Research in prostate cancer
We are always learning more about cancer. Researchers and healthcare professionals use what they learn from research studies to develop better practices that will help prevent, find and treat prostate cancer.
The following is a selection of research showing promise for prostate cancer. We’ve included information from PubMed, which is the research database of the National Library of Medicine (NLM). Each research article in PubMed has an identity number (called a PMID) that links to a brief overview (called an abstract). We have also included links to abstracts of the research presented at meetings of the American Society of Clinical Oncology (ASCO), which are held throughout each year. Information about ongoing clinical trials in Canada comes from the Canadian Clinical Trials website or ClinicalTrials.gov. Clinical trials are given an NLM identifier called a national clinical trial (NCT) number. The NCT number links to information about the clinical trial.
Reducing the risk of prostate cancer
Some substances or behaviours may lower your risk of developing prostate cancer. The following is noteworthy research into ways to lower your risk.
Metformin is a drug used to treat diabetes. A recent study found that men on metformin had a statistically lower risk of developing prostate cancer, while men on other diabetes medicines did not (European Urology, PMID 24857538). But another study found that metformin did not lower the risk in men who took it (European Journal of Cancer, PMID 25727881). More research is needed to find out if metformin has a role in preventing prostate cancer.
Statin drugs are used to lower cholesterol. Researchers studied statin drugs, aspirin, metformin and insulin to see if they lowered the risk of prostate cancer. They found that none of these drugs lowered the risk of prostate cancer. But using statin drugs increased a man’s risk of developing high-grade prostate cancer (European Journal of Cancer, PMID 25727881).
Lycopene is a type of antioxidant called a carotenoid. A recent review and meta-analysis (a large research study that looks at the results of several individual studies) looked at lycopene research. It suggested that men who took in higher amounts of lycopene from their diet had a lower risk of developing prostate cancer (Medicine, PMID 26287411). More research is needed to understand how lycopene may lower the risk of prostate cancer or if there are other substances that can be combined with lycopene to reduce the risk.
Find out more about research in reducing the risk of cancer.
Screening tests help find prostate cancer before any signs or symptoms develop. When cancer is found and treated early, the chances of successful treatment are better. The following is noteworthy research into screening for prostate cancer.
The Stockholm 3 Model (STHLM3) combines personal factors and several tests, including the prostate-specific antigen (PSA) test. Researchers are looking at STHLM3 as a screening test for prostate cancer. A recent study found that it can identify men who have a higher risk for prostate cancer, which can lower the number of biopsies done to look for prostate cancer. (Lancet Oncology, PMID 26563502). Further study is needed to find out what role STHLM3 may have in screening for prostate cancer.
Prostate-specific antigen velocity (PSA-V) measures changes in the level of PSA over time. The IMPACT clinical trial used PSA-V in men with a known genetic risk for developing prostate cancer. Results suggest that men whose PSA levels change by more than 0.75 ng/mL over a year have a higher risk of developing prostate cancer. The trial also found that men with BRCA gene mutations who had this increase in PSA levels had an even higher risk of developing prostate cancer than men with other genetic risk factors. The IMPACT trial also found that PSA-V could predict which tumours would have a Gleason score of 7 or higher (ASCO, Abstract 16).
Find out more about research in screening and finding cancer early.
Diagnosis and prognosis
A key area of research looks at better ways to diagnose and stage prostate cancer. Researchers are also trying to find ways to help doctors predict a prognosis (the probability that the cancer can be successfully treated or that it will come back after treatment). The following is noteworthy research into diagnosis and prognosis.
Researchers are studying the following imaging tests to see if they can help diagnose prostate cancer.
Contrast-enhanced ultrasound (CEUS) uses a contrast medium to help structures in the body to show up better during an ultrasound. A meta-analysis found that CEUS shows promise as a diagnostic test for prostate cancer, but doctors still need to do a biopsy to confirm the diagnosis (Academic Radiology, PMID 23103186). More study is needed to find the best type of contrast medium and ultrasound technique, as well as the role CEUS will have in diagnosing prostate cancer (Sensors, PMID 25734645).
MRI ultrasound fusion–guided biopsy combines MRI and ultrasound to make very detailed 3-D pictures of the prostate from many different angles (called a multiparametric image). The detailed images help doctors target specific areas in the prostate to take biopsy samples. Research shows that this type of diagnostic test helps find prostate cancer earlier (ASCO, Abstract 155).
Biomarkers are substances, such as proteins, genes or pieces of genetic material like DNA and RNA, that are naturally in the body. They can be measured in body fluids like blood and urine or tissue that has been removed from the body. A gene mutation or a change in the normal amount of a biomarker can mean that a person has a certain type of cancer.
Researchers are looking at the following biomarkers to see if they can help doctors diagnose, predict a prognosis for and find out which treatments will benefit a man with prostate cancer:
- PCA3 (Journal of Experimental Clinical Cancer Research, PMID 25651917)
- ephrin-A2 (Tumour Biology, PMID 26561474)
Gene-based tests find differences between normal genes and genes that are changed, or mutated, in cancer cells. Microarray analysis is a type of gene-based test that allows researchers to look at many genes together to see which ones are turned on and which ones are turned off. Analyzing many genes at the same time to see which are turned on and which are turned off is called gene expression profiling. Researchers hope that developing more gene-based tests will help doctors identify the best treatments for certain cancers, including prostate cancer. Gene-based tests will also help doctors tailor more treatments to each person’s cancer based on their unique genetic makeup.
Prolaris, Decipher and Oncotype DX are 3 different gene-based tests that may be used to help diagnose prostate cancer. A recent review of research studies found that these tests do not always find prostate cancer and so shouldn’t be used as a standard diagnostic test. More research is needed to find out if they should be used as prognostic or predictive tools for prostate cancer (ASCO, Abstract 135).
A 30-gene expression test may help identify prostate cancer that has a low risk of spreading quickly. A study looked at this test in men with prostate cancer and a Gleason score of 7. Results showed that the test could accurately identify prostate cancer that had a high or low risk of progressing. Knowing that a prostate cancer has a low risk of progressing will allow doctors to use active surveillance instead of giving unnecessary treatment, which can avoid the harmful side effects from treatments such as surgery or radiation therapy (ASCO, Abstract 10).
A system of 5 prognostic grade groupings (PGGs) may be used instead of the Gleason score to identify how likely prostate cancer is to recur after treatment. The Gleason score is the most commonly used grading system for prostate cancer. It describes how aggressive prostate cancer is and how likely it is to spread. Experts worry that the Gleason system may lead to overtreatment, which means that doctors give more treatment for prostate cancer than they need to. PGG categories translate the Gleason score into 5 risk categories. Studies show that the PGG categories may help avoid overtreatment for prostate cancer, but more study is needed (European Urology, PMID 26563871; PMID 26166626).
Find out more about research in diagnosis and prognosis.
Researchers are looking for new ways to improve treatment for prostate cancer. Advances in cancer treatment and new ways to manage the side effects from treatment have improved the outlook and quality of life for many men with cancer. The following is noteworthy research into treatment for prostate cancer.
Alternatives to surgery
Surgery is a standard treatment for prostate cancer, but some men may not be healthy enough to have surgery. Research is looking at different treatments that can be used instead of surgery.
Cryosurgery uses extreme cold (liquid nitrogen or carbon dioxide) to freeze and destroy abnormal cells or tissue. One study looked at using cryosurgery as the main treatment for prostate cancer that has not spread outside of the prostate. Results suggest that cryosurgery can provide long-term control of the cancer and may be a treatment option for some men (ASCO, Abstract 114). Cryosurgery may also be an option for men with prostate cancer that comes back, or recurs, in the same area that it started (Prostate, PMID 25283814).
High-intensity focused ultrasound (HIFU) uses concentrated high-frequency sound waves to heat up and destroy tissues. Researchers are looking at HIFU as a treatment for prostate cancer. They are comparing HIFU to standard treatments to see if it is a safe and effective treatment option (Progrès en Urologie, PMID 26476975; Advances in Urology, PMID 26357511; ASCO Abstract 109).
Researchers are looking at new and better ways to deliver radiation therapy. They are also trying to find out if radiation can be combined with other treatments to make them both more effective.
CyberKnife is a machine used in stereotactic radiation therapy. It focuses very precise beams of radiation at the area being treated. One study used CyberKnife to destroy the prostate gland as a treatment for prostate cancer that had a low risk of coming back, or recurring. Results suggest that CyberKnife is safe and effective. It also increases the amount of time before men need to start androgen deprivation therapy (ADT), which is a type of hormonal therapy. Another advantage of using CyberKnife to destroy the prostate is that this treatment takes less time than other types of radiation therapy (Central European Journal of Urology, PMID 26568868). Another small study looked at using CyberKnife to treat prostate cancer that comes back in lymph nodes near the prostate. It found that CyberKnife may be an effective treatment for prostate cancer that comes back in these lymph nodes, but more research is needed (ASCO, Abstract 257).
Radiation therapy or active surveillance are 2 treatment options that may be used after surgery to remove the prostate. Experts don’t agree which one is best for stage T3 tumours or when cancer cells are found in the tissue removed along with the tumour (called positive surgical margins). A recent review looked at 3 clinical trials that compared radiation therapy after surgery (called adjuvant radiation therapy) to watching for signs of recurrence and not giving treatment after surgery until the cancer returned (called active surveillance). This review shows that more men who received adjuvant radiation therapy survived 10 years without the cancer spreading to other parts of the body (called metastases) than men who received active surveillance. But both groups had the same 10-year survival rate (ASCO, Abstract 19).
Low-dose-rate brachytherapywith iodine-125 was compared to external beam radiation therapy to find out which was better as a radiation boost after external beam radiation to all of the pelvis. The Canadian trial found that the brachytherapy was more effective than external beam radiation therapy in men with prostate cancer that had a higher risk for recurrence (ASCO, Abstract 03).
Radiation therapy combined with hormonal therapy may be a treatment option for prostate cancer that has an intermediate risk for recurrence. A Canadian clinical trial compared giving bicalutamide (Casodex) and goserelin (Zoladex) with radiation therapy for 6 months to giving radiation therapy alone. Results show that it took longer for PSA levels to rise, or for prostate cancer to come back when men received both treatments. But both groups had the same survival rate (ASCO, Abstract 05).
Find out more about research in radiation therapy.
Hormonal therapy is often used to treat prostate cancer. Researchers are looking for new hormonal therapy drugs and the best way to use them to treat prostate cancer.
ODM-201 is a new type of drug that lowers the amount of androgen in the body. The ARAMIS clinical trial is a large international trial that is trying to find out how safe and effective ODM-201 is in preventing high-risk prostate cancer from spreading to other parts of the body (NCT 02200614).
Bicalutamide (compared to a placebo) improved overall survival for men with prostate cancer that had spread into the area around the prostate (called locally advanced cancer). Men with high PSA levels at the beginning of treatment benefited the most from bicalutamide because they lived longer. But men who had prostate cancer that had not spread outside the prostate gland did not survive longer when they were given bicalutamide rather than a placebo (ASCO, Abstract 02).
Researchers are looking at new drugs to treat prostate cancer. They are also trying to find out if chemotherapy can be combined with other treatments to make treatment more effective.
Custirsen is a new drug that stops the production of the protein clusterin, which helps prostate cancer cells become resistant to treatment. A recent clinical trial looked at docetaxel with or without custirsen to treat castrate-resistant prostate cancer that had a poor prognosis. (Castrate-resistant prostate cancer means that it has stopped responding to hormonal therapies.) Results suggest that adding custirsen to docetaxel may slightly improve survival (ASCO, Abstract 5009).
The combination of chemotherapy, hormonal therapy and radiation therapy was compared to hormonal therapy and radiation therapy as treatment for cancer that had not spread outside the prostate (called localized cancer) but that had a high risk of recurring. The chemotherapy used was docetaxel (Taxotere) and prednisone. Results suggest that adding chemotherapy to hormone therapy (ADT) and radiation therapy improved overall survival. More research and longer follow-up is needed to confirm these results (ASCO, Abstract LBA5002).
Docetaxel and zoledronic acid (Zometa), a type of bisphosphonate, may be treatment options for men who haven’t received hormone therapy for prostate cancer. The STAMPEDE trial compared 3 groups. When starting hormone therapy, the 1st group was given docetaxel, the 2nd group was given zoledronic acid and the 3rd group was given both drugs. The study showed that giving docetaxel at the start of hormonal therapy significantly improved survival, but adding zoledronic acid did not (ASCO, Abstract 5001).
Find out more about research in chemotherapy.
Biological and targeted therapy
Researchers are developing and testing biological therapies and targeted therapies to find more effective ways of treating prostate cancer.
Cabozantinib (Cometriq) is a type of tyrosine kinase inhibitor. A clinical trial compared cabozantinib to prednisone in men who had already been treated with docetaxel, abiraterone acetate (Zytiga) or enzalutamide (Xtandi). Doctors did bone scans after these treatments. They found that men treated with cabozantinib had fewer tumours than men treated with prednisone. Men treated with cabozantinib also lived longer without the prostate cancer getting worse (called progression-free survival). Cabozantinib only improved overall survival for men whose prostate cancer had spread to the lungs, liver or other soft tissues (ASCO, Abstract 139).
Therapeutic vaccines may be a treatment option for castrate-resistant prostate cancer that has spread to other parts of the body. Researchers are developing several vaccines and studying them in clinical trials. These vaccines include PROSTVAC, DCVAC/PCa and PSA-TRICOM (Therapeutic Advances in Vaccines, PMID 25177493; ASCO, Abstract TPS5070, Abstract TPS 5081; Future Oncology, PMID 26235179).
Find out more about research in biological and targeted therapy.
Learn more about cancer research
Researchers continue to try to find out more about prostate cancer. Clinical trials are research studies that test new ways to prevent, detect, treat or manage prostate cancer. Clinical trials provide information about the safety and effectiveness of new approaches to see if they should become widely available. Most of the standard treatments for prostate cancer were first shown to be effective through clinical trials.
A yellow, orange or red substance found mostly in plants, including yellow and orange fruits and vegetables (such as carrots and sweet potatoes), as well as in dark green, leafy vegetables (such as spinach and kale) and some grains. The body changes some carotenoids into vitamin A.
Carotenoids include beta carotene, lutein and lycopene.
Carotenoids are a type of phytochemical that have antioxidant effects. Researchers are studying the role of carotenoids in preventing cancer.
BRCA1 and BRCA2 genes are tumour suppressor genes. Changes to genes are called mutations. Mutations of the BRCA genes are inherited from one or both parents, and these mutations increase the risk of cancer.
Women with BRCA mutations have a higher risk of breast and ovarian cancers. Men with BRCA mutations also have a higher risk of breast cancer, and may have a higher risk of prostate cancer. The risk of other cancers – such as stomach or pancreatic cancer – may also be higher with BRCA mutations.
A system used to describe the grade of prostate cancer based on how the cancer cells look and behave when viewed under a microscope.
When examined under a microscope, prostate cancer cells can be classified with different grades (from 1 to 5). The pathologist examines a sample of prostate tissue and determines the first and second most common grades in the sample. These grades are added to determine the Gleason score. The prostate cancer is assigned to 1 of 3 risk groups (low, intermediate and high) based on the Gleason score.
Also called Gleason classification or Gleason scale.
A type of external radiation therapy that uses special equipment to aim high-energy radiation beams at a tumour from different directions.
Stereotactic radiation therapy is used to treat tumours in the brain and other parts of the body. A special frame is used to make sure the person receiving treatment does not move and to ensure that radiation is delivered to exactly the same place during each treatment.
Stereotactic radiation therapy may be delivered as stereotactic radiosurgery or stereotactic radiotherapy.
Also called stereotactic external-beam radiation therapy and stereotaxic radiation therapy.
A harmless, inactive substance or treatment that looks the same as, and is given in the same way as, an active drug or treatment.
Placebos may be used in controlled clinical trials. One group is given a placebo and the other is given the substance or treatment being studied, then researchers compare the effects of the placebo and the active substance or treatment.
A drug that blocks the actions of the enzyme tyrosine kinase, which helps transmit the signals that occur after a growth factor binds to its receptor. Tyrosine kinase is involved in cell communication, development, division and growth.
Tyrosine kinase inhibitors are a type of growth factor inhibitor therapy. They may be used to help prevent tumour growth.
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