Experts describe new treatments for advanced & metastatic prostate cancer
In recent years, there’s been enormous growth in the availability of treatments for advanced and metastatic prostate cancer, from newer forms of hormone and radiopharmaceutical therapy to radiation therapy.
Medical oncologist Dr. Austin Poole and radiation oncologists Drs. Dario Pasalic, MD, and Patrick Richard, MD, MPH — all with Rocky Mountain Cancer Centers-Boulder (RMCC-Boulder) — co-presented a free health lecture on the latest treatments for advanced and metastatic prostate cancer.
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Watch "What's new in treating advanced and metastatic prostate cancer"
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Approaching prostate cancer care as a team
BCH has multidisciplinary cancer care teams, consisting of a range of health professionals who treat cancers. This comprehensive team approach, which is endorsed by the American Society of Clinical Oncology as a “Best Cancer Practice,” can improve quality of care and health outcomes because all the experts are involved in deciding the optimal treatment option.
Discussing one prostate cancer patient at a time, the oncology, urology, radiology and pathology team members share their opinions and then, by consensus, determine which care option is in the patient’s best interest.
“We're very proud at RMCC-Boulder and BCH of our multidisciplinary team, which has become critically important as we assess treatment options for patients with prostate cancer. Our patients deserve dedicated time and attention given to each of their unique cases,” said Dr. Richard as he kicked off the lecture.
He added, “Our bi-monthly cancer conference allows each prostate cancer expert to give undivided attention to each patient and develop unbiased treatment options that focus on efficacy, safety and quality of life.”
Risk stratification
Dr. Richard said one of the most important things to consider when making a care recommendation is the stage and grade of your cancer (risk stratification).
“Historically we've used the results of a Gleason score, a Prostate-Specific Antigen (PSA) test and/or a prostate exam to come up with the clinical risk. We also now use magnetic resonance imaging (MRI), positron emission tomography (PET) molecular imaging with prostate-specific membrane antigen (PSMA), and Decipher genomic testing, which are all very recent advances to better understand prostate cancer activity and biology,” he said.
The lecture focused on the following groups:
High-risk group - Prostate cancers in this group have grown outside the capsule of the prostate gland, the biopsy shows a Grade Group of 4 or 5 (Gleason score 8 to 10) or have a PSA level of more than 20.
Very-high-risk group – Prostate cancers in this group have spread to the seminal vesicles or other nearby tissues, the biopsy shows areas with a primary Gleason 5 pattern, or there are multiple high-risk group features.
Metastatic prostate cancer - Cancer that has spread beyond the prostate gland and found in other tissues and organs such as lymph nodes, bones, liver, lungs and brain to name a few.
Radiation therapy options for advanced prostate cancer
Next, Dr. Pasalic discussed radiation therapy for those with high-risk, very-high-risk or metastatic prostate cancer.
“Just because your PSMA PET scan doesn't show any metastatic disease, it doesn't mean that you're not at risk of developing distant metastatic disease,” said Dr. Pasalic. “There can be a milieu of microscopic cells that are already present and in such a low volume that we cannot visualize them very well through PSMA PET scan or MRI or bone scan. That risk is still there and needs to be addressed with appropriate treatment.”
He added, “This is why we will often combine local and regional therapy, such as radiation and surgery, with hormone therapy,” said Dr. Pasalic.
He then reviewed three main types of radiation therapy used for high-risk or very-high-risk prostate cancer:
External beam radiation therapy (EBRT) - EBRT, beams of radiation are focused on the prostate gland from a machine outside the body. This type of radiation can be used to cure prostate cancer or to help relieve symptoms, such as bone pain, if the cancer has spread outside of the prostate gland.
“During your normal course of EBRT, we deliver a higher dose to the region of the tumor but then give a lower dose to the surrounding tissue," Dr. Pasalic stated. "The idea is you can selectively boost parts of the prostate gland, while protecting other critical structures. This has demonstrated very good biochemical control with limited toxicity, thereby offering an alternative to brachytherapy without the associated side effects.”
He added, “Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are the most common types of external beam radiation therapy for prostate cancer. They use advanced hardware and software to ensure a conformal radiation plan — that is, treatment delivered at a higher dose of radiation to the cancer without causing much damage to surrounding tissues — in a timely and effective manner.”Brachytherapy (internal radiation) – Brachytherapy, also known as low dose-rate permanent seed implantation or high dose-rate catheter implantation, uses small radioactive pellets, each about the size of a grain of rice, or catheters. These pellets or catheters are placed directly into your prostate gland to deliver an additional, higher dose of radiation following EBRT.
“Brachytherapy is a well-studied treatment option but can often result in higher rates of side effects. Outside of brachytherapy, the most promising area of investigation in escalating dose to the prostate is in what we call a focal lesion ablative microboost or FLAME,” said Dr. Pasalic.Radiopharmaceuticals - These are intravenous injections of radiation particles that target cancer cells to treat metastatic prostate cancer. These medications typically have radioactive compounds linked to a targeting molecule, thereby allowing the radioactive compound to be absorbed into a cancer cell while sparing normal cells. Radiopharmaceuticals can be used in combination with EBRT.
Towards the end of his portion of the lecture, Dr. Pasalic added, “This is a very exciting time for radiation oncologists, as we try to figure out how we can use technology to give patients the best possible outcomes, while minimizing side effects and improving your quality of life.”
Treatments for metastatic prostate cancer
Dr. Poole then discussed treatments for two broad categories of metastatic prostate cancer:
Metastatic Hormone-Sensitive Prostate Cancer (mHSPC)
Metastatic Castration-Resistant Prostate Cancer (mCRPC)
Metastatic Hormone-Sensitive Prostate Cancer (mHSPC)
Metastatic hormone-sensitive prostate cancer (mHSPC) occurs when the cancer has spread past the prostate into the body. Male sex hormones can be blocked or stopped to slow cancer growth.
“Although there is currently no cure for mHSPC, the goal of treatment is to help slow the progression of your prostate cancer,” Dr. Poole said.
Options may be:
Hormone Therapy - Hormone blocker therapy is any treatment that lowers a man’s androgen levels. It is also called androgen deprivation therapy, or ADT. This type of treatment for mHSPC helps block production of male sex hormones as a way to slow cancer growth.
Dr. Poole said, “Today, ADT is the backbone of all systemic therapies of mHSPC. It is continued, even in case of a change in therapy.”
ADT can be combined with other therapies, such as:
Androgen pathway-directed therapy (such as abiraterone acetate plus prednisone, apalutamide, enzalutamide)
Chemotherapy (docetaxel)
Stereotactic radiation therapy (to help control prostate cancer in the prostate gland itself or once it has spread to other parts of the body such as the lymph nodes, lungs, bone, liver and brain)
Metastatic Castration-Resistant Prostate Cancer (mCRPC)
“With Metastatic Castration-Resistant Prostate Cancer (mCRPC), hormone therapy no longer stops cancer growth. The cancer no longer completely responds to treatments that lower testosterone. It shows signs of growth, like a rising PSA, even with low levels of testosterone,” Dr. Poole said.
He added, “The main goal for treating mCRPC is to control symptoms and slow progress. Even though ADT or hormone therapy may no longer work completely to stop prostate cancer from growing, most men with mCRPC remain on ADT because some prostate cancer cells will continue to respond to it.”
For mCRPC, other treatments may be added, such as:
Chemotherapy (docetaxel and cabazitaxel). These chemotherapies are drugs that may help extend how long men can live with mCRPC. Cabazitaxel is given with the steroid prednisone and is an option when docetaxel doesn’t help.
Immunotherapy - This treatment takes your immune cells and helps them fight cancer cells. “Unfortunately, immunotherapy is somewhat ineffective for metastatic cancer. However, we can improve the response of immune therapy in what appears the addition of a medication called cabozantinib. Including this medication seems to have some benefits.”
Second-line hormone therapies such as abiraterone and enzalutamide. These target male hormones in different ways than first-line ADT.
Radiopharmaceuticals - This is treatment is used to attack cancer cells in bones. (See description in previous section.)
Clinical trials are research studies to test new treatments or learn how to use existing treatments better, or in combination.
Gene therapy includes medication options that may be helpful for some patients whose tumors show certain genetic mutations. These mutations are found through a process called genomic sequencing of the cancer. “Poly-ADP ribose polymerase inhibitors, or PARPi, are an emerging therapeutic option for patients with mCRPC and with a BRAC mutation. The importance of identifying a BRAC mutation is that we can now target that mutation with PARP Inhibitors. These are oral medications,” said Dr. Poole.
“During your care, it is of great value to tell your health care provider about your symptoms and feelings. Cancer can be hard to deal with, especially metastatic cancer. Your health care team is available to help you,” Dr. Poole emphasized.
If you'd like to schedule an appointment with medical oncologist Austin Poole, MD, of Rocky Mountain Cancer Centers, call 303.385.2000. To schedule an appointment with radiation oncologists Dario Pasalic, MD, or Patrick Richard, MD, MPH, also with Rocky Mountain Cancer Centers, call 303.385.2068.