doctor's orders: speak up and get screened for prostate cancer
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why and how prostate cancer strikes comes down to genetics and environmental exposure over time.
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as men age, it’s common for them to develop an enlarged prostate. what starts out as a gland the size of a walnut can become more like a plum or a peach, putting pressure on the urethra that can cause urinating and sexual difficulties. it’s considered a delicate area of the body that can bring on symptoms that men often don’t want to talk about.
these can also be signs of prostate cancer, which is the most common cancer in canadian men, and the second leading cause of death from cancer for canadian men. the disease claims nearly 5,000 lives every year, according to the canadian cancer society, and one in eight men will develop it in their lifetime. it is also one of the most survivable cancers because of its uniquely slow-moving progression. screening and early detection, along with advanced treatments, mean that men with prostate cancer are living longer, better lives.
but when the disease is diagnosed late and may have spread to other areas of the body, just three in 10 patients are expected to live another five years.
dr. martin gleave, professor and chair of urological sciences at the university of british columbia where he is also co-founder and director of the vancouver prostate centre, has led the development of new treatments for prostate cancer and studied its resistance to treatment. he sees firsthand the need for awareness and education so people won’t shy away from talking about their prostate with health-care providers and get screened.
“prostate cancer is a disease of aging. and canada, like other western countries, has continued to enjoy increasing longevity. so prostate cancer is the most common cancer that affects aging men, second only to lung cancer in death from cancer. of all cancers, its prevalence increases the most dramatically with age,” gleave says.
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“as our population ages, we have to be more worried about the diseases that accumulate with age. this wasn’t a problem 100 years ago. as we deal with other things that shorten our lives, like neurodegenerative diseases and cancers in particular, prostate cancer becomes more of a population health problem.”
prostate cancer causes and prevention: a lesson in 2022年世界杯名单猜测
why and how prostate cancer strikes comes down to genetics and environmental exposure over time. alterations in dna that you’re either born with or develop, cause what gleave describes as a dysregulated “cell growth invasion” where multiplying cells in the prostate form tumours that damage surrounding tissue or spread to other parts of the body. having prostate cancer or other cancers in the family is a risk factor, but cell damage accumulated from environmental causes can include a range of factors.
gleave explains that environmental determinants can be physiologic, meaning it’s within your own body, driven by sex hormones including testosterone. then there are diet and lifestyle habits that may predispose people to a higher chance of prostate cancer. for example, the western diet tends to be high in animal fats, refined grains and highly processed foods that have been shown to cause inflammation.
“these are all risk factors that account for varying degrees of causality,” he says, stressing that nothing is absolute with the disease pathology. “many people are vegetarians and have no family history and yet still develop prostate cancer. it’s just the way that the deck of cards that you were born with was dealt.”
the best prevention is focusing on things that you have control over, like a well-balanced diet, regular physical activity, not smoking and maintaining a healthy weight, all which also help to stave off other age-related diseases, he advises.
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and if you develop prostate cancer, good general health is important because you will be fitter and better able to deal with treatments or surgery. “it’s all bundled together. the responsibility of maintaining ideal body weight and a healthy lifestyle helps you deal with the threats that you’re going to be confronted by as you age.”
dr. martin gleave
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his most important message about prostate cancer is early detection before it causes symptoms like back, hip or rib pain that usually happens when the cancer has already metastasized. gleave also points out that changes in urination to a slow, weak stream are more commonly caused by aging and the benign enlargement of the prostate than prostate cancer.
prostate cancer screening: when to get screened and what to expect
on that note, gleave says screening for prostate cancer has advanced substantially in recent years. guidelines recommend a prostate-specific antigen (psa) test beginning at age 50, with those at high risk because of a family history of cancer to start screening at age 45. psa screening is a blood test that looks for a specific protein produced by prostate cells. a small amount of this protein in the blood is not unusual, where you wouldn’t need another psa for a few years. if your psa is elevated, the test may be repeated.
psas are not one-and-done tests. “what’s important is that it’s a continuous variable that we measure serially over time, where the rate of change over time represents a very important predictor of risk as well,” gleave says.
if psa continues to be elevated, magnetic resonance imaging (mri) would follow. “fifteen years ago, if psa was elevated, they all got a biopsy. but now we have a way to use mri to identify those with borderline elevations in psa, and if you get an mri and it’s normal, you don’t need a biopsy,” he adds.
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if the mri flags an abnormality and a biopsy is recommended, new procedures can image-guide the needle into the area so the biopsy is more accurate and precise, allowing for a greater chance of detecting the higher-grade lesions specialists are seeking to diagnose. results lead to three scenarios, he explains: one, it’s all benign and the patient continues to be monitored. two, it identifies low-grade cancer, which is the type of cancer that does not need treatment and then the patient is monitored with “active surveillance.” or three, higher-grade cancer is detected, and further testing, such as ct and bone scans, and intervention becomes necessary.
while there’s controversy about the accuracy of psa screening, gleaves says that it’s effective from a patient risk/benefit point of view to identify those who need treatment at a time when they’re ideally curable.
there are also strides in precision oncology where, for example, the use of a psma pet scan can highlight the extent of the cancer so more precise treatment recommendations can be made. psma pet works by injecting a radioactive tracer which attaches itself to proteins known as prostate-specific membrane antigens (psma). because prostate cancer tumours have these proteins on their surface, doctors can pinpoint their location with the tracer.
prostate cancer treatment options: surgery, radiotherapy and immunotherapy
treatment options for higher-grade cancer usually require either surgical removal of the prostate gland – a radical prostatectomy – or various types of radiotherapy to destroy prostate cancer cells.
“both have their pros and cons, and both have reasonably good cure rates. and then we monitor patients after that for recurrence with psa determinations,” he says. “as long as the psa is low and not rising, then they’re in remission, but if the level starts to rise, then we again look for metastatic recurrence with scans. once the cancer has recurred, then we have to turn toward systemic therapies.”
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these systemic or system-wide therapies circulate and attack cancer cells throughout the body, and can be a targeted combination of hormone therapy, chemotherapy and other agents to treat the metastatic disease. gleave’s specialty is late-stage prostate cancer treatment. for example, he’s co-authored recently published research on systemic targeted therapy that looks at genome sequencing in advanced prostate cancer and biomarkers that hold promise as therapeutic targets.
another study in modern pathology investigated ai automated detection of a specific protein called phosphatase and tensin homolog, or pten, that acts as a tumour suppressor that becomes mutated at a high frequency in a number of cancers including prostate cancer. detection and analysis of pten can be used as an early predictor of prostate cancer metastasis after surgery.
immunotherapy is another emerging class of treatments that stimulates the person’s immune system to help kill cancer cells. however, in prostate cancer there are limitations.
“prostate cancer is a cold tumour, while some cancers like colorectal, lung, and melanoma in particular, are immune-hot, which means that they respond to immune therapies,” gleave says. “prostate is immune-cold. even if you treat with immune therapies, you don’t get activation of the immune response because the prostate cell is able to suppress the immune system in its microenvironment.”
but ongoing research has contributed to prostate cancer survival rates more than doubling over the past two decades, and those with high-advanced disease are living six years after treatment or longer. gleave credits early detection for increasing the pool of highly curative people, and the fact that people who present with locally advanced cancers are benefitting from “multimodal therapy” which includes surgery, radiation and systemic therapies.
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new drugs have pushed the ability to prolong survival, including new hormone therapies and recently approved parp inhibitors. parp proteins in cells repair cell damage, so the parp inhibitors stop these proteins from doing their repair work in cancer cells and the cells die. there is also psma-directed radiation therapy that targets and destroys prostate cancer cells only, sparing healthy tissue.
“we’ve got better surgery and convergent advances in imaging so we are better able to detect and define the extent of cancer. we also have better understanding of the biology through genomic biomarkers,” he explains of the move to precision oncology in the field.
specialists now have all this information to tailor treatments for each patient and combine novel drugs based on genomic biomarkers.
“i want to emphasize that it’s convergence that makes the advances happen because of the interdisciplinary nature of science and medicine. and that’s where biologists and engineers and computer scientists and doctors are all interacting and communicating more than we ever did before.”
to learn more about prostate cancer, visit the canadian cancer society and procure charitable organization.
karen hawthorne is a toronto-based writer.
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