NCCN Guidelines for Patients® | Prostate Cancer - page 10

10
NCCN Guidelines for Patients
®
: Prostate Cancer
Version 1.2014
Part 2: Cancer staging
2.1 Prostate-specific antigen
PSA (
p
rostate-
s
pecific
a
ntigen) is a protein made by
the fluid-making cells that line the small glands inside
the prostate. These cells are where most prostate
cancers start. PSA turns semen that has clotted after
ejaculation back into a liquid. However, PSA levels can
be measured from a blood sample since some of it enters
the bloodstream. PSA levels are used for cancer staging,
treatment planning, and checking treatment results. PSA
levels discussed in this booklet include:
PSA level
is the number of nanograms of PSA per
milliliter (ng/mL) of blood.
PSA density
is the PSA level in comparison to the
size of the prostate. It is calculated by dividing the
PSA level by the size of the prostate. The size of
the prostate is measured with a TRUS (
t
rans
r
ectal
u
ltra
s
ound).
PSA velocity
is how much PSA levels change within
a period of time.
PSA doubling time
is the time it takes for the PSA
level to double.
The larger the prostate, the more PSA it can make.
Large prostates can be a result of cancer or other health
problems of the prostate. Some medications can also
affect the PSA level. PSA increases after ejaculations and
vigorous exercise, especially running or bicycling. Thus,
refrain from sex or exercise for 3 days before a PSA test.
You will then have a more accurate PSA test.
2.2 Digital rectal exam
Doctors use a DRE (
d
igital
r
ectal
e
xam) to screen for
cancer, rate the cancer stage, and assess treatment
results. For this exam, your doctor will put a glove on his
or her hand and then put lubricant on his or her index
finger. Next, your doctor will insert a finger into your
rectum to feel your prostate as shown in Figure 2. Your
prostate can be felt since it is on the other side of the
rectal wall. Bear in mind that not all aspects of the cancer
can be felt on this exam.
Figure 2. DRE
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