PROSTATE
Prostate
:
- Glandular
organ
- Most
common histology is adenocarcinoma (typical dose to adenocarcinoma
of the prostate is 8000 cGy as opposed to the typical dose to
adenocarcinoma of 5000 cGy because disease usually occurs on the
periphery of the prostate where the tissue is more of a muscular
tissue)
- Has
2 lobes
- Location
: inferior to the base of the bladder / anterior and contiguous
with the rectum (the posterior portion of the prostate is connected
to the rectum)
- Seminal
vesicles are on each side of the prostatic lobes
- Upon
digital exam the prostate should feel like the tip of the nose
if it is normal
Morphology
of Prostate:
- Peripheral
zone – consists of 70% of the glandular prostate (this is
the site of 95% of all carcinomas of the prostate)
- Central
zone – 25% of the prostate
- Periprostatic
zone – urethral segment (benign hypertrophy occurs here)
- Fibromuscular
– anterior of the prostate
PSA
– prostatic specific antigen (an antigenic enzyme
released by the prostate and found in abnormally high concentrations
in the blood of men with prostate cancer.)
- Should
start getting PSA read at 50 years old
- Digital
exams should be started at 40 – 45 years old
- 50%
of digitally found lumps are cancerous
Benign
Hypertrophy – benign enlargment of the prostate
- as
the male ages the prostate will naturally get larger and their
PSA level will rise
-
this natural enlargement and elevation of the PSA can be mistaken
for cancer
- biopsy
is the only way to know for sure that cancer is present (definitive
diagnosis)
- Ultrasound
Directed Transrectal Needle Biopsy is performed on many spots
in the prostate
- Bening
hypertrophy must be ruled out
TURP
– Transrectal Urethral Resection of the Prostate
Adriomyacin
(doxorubicin) – cardiac sensitizer
Bleomyacin
– lung sensitizer (given to patients with sarcomas because
they metastasize to the lungs and a lower dose can be given)
Peripheral
Neuropathy – nerve endings are numbed, due to taking chemo
agents
Prostate
Staging:
Stage
1 : minimal disease that is not detectable on digital exam
Stage
2 : larger tumors that are confined to the prostate
Stage
3 : extracapsular invasion and spread to the seminal vesicles
Stage
4 : invasion of the bladder, rectum or pelvic wall fixation.
Also anything with Nodes positive
Nodes
:
Prostate
cancer will first invade the seminal vesicles before spread to the
nodes
High
Risk Nodes are :
- Periprostatic
nodes
- Obturator
nodes
Other
Nodes Involved:
- External
and Common Iliacs
- Other
Pelvic Nodes
- Paraaortic
nodes
Distant
Spread : same as breast it goes to BONE
Patient
History :
- Chances
of developing Prostate Cancer increase with age
- Prostate
cancer is very slow growing disease
- If
it occurs in young men it will be aggressive like breast cancer
is in young woman
- If
patient presents with Nodes Positive then treatment will be different
than a patient with no positive nodes (4 Field Box would be used
for positive nodes to include the Nodes)
Treatment
Options:
Nodes
Positive : 4 Field Box (15 x 15)
AP/PA
Borders: same as endometrial
- Anterior
: L5
- Posterior
: obturator foremen (does not spread down / spreads up with the
flow of lymph)
- Lateral
Borders : 1 – 1 1ž2 cm beyond the pelvic rim, brim, whatever
u wanna call it ;)
Lateral
Fields:
- Anterior
: 1cm post on the pubic symphasis
- Posterior
: 1ž2 of the anterior portion of the rectum (because the prostate
is contiguous with the rectum posteriorly) including S2 –
S3
- Superior
L5
- Inferior
: obturator foreamen
Blocks
are used : to block the bowel (only for 4 Field BOX!!!! Small Bowel
will not be in the field unless the nodes are postive and these
large fields are used)
Organs
at Risk : small bowel (40 Gy), bladder and rectum (50 Gy)
If
prostate needs a high dose (over tolerance of the bowel, bladder
and rectum) then a Cone Down is done at the appropriate dose to
note overdose these organs
Arc
Therapy : another option that is sometimes implemented
(most commonly seen on 360 degree Esophogeal Fields)
- Arc
treatments must be QA'd on the day of treatment
- Mu's
are measured in mu/degree
- Integral
Dose increased with Arc Therapy because all of the tissue receives
some dose even though it will be less to each part in the rotation
Conformal
Therapy of the Prostate:
- Only
used if there is no nodal involvment
- Less
overall involvment
- Only
sometimes used if there is involvment of the seminal vesicles
- Often
when conformal therapy is used the patient must be placed on Hormones
before the treatment to shrink the tumor to an acceptable size
- Anti-testoterone
and Androgens : DES (diethylstilbestrol), Lupron, Levicour are
given
- Or
surgery is done (removal of the testis, interstitial and leydig
cells produce testosterone)
- Both
Hormones and Surgery do the same thing and leave the patient impotent
- Androgen
is a male hormone like testosterone
Hormones
will cause patient to develop :
- gyecomastia
(male breasts / often treated before conformal treatment with
a 6cm circle)
- feminization
of patient
- depression
After
Hormone therapy then Conformal Therapy is done
Conformal
: MLC's Are used to conform to the prostate and only some
of the surrounding tissue
with
conformal therapy or IMRT only the bladder and rectum are at risk
(not the small bowel)
IMRT
treatment of the Prostate : Intensity Modulated by the
MLC leaves so Prostate receives tumorcidal dose and the surrounding
healthy tissue can a 20% lower dose.
- IMRT greatly
reduces impotency as with the other treatments the risk of impotency
is higher
- Also side effects
are reduced
Side
Effects :
Diarrhea
– lomitil and immodium
Naseau
– compazine
Pain
in urethra - pyrimidine
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