density refers to how well the x-rays
from the LDCT go through the lung. Think of a flashlight
shining in the dark. If the light doesn’t hit an object, it is
dark a few feet away from the flashlight. If the light does
hit an object, the object reflects the light and can be seen.
Nodules are divided into three groups based on density:
• Solid nodules have high density. They look evenly
white on an LDCT scan.
• Non-solid nodules have low density. They look
like hazy clouds on an LDCT scan. Your doctors
may call this type of nodule a “pure ground-glass
opacity” or a “pure ground-glass nodule.”
• Part-solid nodules have both high and low areas of
density. These nodules have both solid white and
hazy parts. Your doctors may call this type of nodule
a “mixed ground-glass nodule,” “semi-solid nodule,”
or “subsolid nodule.”
Part 4 describes the recommended screening process
after the first LDCT. Often, the use of one LDCT detects a
nodule but isn’t clear whether the nodule is lung cancer.
Thus, the first LDCT—the baseline test—is compared to
follow-up LDCTs. Your doctors will look for increases in
size or density. Such changes are likely signs of cancer.
If no lung nodules are found, your next LDCT should be
in 1 year. Screening with LDCT should occur every year
for at least 2 years. After 2 years, your doctors may want
you to continue yearly screening. However, screening
isn’t recommended for people with poor health, who
if diagnosed with cancer would not be able to receive
Part 4: The screening process