Table of Contents
Screening for Prostate Cancer
Prostate cancer at the early stages does not usually show symptoms, and therefore, most of the prostate cancers are first found during screening tests. At a later stage, symptoms include having difficulty in starting urination, urinating frequently, having a weak or an interrupted flow of urine, as well as having traces of blood in the urine and semen. Two types of tests are used for screening purposes:
- Digital rectal exam (DRE).
- Prostate-specific antigen (PSA) blood test.
Digital rectal exam (DRE)
While performing a DRE, a lubricated, gloved finger is inserted into the rectum to check for any hard areas or bumps. Prostate cancer usually begins to develop in the posterior part of the prostate, and as the rectum is just behind the prostate gland, the digital examination can prove to be a useful way of detecting prostate cancers at an early stage.
Findings that suggest malignancy on digital rectal examination include:
- Prostate enlargement. If you can’t get above the gland then the size is most likely >70 g.
- Gland asymmetry.
- Median sulcus obliteration and cannot be felt.
- Fixity of prostate mucosa and the overlying rectal mucosa.
- Woody hard prostate.
- Tenderness on examination.
- Blood on the examining finger.
It is important to note that:
- The digital rectal exam is less effective than prostate-specific antigen testing.
- Since only the peripheral zone is accessible to digital rectal examination, tumors confined to the central or transitional zones may be missed, although the peripheral zone is the most common site.
- The examination might be painful if the individual has hemorrhoids; otherwise, it is a painless procedure which takes only a minute or two.
Prostate-specific Antigen (PSA)
PSA is an antigen formed by the normal and cancerous cells of the prostate gland. Mostly found in semen, PSA is present only in small amounts in the blood; thus, its detection in the blood may indicate excessive production.
Interpretation of PSA levels in the blood:
Less than 4 ng/mL for men without prostate cancer.
Possible prostate cancer:
PSA levels of more than 10 ng/mL increase the chances of having prostate cancer by more than 50%; thus, it is considered as an arbitrary cut-off point for aggressive workup and follow-up.
The higher the PSA levels, the higher the risk of having prostatic cancer as shown:
- 0-4ng/L has a 5% risk.
- 4-10ng/L have a 20% risk.
- 10-20 ng/L have a 50-60% risk.
- >20 ng/L has a 70% risk.
In the grey zone of 4-10ng/L, then do the following to help differentiate cases as high risk or low risk:
Ratio of free to total PSA level
Obtained by dividing the Free PSA by the Total PSA. If it is >15%, then the likely diagnosis is BPE, while if the ratio is <15%, then prostatic cancer is more likely since the carcinoma has less free PSA than BPE; thus, less ratio as PSA is bound to alpha-1-chymotrypsin and alpha-2-macroglobulin.
Serial measurements are done to determine the rate at which the PSA level rises per year. A rise by 0.67 ng/L or greater per year indicates malignancy is likely.
This is obtained by dividing the PSA level by the volume of the prostate. Even with the availability of several options, problems still arise from false positivity and negativity as with any other screening tests.
PSA levels are falsely elevated in the following situations (False positives):
- In prostatitis.
- After digital rectal examination.
- After sexual intercourse.
Almost 15% of men with PSA levels lower than 4 ng/mL are still diagnosed with prostate cancer on biopsy (False negatives).
Recommendations for Screening
It is important that gaps in knowledge of what could potentially lead to inappropriate PSA testing are sealed. There are more upcoming methods that can greatly improve PSA, but a lot needs to be done on them including magnetic resonance imaging and clinical decision rules. Currently, the risk: benefit ratio for PSA screening is worrying, especially given the categorization of ages to undertake it.
Randomized Trials of prostate cancer screening
Prostate, Lung, Colorectal, and Ovarian (PLCO) Screening Trial results showed that 76,693 men between 65 – 74 years in the U.S had prostate cancer. No difference in prostate cancer mortality in the screening group and the control groups was found. More cancer cases were detected in the screening group. There was 52% contamination of the control group, with prostate-specific antigen testing.
It is important to note that despite these recommendations, patients will always have their preferences and values; thus, it is important that they have access to the right information to make informed decisions. The cost for these testing and screening will also play a role in the decision that a person arrives at
European randomized study of screening for prostate cancer:
160,000 men between 55 and 69 years had prostate cancer. Statistically, a significant reduction in prostate cancer mortality with screening is possible.
Efficacy: 1.28 deaths reduced per 1000 men. 27 cancers would have to be treated to prevent another death.
More than 90% of the diagnosed prostate cancer patients undergo curative treatment. The following are the curative treatments:
Prostatectomy involves removing part or the entire prostate gland. Radical prostatectomy involves removing the entire prostate gland, as well as all the surrounding lymph nodes, from a man who has prostate cancer.
It is either done by:
- Open surgery which involves an incision at the lower abdomen.
- Laparoscopic surgery where special tools are inserted into the lower abdomen through small incisions and the tools remove the prostate.
A radical prostatectomy is an effective treatment option, but it results in urinary incontinence in up to 12% of the cases and erectile dysfunction in about 50% of the cases. It raises chances of bleeding, injury to the rectum and formation of cysts
It is the application of high energy X-rays and other particles to kill cancerous cells.
Two types of radiation therapies are used for prostate cancer:
- External beam radiotherapy (EBRT): A machine without the body is used in radiation. It is the most expensive treatment compared to any other option.
- Brachytherapy (seed implantation / interstitial radiation therapy): Radioactive seeds are implanted into the prostate to offer radiation near the prostate and thus minimize the adverse effects of radiotherapy to other organs.
Radiation therapy results in erectile dysfunction in about 50% of the cases. There are also rare incidences of chronic loose stool and urethral strictures. It is also more expensive compared to prostatectomy and has more long-term side effects.
Men can generally prevent prostate cancer by leading healthy lifestyles. This includes increasing vegetables and fruits consumption and reducing the amount of fat in one’s diet. Maintaining appropriate body weight and avoiding smoking is also a preventative measure for prostate cancer.