Our knowledge of cancer is always changing. Researchers and healthcare professionals take the knowledge gained from research studies and use it to develop practices that will help prevent, detect and treat prostate cancer, as well as improve the quality of life of men with prostate cancer.
The following information is a selection of research showing promise for prostate cancer.
Risk reduction
Risk reduction strategies may reduce the chance of developing cancer.
Noteworthy research includes:
- Researchers continue to look at the effect that diet may have on prostate cancer.
- How much meat a person eats and the way meat is cooked may increase the risk for prostate cancer. Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are known carcinogens produced when red meat is cooked at high temperatures, such as grilling and barbecuing (Nutrition and Cancer, PMID* 21526454).
- Various studies suggest that the following may be associated with a lower risk of prostate cancer (The Journal of Urology, PMID 19914662; Clinical Cancer Research, PMID 19318492; Nutrition Research [New York, N.Y.], PMID 21310299; Oncology Reports, PMID 21637922; Cancer Science, PMID 21988617; International Journal of Cancer, PMID 21823116):
- long-chain n-3 fatty acids mainly found in seafood
- glucosinolates found in cruciferous vegetables (especially broccoli and cauliflower)
- isoflavones found in soybeans
- A large randomized controlled trial (RCT), called SELECT, tested the effect of taking vitamin E and selenium supplements on the risk of prostate cancer. In previous observational studies, researchers showed that these supplements decrease the risk of prostate cancer. This was not confirmed in SELECT, and there was a statistically significant trend toward an increased risk of prostate cancer with increased vitamin E intake. The trial was stopped early when researchers found that these supplements were not reducing cancer risk and could cause harm (JAMA: The Journal of the American Medical Association, PMID 21990298).
- The Prostate Cancer Prevention Trial (PCPT) looked at finasteride (Proscar) to see if it might reduce the risk of prostate cancer. This study showed that the risk of being diagnosed with prostate cancer was 25% lower in men who took finasteride compared to those who took a placebo. However, there was a greater chance of being diagnosed with a higher risk prostate cancer. It is believed that this increased risk is related to better detection of high-risk cancers in men taking finasteride. These results make researchers hesitant to recommend finasteride for the prevention of prostate cancer (The New England Journal of Medicine, PMID 12824459; Urology, PMID 20035983; Expert Opinion on Drug Metabolism & Toxicology, PMID 20536414).
- The REDUCE trial tested dutasteride (Avodart), a drug similar to finasteride, to see if men who take it have a lower risk of developing prostate cancer. Results showed that dutasteride reduced the overall risk of prostate cancer. However, a review according to the most current prostate pathology guidelines showed that there was a greater chance of being diagnosed with a higher risk prostate cancer (The New England Journal of Medicine, PMID 21675880, PMID 20357281).
- Some studies found that taking statins (drugs used to lower cholesterol) was associated with a lower risk of prostate cancer (The Journal of Urology, PMID 21571344; Expert Opinion on Drug Safety, PMID 20377474). Another study reported that statins may play a protective role in preventing the development of advanced prostate cancer (The Prostate, PMID 20717902).
Early detection
Researchers are working to improve early detection and screening techniques for prostate cancer so that it can be found early, before signs and symptoms are noticed.
Noteworthy research includes:
- The European Randomized Study of Screening for Prostate Cancer (ERSPC) examined the effectiveness of screening for prostate cancer using prostate-specific antigen (PSA) test aloneor in combinationwith digital rectal examination (DRE). The ERSPC trial is a large trial with long follow-up. It showed that PSA screening reduced prostate cancer deaths by 20% (ArchivosEspañoles de Urología, PMID 21705812). However, the number of deaths overall was very small and the number of men who would need to be screened and treated to save one life was extremely high. More results and further analysis from these trials are expected in the future (World Journal of Urology, PMID 22116599; The New England Journal of Medicine, PMID 22417251).
- The US Preventive Task Force reviewed evidence for PSA screening to detect prostate cancer. Their review suggested that PSA screening prevented no deaths, or only a small number of deaths, from prostate cancer. As a result, the US Preventive Task Force does not recommend PSA screening to detect prostate cancer. They stated that PSA screening may do more harm than good as it results in more tests, treatment and side effects for prostate cancer (Annals of Internal Medicine, PMID 21984740).
- Researchers have shown that the prostate cancer antigen 3 (PCA3) test is a more specific test than serum PSA for early detection of prostate cancer. Prostate cancer cells overexpress (produce too much) PCA3. It can be measured in urine and in prostate fluid following prostate massage or DRE. The PCA3 test is useful in assessing the risk of prostate cancer on repeat biopsy (European Urology, PMID 21871709; Prostate Cancer and Prostatic Diseases, PMID 22042252).
Diagnosis
A key area of research activity involves developing better ways to diagnose and stage prostate cancer.
Noteworthy research includes:
- Doctors commonly use transrectal ultrasound (TRUS) to help them guide the needle during a prostate biopsy. A better form of ultrasound, called power Doppler ultrasound, measures the patterns of blood flow in the prostate gland. Researchers have shown that power Doppler ultrasound improves doctors’ ability to distinguish prostate cancer from benign hypertrophy of the prostate (BJU International, PMID 19888980; DerRadiologe, PMID 22083309).
- The role of magnetic resonance imaging (MRI) in the diagnosis and staging of prostate cancer is expanding quickly. MRI-targeted biopsy is a test that uses MRI to guide the needle during biopsy of a suspicious area of the prostate. This technique may be more accurate in detecting prostate cancer than the standard prostate biopsy (BJU International, PMID 21426475; European Urology, PMID 22137601; Radiology Research and Practice, PMID 22091382). MRI may also help doctors to better determine which men might benefit from active surveillance. (The Journal of Urology, PMID 22335871, PMID 21849184).
Prognostic factors
Prognostic factors that may help determine the outcome of the disease are being studied in prostate cancer. They can be used to predict the chances of recovery or of cancer coming back. Doctors may also use prognostic factors to help them make treatment recommendations.
Noteworthy research includes:
- Various biomarkers are showing promise in predicting how prostate cancer will behave.
- B7-H3 is a newly discovered tumour marker that is overexpressed by prostate cancer cells. Increasing levels of B7-H3 are associated with worsening or more aggressive disease (International Journal of Radiation Oncology, Biology, Physics, PMID 20598810; The Journal of Urology, PMID 21784485).
- Researchers have discovered new gene abnormalities in the tumours of some men with prostate cancer. In about half of all prostate cancers, the prostate-specific TMPRSS2 gene and the ERG gene is fused (referred to as TMPRSS2:ERG). This gene fusion may be helpful in determining prognosis in men with prostate cancer (Expert Review of Anticancer Therapy, PMID 20014889; Clinical Cancer Research, PMID 19825963; BMC Cancer, PMID 22142399; Science, PMID 16254181).
- Other biomarkers have proven to be useful in determining prognosis in men who have had a prostatectomy (surgical removal of the prostate). These biomarkers include Ki-67 and MDM2 (cellular markers for cell growth). Increased expression of these biomarkers was associated with a high Gleason score (a system used to describe the grade of prostate cancer) and short progression-free survival (Journal of Clinical Oncology, PMID 19470936; Public Library of Science One, PMID 21629784). High RBM3 (a protein involved in cell survival) expression in prostate cancer indicated a lower risk of biochemical recurrence (rise in PSA level during follow-up of prostate cancer) of prostate cancer and progression (Diagnostic Pathology, PMID 21955582).
Treatment
Researchers are looking for new ways to improve the treatment of prostate cancer. Advances in cancer treatment and new ways to manage the side effects related to treatment have improved the outlook and quality of life for many people with cancer.
Noteworthy research includes:
- Many men with early stage, low grade, focal small-volume prostate cancer may receive active surveillance (very close monitoring). They are treated only if their cancer progresses (determined by changes in PSA level, Gleason score on prostate biopsies, symptoms or other test results). Active surveillance as a treatment option has gained increasing acceptance with better clinical guidelines (ArchivosEspañoles de Urología, PMID 22052761; Journal of Clinical Oncology, PMID 19917860).
- The PIVOT trial was a randomized trial of more than 700 men. It showed that active intervention did not have better survival rates than active surveillance, except in cases of high-risk disease.
- A number of Canadian centres have introduced robotic prostatectomy, which is a type of laparoscopic prostatectomy. Robotic prostatectomy is an expensive procedure, and researchers have not done randomized studies to test it. Robotic prostatectomy has shown consistent improvements over standard (open) radical prostatectomy surgery, including a shorter hospital stay, less blood loss during surgery and a shorter recovery time before regular activities are resumed. Most studies show that robotic prostatectomy had the same cancer control rates and the rate of side effects (such as decreased sexual function or incontinence) than standard (open) radical prostatectomy (Journal of Urology, PMID 20083261; JAMA: The Journal of the American Medical Association, PMID 19826025; Technology and Health Care, PMID 22027152; Prostate Cancer, PMID 22110994).
- Men who had a prostatectomy may benefit from adjuvant radiation therapy.
- A recent North American study showed that men whose prostate cancer has spread to the prostate capsule or seminal vesicles, and men with positive surgical margins, had improved survival when they received radiation therapy after surgery. Researchers are now waiting for long-term follow-up results (Cochrane Database of Systematic Reviews [Online], PMID 22161411; Journal of Clinical Oncology, PMID 19433689; JAMA: The Journal of the American Medical Association, PMID 17105795; Lancet, PMID 16099293).
- Radiation therapy after surgery appears to be beneficial in treating prostate cancer. It is still unclear whether giving radiation at the time of the first PSA rise after surgery (early salvage) is as effective as giving radiation immediately after surgery. Some men never have a PSA rise, so delaying radiation therapy for a period of time after surgery may spare these men from receiving radiation and the associated side effects. The Radiotherapy and Androgen Deprivation in Combination after Local Surgery (RADICALS) study is a clinical trial across Canada and the UK which is investigating the timing of adjuvant radiation therapy (immediate versus time of first PSA rise) and the role of hormonal therapy in men after surgery for prostate cancer (BJU International, PMID 17428247).
- Researchers compared radiation therapy combined with long-term adjuvant hormonal therapy versus short-term hormonal therapy for prostate cancer. They found that radiation therapy and long-term hormonal therapy showed significant improvement in disease-free and disease-specific survival, local progression, distant metastasis and biochemical failure in men with locally advanced prostate cancer. A large European trial found an improvement in overall survival with 3 years of adjuvant hormonal therapy compared to 6 months of hormonal therapy (New England Journal of Medicine, PMID 19516032; Endocrinology and Metabolism Clinics of North America, PMID 21889724).
- Several studies have shown the potential side effects of hormonal therapy for prostate cancer. The list of side effects from hormonal therapy includes an increased risk of diabetes, cardiovascular disease and fatal heart attack (myocardial infarction). Hormonal therapy may be given to men with metastatic, recurrent or high-risk prostate cancer (Journal of the National Cancer Institute, PMID 19996060; JAMA: The Journal of the American Medical Association, PMID 19706860, PMID 22147380; Therapeutic Advances in Urology, PMID 21789093).
- Researchers are studying newer hormonal therapies for men with prostate cancer. Degarelix (Firmagon) is a luteinizing hormone–releasing hormone (LHRH) antagonist. It prevents the release of luteinizing hormone. When there is less luteinizing hormone in the body, the testicles will not release testosterone. The reduction in testosterone stops the prostate cancer cells from growing. Some hormonal therapy drugs may cause a brief increase in the testosterone levels (testosterone surge), which can worsen symptoms (tumour flare reaction). Men who took degarelix had lower rates of PSA rise and no testosterone surge compared to those taking the LHRH agonist leuprolide (Lupron, Lupron Depot, Eligard). Larger studies are needed to determine if degarelix gives a survival advantage (European Urology, PMID 19962227). Researchers are also testing other LHRH antagonists, including abarelix (Plenaxis), ganirelix (Antagon) and cetrorelix (Cetrotide), as potential hormonal treatments for prostate cancer (Therapeutic Advances in Urology, PMID 21904569).
- A trial led by the NCIC Clinical Trials Group, which is funded by the Canadian Cancer Society, found that men with PSA recurrence after radical prostatectomy for prostate cancer who are treated with intermittent hormonal therapy live as long as those who receive continuous therapy. The results of this trial are expected to change current treatment protocols and reduce some of the side effects of hormone therapy, including impotence. The findings were presented at the annual meeting of the American Society of Clinical Oncology (ASCO), where the research was selected as the “Best of ASCO” (ASCO**, Abstract 4514). A European randomized phase III study found that men with advanced prostate cancer who received intermittent hormonal therapy had similar survival outcomes as those who received continuous hormonal therapy. Men who received intermittent hormonal therapy had fewer side effects and better sexual function (European Urology, PMID 19249153).
- Researchers are looking at better ways to give external beam radiation therapy to men with prostate cancer. They are studying several methods that try to give radiation only to the prostate gland and prevent radiation damage to the surrounding structures. Researchers are studying a new type ofintensity-modulated radiation therapy (IMRT), called volumetric modulated arc therapy (VMAT), in men with prostate cancer. The main advantage of VMAT is that the radiation can be given faster and possibly more precisely than other forms of radiation therapy (International Journal of Radiation Oncology, Biology, Physics, PMID 21543164).
- Approximately 75% of cancers occur as more than one tumour (multifocal), but there is often one dominant tumour that is likely to determine the overall course of the cancer. Focal therapy is used to treat small, low-risk and intermediate-risk prostate tumours. This treatment uses cryosurgery, laser or high-intensity focused ultrasound (HIFU) to treat only one-half of the prostate gland or only the tumour within the prostate gland. This therapy has been called the “male lumpectomy.” This approach aims to spare the normal prostate tissue to prevent complications that can occur with routine prostate cancer treatments, such as incontinence and impotence. Some doctors are concerned that these men may be best suited for active surveillance and that focal therapy is overtreatment. Further study and long-term follow-up are needed to determine the use of this approach in prostate cancer treatment (The Prostate, PMID 22161896; ArchivosEspañoles de Urología, PMID 22052762).
- High-intensity focused ultrasound (HIFU) is a minimally invasive procedure that uses ultrasound waves focused to create intense heat, which destroys tissue. The procedure is intended to be a primary treatment for men with localized prostate cancer. It has also been used as a salvage therapy after radiation therapy. However, a new study shows that this treatment carries a high risk of local side effects (Cancer, PMID 22071795). HIFU is a procedure that can be repeated. There is a lack of quality long-term data to show that it is as effective as standard therapy (British Journal of Cancer, PMID 19513068; The Canadian Journal of Urology, PMID 21504653; European Urology, PMID 18508188). HIFU is not widely available in Canada and is not currently covered by provincial healthcare plans.
- Cryosurgery, also known as cryoablation, is a minimally invasive procedure that destroys prostate cancer cells through a process of freezing and thawing. Cryosurgery is used as primary and salvage treatments for men with localized prostate cancer. Researchers have shown that it reduces local toxicity and damage to surrounding tissues, but there is a lack of data to support its routine use (Current Opinion in Urology, PMID 19195130). Cryosurgery to the entire prostate can, however, lead to a high rate of impotence (BJU International, PMID 18793299).
- Researchers have found that salvage radical prostatectomy was more effective than salvage cryosurgery in treating local recurrence after radiation. Cryosurgery is an attractive option because it appears to have significantly fewer side effects than salvage surgery, but there are concerns that it might not cure the cancer as effectively as surgery (Journal of Urology, PMID 19524984).
- New drugs, such as abiraterone and MDV3100, have led to significant improvements in the treatment of prostate cancer that has become resistant to traditional hormonal therapy (The New England Journal of Medicine, PMID21612468; ASCO, Abstract LBA1; Current Opinion in Supportive and Palliative Care, PMID 21734586; Current opinion in Oncology, PMID 21311328).
- Cancer vaccines are designed to stimulate the body to produce an immune response against cancer cells. Two phase III clinical trials have shown that the cancer vaccine sipuleucel-T (Provenge)improves survival in men with advanced prostate cancer. It is FDA approved for use in USA. Researchers are also testing another vaccine, PROSTVAC-VF, in early phase clinical trials (Journal of Clinical Oncology, PMID 20100959; Vaccine, PMID 22122856; European Urology, PMID 22001436, PMID 22036643; Expert Opinion on Biological Therapy, PMID 21675925).
- Researchers are studying dutasteride (Avodart) to find out if it may have a role in the treatment of early stage prostate cancer (Urology, PMID 20472268; Lancet, PMID 22277570).
Supportive care
Living with cancer can be challenging in many different ways. Supportive care can help people cope with cancer, its treatment and possible side effects.
Noteworthy research includes:
- A study found that men who are obese and physically inactive before surgery for prostate cancer have higher rates of incontinence than men who are physically active and at a healthy weight. Men who become physically active and lose weight before surgery may help to reduce their risk of incontinence (Journal of Urology, PMID 20018324).
- Denosumab(Xgeva) is a type of monoclonal antibody that can strengthen bones and prevent osteoporosis in men taking hormonal therapy for prostate cancer. Researchers have shown that denosumab increases bone density in men, including those who are most at risk for bone fractures and bone loss, and delays bone metastases (ASCO, Abstract 6; Lancet, PMID 22093187; Drugs of Today, PMID 21850283). Toremifenecitrate (Acapodene) was also found to strengthen bones and prevent fractures in men taking hormonal therapy for prostate cancer (ASCO, Abstract 4676; The Journal of Urology, PMID 22014807).
*PMID is the National Library of Medicine PubMed abstract identity number.
**ASCO is the American Society of Clinical Oncology.
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