Oncology: Prostate & Colorectal Cancer Flashcards
What do almost all prostate cancers rely on to grow?
Androgens (e.g. testosterone)
What are the majority of prostate cancers?
Adenocarcinomas (95)
Where do the majority of prostate cancers grow?
In the peripheral zone of the prostate
Risk factors for prostate cancer?
- Increasing age
- Family history
- Black African or Caribbean origin
- Tall stature
- Anabolic steroids
- Gene mutations (BRCA II and pTEN)
Location of prostate carcinoma vs benign prostatic hyperplasia?
Prostate adenocarcinoma –> glandular tissue in posterior or peripheral zone
BPH –> centre of gland
Presentation of prostate cancer?
- May be asymptomatic (e.g. diagnosed by routine rectal exam)
- Lower urinary tract symptoms (LUTS) e.g. poor stream, hesitancy, nocturia, dribbling and increased frequency
- Haematuria
- Impotence
- 1 in 5 present with metastatic prostate cancer e.g. anaemia, bone pain, pathological fracture, spinal cord compression, weight loss
Typical rectal examination findings in prostate cancer?
Enlarged, hard, craggy gland (or nodule) –> obliteration of the median sulcus
1st line investigation in suspected prostate cancer?
PR exam
Describe a benign prostate
Smooth, symmetrical, slightly soft, maintained central sulcus (dip in between right and left lobe)
Describe a prostate in protastatic hyperplasia
generalised enlargement
Describe a prostate in protastatis
enlarged, tender, and warm
Describe a cancerous prostate
Firm or hard, craggy, or irregular, with loss of central sulcus, may be a hard nodule –> 2 week wait urgent cancer referral to urology
Bedside investigations in suspected prostate cancer?
1) PR exam
2) Urine dip
What blood test can be done in suspected prostate cancer?
PSA (prostate specific antigen) –> counselling prior due to poor sensitivity and specificity
1st line imaging in prostate cancer?
Mutliparametric MRI
What is PSA produced by?
The epithelial cells of the prostate produce prostate-specific antigen (PSA).
It is specific to the prostate, meaning it is not produced anywhere else in the body.
What is PSA?
PSA is a glycoprotein that is secreted in the semen, with a small amount entering the blood.
Purpose of PSA?
Its enzymatic activity helps thin the thick semen into a liquid consistency after ejaculation
How is PSA testing used in prostate cancer?
A raised level can be an indicator of prostate cancer.
PSA testing may lead to the early detection of prostate cancer, potentially leading to effective treatment and preventing significant problems.
However, research has failed to show that the benefits of using PSA for screening outweigh the risks.
In the UK, when can men request a PSA?
Aged 50 and over
Why is PSA testing unreliable?
PSA testing has a high rate of false positives (75%) and false negatives (15%).
Common causes of a raised PSA?
- Prostate cancer
- Benign prostatic hyperplasia
- Prostatitis
- Urinary tract infections
- Vigorous exercise (notably cycling)
- Recent ejaculation or prostate stimulation
Dangers of false positives in PSA testing?
- Further investigations (including invasive prostate biopsies) which may have complications
- May lead to the unnecessary diagnosis and treatment of prostate cancer that would never have caused problems
Dangers of false negative in PSA testing?
False negatives may lead to false reassurance.
How are the results of an MRI in prostate cancer reported?
On a Likert scale:
1 – very low suspicion
2 – low suspicion
3 – equivocal
4 – probable cancer
5 – definite cancer
What does 4 on the Likert scale indicate?
Probable cancer
Prostate biopsy is the next step in establishing a diagnosis in suspected prostate cancer.
The decision to perform a biopsy depends on what?
1) MRI findings (Likert 3 or above)
2) Clinical suspicion (exam and PSA level)
What Likert score would indicate the need for a prostate biopsy?
3 or above
What are the 2 options for prostate biopsy?
1) Transrectal ultrasound-guided biopsy (TRUS)
2) Transperineal biopsy
What does a TRUS involve?
Involves an ultrasound probe inserted into the rectum, providing a good indicate of the size and shape of the prostate.
Guided biopsies are taken through the wall of the rectum, into the prostate.
What does a transperineal biopsy involve?
Transperineal biopsy involves needles inserted through the perineum. It is usually under local anaesthetic.
What are the main risks of a prostate biopsy?
1) Pain (particularly lower abdominal, rectal or perineal pain)
2) Bleeding (blood in the stools, urine or semen)
3) Infection
4) Urinary retention due to short term swelling of the prostate
5) Erectile dysfunction (rare)
What can be used to look for bony mets in prostate cancer?
Isotope bone scan (also called a radionuclide scan or bone scintigraphy)
What happens in an isotope bone scan?
1) A radioactive isotope is given by intravenous injection
2) A short wait (2-3 hours) to allow the bones to take up the isotope
3) A gamma camera is used to take pictures of the entire skeleton.
How do bony mets appear onn an isotope bone scan?
Metastatic bone lesions take up more of the isotope, making them stand out on the scan.
What garding system is used in prostate cancer?
Gleason Grading System
This is specific to prostate cancer.
What is the Gleason Grading System based on?
The Gleason grading system is based on the histology from the prostate biopsies.
What does a greater gleason score indicate?
The greater the Gleason score, the more poorly differentiated the tumour is (the cells have mutated further from normal prostate tissue) and the worse the prognosis is.
The Gleason score will be made up of two numbers added together for the total score (e.g. 3 + 4 = 7).
What are these 2 numbers?
1) The first number is the grade of the MOST PREVALENT PATTERN in the biopsy
2) The second number is the grade of the second most prevalent pattern in the biopsy
What Gleason score is considered low risk for prostate cancer?
6 is considered low risk
What Gleason score is considered intermediate risk for prostate cancer?
7 (3 + 4 is lower risk than 4 + 3)
What Gleason score is considered high risk for prostate cancer?
8 or above
What staging system is used for prostate cancer?
TNM staging system
Describe the ‘T’ aspect in the TNM staging system (TX to T4)
TX – unable to assess size
T0 - no evidence of 1ary tumour
T1 – too small to be felt on examination or seen on scans
T2 – contained within the prostate
T3 – extends out of the prostate
T3a - extracapsular extension (unilateral or bilateral)
T3b - tumour invades seminal vesicle(s)
T4 – spread to nearby organs