About prostate cancer

Knowledge Empowers

"Ye shall know the truth, and the truth shall make you free." The shock of being diagnosed with prostate cancer may be overbearing. The best way to overcome the stress of this disease is to be educated. Finding a problem presents an opportunity in life. It takes awareness, assessment and attitude to successfully overcome the problem. We want to make sure that each patient has a full understanding of how prostate cancer is diagnosed and the implications of the diagnosis. Prostate cancer treatment should be uniquely individuallized, and that is what we strive to do. We strive to make every patient aware of their diagnosis, of how it will affect their lives. We make an accurate assessment of their risks and we help them change their attitude to conquer their disease.

Epidemiology

Prostate cancer is the most common cancer in US men since 1984 and accounts for 33% of all cancers. The incidence peaked in 1992, about 5 years after the advent of the PSA test, and then dropped until 1995 when it started rising again. The risk of death from prostate cancer has been dropping in the US since 1991. African-Americans are at increased risk with a ratio of 1.6 times compared to Caucasians. Since the introduction of PSA, a serum cancer marker, cancer non detectable on physical exam (AJCC stage T1c) accounts for 75% of all newly-diagnosed cancers.

Risk and Mitigating Factors

Familial influences are clearly a factor as the risk of prostate cancer in an individual is directly related to relatives with prostate cancer under 55 years of age, the number of affected relatives and their age of onset (the younger the higher the risk).  Multiple genes have been found to be involved with the development of prostate cancer.  The factors in the environment that contribute to the risks are androgens (testosterone), Insulin-like growth factor (obesity), Vitamin D and its receptor (lack of Vitamin D contributes to an increased risk of death from prostate cancer and Japanese with high Vitamin D diets from fish have very low incidences of prostate cancer).  Vasectomy has been discredited to selection bias and likely is not related.  Sexual activity protects against prostate cancer (21 or more ejaculations per month during years 20-40s).  Dietary fat, smoking, and alcohol are contributors to the risk.  Recently, the Prostate Cancer Prevention Trial found that Finasteride (Proscar) used as a medicine to shrink the prostate and improve symptoms from BPH reduced the prevalence of prostate cancer by 28%.  A second trial using Avodart (Dutasteride) has confirmed the protection.  Antioxidants such as lycopene, vitamin E, selenium, green tea, soy have been suggested as protection against development of prostate cancer.

The PSA Tumor Marker

The PSA test represents the advent of one of the most successful serum tumor markers (blood test that detects cancer) in clinical application today.  Controversially, some are debating that it has over-diagnosed prostate cancer, leading to bothersome side effects of treatment.  However, since its application, prostate cancer has migrated (stage migration) from a disease that was detected with digital rectal exam to a non-palpable (not felt on exam) cancer that is detected earlier and more likely curable.  PSA is one of 3 kallikrein serine proteases (proteins that cuts other proteins)-specifically human kallekrein3.  It is exclusively expressed in the prostate gland, and its main function is to liquefy semen during fertilization.  PSA levels are highly dependent on testosterone and there are studies now suggesting men who have low testosterone levels (hypogonadism) usually have very low PSAs. Standard cut-offs for elevated PSA levels in the cohort of hypogonadic men (those that need testosterone) may be too high and delay diagnosis.  Men on testosterone supplementation should have there PSAs monitored closely.  Trauma, inflammation, and infections can cause increases in PSA.  Men with benign prostatic hypertrophy, or BPH, can have higher levels of PSA as there is more prostate tissue.  Any men on Finasteride (Proscar), or Dutasteride(Avodart) which are medications used to shrink the prostate will decrease the PSA to 50% in 6 months after starting the medications.  The 1 mg formulation of Finasteride (trade name Propecia) used to treat male pattern baldness also results in the same decrease. If the PSA does not decrease to 50% or rises, prostate cancer should be suspected.  As PSA has been useful, it has not been accurate enough to tell if one has prostate cancer or not- this would require a transrectal prostate biopsy.  PSA levels only gauge one’s risk for prostate cancer. 

PSA Kinetics

To improve detection of cancer and mitigate the risk of performing negative biopsies, certain values are suggested that increase the risk of cancer.  Calculations of PSA density over 0.15 ng, PSA velocity or an increase of 0.75 ng/ml in a year, prompt prostate biopsy.  PSA threshold or cut-off of 4.0 ng/ml was chosen initially because it was a cut-off to detect at least 95% prostate cancer in men between ages of 50-70.  However, most variations of PSA are due to BPH or benign hypertrophy (which increases the prostate size and PSA expression).  Younger men should have less BPH, and a cut-off of 2.5 ng/mL is suggested for men under 50 years of age.  Alternately, PSAs can increase above 4.0 ng/ml for men over age 70, and the cut-offs are generally age-dependent.  The history of the elevation is also important, and an isolated elevation of PSA should also be re-measured if no prior PSAs have been known (and the digital rectal exam was normal). 

Transrectal Ultrasound Prostate Biopsy (TRUS)

Needle core biopsy of the prostate remains the gold-standard of prostate cancer diagnosis.  Ultrasound alone cannot predict the presence of prostate cancer because  up to 39% of cancers are NOT visible on transrectal ultrasound.  The predominant extended pattern of biopsy involving 12 needle cores is optimal in the detection of prostate cancer.  There are other modes of ultrasound called Power Doppler TRUS or color amplitude imaging (CAI) that examine the blood flow to the prostate and finds neovascularity or the development of new blood vessels, i.e. feeding a tumor.  However, even with these techniques in a large studies, 45% of cancers still went undetected by ultrasound alone with any modality used to improve its imaging characteristics.  Many new techniques are under investigation and involve prostate elastography that examines tissue displacement during compression of the prostate (cancer is a hard nodule and has decreased tissue elastiticity). 

Prostate Cancer Staging

Staging of any cancer determines the treatment for that cancer.  The general rule for all cancers is curative treatment if the cancer is organ-confined.  Alternately, if the cancer has mestastasized, then chemotherapy, or in case of prostate cancer, hormonal therapy is used to slow the cancer. Prostate cancer is unique in that there is a variant of prostate cancer (the indolent variety) that can remain localized or confined to the prostate for a very long time.  Thus watchful waiting or observation in men with less than a 10 year life expectancy is suitable.  Staging of prostate cancer is mostly determined clinically, in that we as physicians deduce (based on the PSA, imaging by CT/bone scan) that either the cancer is either confined, extensive, or has metastasized.   This is generally accurate in estimating the extent of the cancer at the time of diagnosis but it is NOT at 100%.   There are cancers that we deduce as early stage and organ-confined which have micrometastases or cells that have escaped the prostate gland and cannot be detected.   When a patient decides to undergo surgery, there is a second set of pathological staging that is more accurate in analyzing the extent of the cancer in the prostate specimen removed. 

 

 

Key Points and Terms

Below are key points a patient needs to be familiar with to understand how prostate cancer is detected, and how it is staged. It is important to understand the basis of all the tests that were done prior to arriving at the prostate cancer diagnosis. We hope that the information provided can educated and empower our patients in understanding their disease process.

Should this information be not enough to allow full understanding, please come in for a consultation. Call us for a convenient appointment today!