November is Prostate Cancer Awareness Month, so this month we’ve interviewed MiraKind’s founder, Dr. Joanne Weidhaas, about prostate cancer treatment and how patients can personalize their treatment choices with a new diagnostic test called PROSTOX, developed by MiraDX and accessible through MiraKind.
Dr. Joanne Weidhaas, MD, PhD, is an oncologist and scientist who is passionate about improving cancer patients’ lives through research and the application of newly discovered scientific breakthroughs to healthcare. In 2006, Dr. Weidhaas co-discovered the KRAS-variant, the first of a new class of inherited genetic biomarkers with broad implications in human health.1
She founded MiraKind to educate individuals about these biomarkers, to advance research to help prevent and better treat disease, and to enable patients to have access to this meaningful genetic information.
Q: How is prostate cancer typically treated?
Dr. Weidhaas: Once a prostate cancer patient needs to receive treatment, they have several options including several types of radiation therapy, or surgery.
Q: What factors influence the treatment choice for prostate cancer?
Dr. Weidhaas: If the cancer is more advanced, or has extended outside of the prostate, radiation is generally recommended because it can cover more areas.
Treatment for localized prostate cancer is often based on the patient’s preference. There has not been a lot of guidance on which treatment to choose because the cure rates from surgery and radiation are the same, and studies show that the side effects and their rates are pretty similar.
Q: What are prostate cancer patients’ biggest concerns when choosing a treatment?
Dr. Weidhaas: Most patients’ number one concern, when deciding on treatment, is the risk of side effects – what they may be, which ones they are willing to tolerate, and what their chances are of having them.
Prostate cancer is one of the few cancers where patients usually have time to figure out their treatment choice because, generally, it is a slow-growing cancer that does not need to be treated immediately. The other good news is that there are several good treatment options, so if one is not a good choice for a patient, there are other excellent treatment choices.
Q: What is prostate cancer radiation therapy, and how does it work?
Dr. Weidhaas: The most common way we give radiation therapy is by using radiation beams from outside of the body, called external beam radiation. Those beams are like high-powered X-rays that are really focused on the area that needs to be treated. In this case, the full prostate is treated.
There are two main ways to give external beam radiation. Big doses over 5-7 days, called stereotactic body radiotherapy (SBRT), or smaller doses over 5-8 weeks, called conventionally fractionated radiotherapy (CFRT).
The other form of radiation that can be used for prostate cancer is brachytherapy, where they put the radiation inside the prostate and they can either leave the radiation in there permanently or insert it briefly.
Q: What are the common side effects of prostate cancer treatment?
Dr. Weidhaas: Urinary side effects, also known as genitourinary (GU) toxicity, are the most common side effects for prostate cancer patients treated with either radiation or surgery. The urethra (your urinary tube) passes through the middle of the prostate, so it is affected by treatment. In surgery, they cut the urethra and sew it back together, which can cause incontinence (lack of control over urination). When radiation is used, the urethra will receive high doses of radiation. The urinary side effects after radiation are most commonly urinary urgency, incomplete emptying of the bladder, and frequency. You could also have scarring of the urethra where it is narrowed and you need to use a catheter because the urine won’t come out. Usually, these side effects are managed with medicines but sometimes surgical procedures are necessary to manage them.
Q: Are there different types of radiation toxicity?
Dr. Weidhaas: Yes, there are two types of toxicity from radiation. There’s toxicity people might experience during treatment or within the first couple of months afterward – that’s called acute toxicity. Usually, it will resolve on its own.
However, some patients are fine during or soon after radiation treatment, but nine months or a year after, they start developing urinary symptoms. That is called late toxicity, and it often does not go away.
Q: What is PROSTOX, and how does it work?
Dr. Weidhaas: We have developed two tests to help identify patients who are at higher risk of late urinary toxicity from prostate cancer radiation, based on a new understanding of genetics.
The tests look for a set of genetic biomarkers that can identify differences in people that predict a high risk of developing late urinary toxicity. The tests identify about a tenfold increased risk. One test is for SBRT and is called PROSTOX ultra, and the other test is for CFRT and is called PROSTOX CFRT.
Q: How does PROSTOX help patients and their healthcare providers make better decisions?
Dr. Weidhaas: Right now, if a patient is considering radiation, they are told they have about a 15% chance of developing late urinary toxicity if they get either SBRT or CFRT, and that is all the information we’ve had.
PROSTOX can tell a patient if they are at a low risk or high risk of developing late urinary toxicity. Someone who is low risk has about a 5% chance of developing late urinary toxicity and someone who is high risk has about a 75-80% chance of developing late urinary toxicity. So this is really helpful information for a patient and their doctor to help them decide on the safest treatment.
The great thing is that if a patient wants radiation, there are two PROSTOX tests, one for each of the main types of radiation. A patient can be high risk for the SBRT treatment, but low risk for the CFRT treatment, and vice versa. Only about 1-2% of people are at high risk for both types of treatments, meaning that 98% of people can safely get one of these forms of radiation. There are alternative treatment options for patients who can not safely receive radiation.
Q: What makes the PROSTOX test unique compared to other diagnostic tools or predictive tests?
Dr. Weidhaas: Currently, no other tests predict late radiation GU toxicity.
Q: How can giving patients access to PROSTOX shape the future of prostate cancer treatment?
Dr. Weidhaas: Currently, about half of prostate cancer patients get surgery and half get radiation. Many people who get surgery might not know radiation is an option and a safe treatment path for them. That’s why I think it’s important to empower these patients to have all of the necessary information to make the best treatment choices.
Q: What role does this type of genetic testing play in the future of oncology and personalized medicine?
Dr. Weidhaas: My hope has always been to empower patients and their physicians to make the best choices – that is the mission of MiraKind. That’s really how treatment should be — a personal decision with the most and best available information to help with making that decision.
PROSTOX is helping to personalize prostate cancer care, allowing patients and their doctors to choose the safest radiation treatment. You can access PROSTOX here.
If you wish to support MiraKind’s mission to spread awareness of, access to, and research into personalized cancer prevention and treatment. Make your tax-deductible donation today!
References
- “A SNP in a let-7 microRNA Complementary Site in the KRAS 3′ Untranslated Region Increases Non–Small Cell Lung Cancer Risk” https://aacrjournals.org/cancerres/article/68/20/8535/541399/A-SNP-in-a-let-7-microRNA-Complementary-Site-in
