Imaging Prostate Cancer
Posted: Nov 01, 2018
POSTED: December 17, 2018
Professor Rob Newton is the Associate Dean of Medical and Exercise Sciences and the Co-Director of the Exercise Medicine Research Institute, School of Medical and Health Sciences at Edith Cowan University in Perth, Australia.
Dr. Newton offers exercise recommendations for men with prostate cancer.
Dr. Robert Newton: Definitely. One fellow in particular had never exercised since he was a young boy, was quite overweight, and had very low fitness. When diagnosed with prostate cancer his urologist told him, “Don’t worry about having cancer, because you are going to die of a heart attack long before your prostate causes you problems.” I worked with the dietician in our team to develop a very low caloric diet and a relatively high volume exercise program for him. He lost 21 kg of fat in eight weeks. The transformation in his health and fitness was phenomenal. His urologist could not believe the change and commented that the prostatectomy was much easier and more successful than he expected.
This, and many other experiences supporting men with prostate cancer, has convinced me of the massive difference that an appropriate exercise prescription can have for these patients. We can definitely improve their outcomes.
Dr. Newton: As yet, there is not definitive clinical trial evidence of the impact of exercise on prostate cancer progression. We are currently running a world first trial in men with localized disease specifically to address this question.
However, preclinical experiments involving prostate cancer cell lines have demonstrated up to 30% suppression of growth. There are now several animal studies demonstrating similar cancer suppression. What is more clearly supported by multiple human trials is that specific exercise reduces complications and side-effects of surgery and various treatments and may also actually enhance the effectiveness of radiation therapy and chemotherapy.
There is less evidence with regard to exercise improving tolerance of radiation therapy, however, there are strong theoretical mechanisms by which exercise performed immediately prior to a radiation therapy session may actually enhance the effectiveness of the radiation, resulting in greater cancer cell death. This occurs by increasing blood flow through the tumor, facilitating the oxygen enhancement effect of the radiation.
By far, the strongest evidence as to the benefit of exercise is for men on ADT for their prostate cancer. There are now many large randomized controlled trials clearly proving that exercise reduces the toxicities of ADT. In particular, exercise slows or prevents muscle and bone loss and limits the onset of metabolic diseases such as diabetes and cardiovascular disease, which are common side effects of ADT.
Dr. Newton: Ideally, men with prostate cancer would seek the assistance of a qualified exercise professional, such as a clinical exercise physiologist. These allied health professionals are university trained and have specific knowledge and skills in exercise assessment and prescription for people with chronic diseases like cancer. I do recommend that patients go through this process to ensure that they have an optimal exercise prescription that addresses the morbidities and risk of mortality in a prioritized strategy. This means designing an exercise prescription tailored for the individual and the problems that they are experiencing.
Dr. Newton: Unless there are other comorbidities and provided that the men are relatively healthy, then my recommendation would be for them to try and meet the American College of Sports Medicine guidelines for healthy older adults: 75 to 150 minutes per week of moderate to vigorous aerobic exercise and two or more resistance training sessions exercising all of the major muscle groups. This does not really need the input of a qualified exercise professional, but could be pursued under self-management or in a local fitness center.
Dr. Newton: Men on ADT may experience considerable toxicities, which impact their physical structure and function as well as greatly increase the risk of chronic diseases such as diabetes and cardiovascular disease. These men really need a tailored exercise prescription that targets the health issues causing them the greatest morbidity. For example, loss of muscle mass is a major problem for men on ADT. It requires a highly specific program of resistance training involving higher volume (or dosage) combined with a protein intake of at least 1.6 g per kilogram body weight per day. Maintaining muscle mass in these men is very important because it is a strong predictor of cancer recurrence and mortality.
Another ADT side-effect is bone loss which places the patient at considerable risk of skeletal fracture. In this instance, a highly specific exercise prescription incorporating resistance training and special impact loading consisting of skipping, jumping, and hopping is recommended as recent research has demonstrated that other forms of exercise have absolutely no benefit in terms of ameliorating the bone loss. However, such programs are highly advanced and must be closely monitored requiring supervision by a qualified exercise professional.
Dr. Newton: Post surgery, the patient will be considerably deconditioned in terms of muscle and strength loss and reduced cardiorespiratory fitness. They may also have some surgical complications, the most common of which is urinary incontinence. Exercise should be commenced as soon as possible after surgery to reduce further decline, albeit at a relatively modest dosage of aerobic and resistance training. As the patient recovers from surgery, exercise volume and intensity should be increased as tolerated. In particular, if urinary incontinence is experienced then targeted exercise prescription including pelvic floor exercises as well as exercises for the large muscle groups around the pelvis should be included. Just because a man has urinary incontinence, he should not avoid exercise and must perform resistance training even if he experiences some leakage. Resistance training has been demonstrated to enhance recovery of continence.
Dr. Newton: Patients should continue to exercise throughout the course of radiation therapy even when experiencing treatment-related fatigue. If fatigue is a major problem, than the volume of exercise should be reduced and the intensity increased with a greater emphasis placed on resistance training and a reduced volume in particular of aerobic exercise of low intensity. In our clinic, we provide a specific exercise program of 10 to 20 minutes incorporating aerobic exercise and resistance training of the muscles of the pelvic area (e.g. squat, lunge, step-up) advising the patient to complete this program immediately before they enter the room to receive the radiation therapy. As noted above, there is emerging evidence that this strategy may greatly increase the effectiveness of radiation therapy to destroy cancer cells.
Dr. Newton: Patients should exercise throughout the course of chemotherapy, however this should be auto-regulated. What this means is that the intensity and volume of exercise in a given session is adjusted up or down depending on how the patient feels on that particular day. The exercise program should be designed specifically to address key health issues facing the patient in a priority order.
Similar to radiation therapy, there is good evidence that performing a short exercise bout immediately before receiving chemotherapy may enhance its effectiveness by increasing blood flow through the tumor, thereby delivering more of the drug. It appears that there is a strong relationship between chemotherapy tolerance/side effects and the muscle mass of the patient. Patients with low muscle mass experience more chemotherapy side effects and are more likely to require a dose reduction. Receiving less than the plan dose of chemotherapy reduces overall effectiveness.
Dr. Newton: We are currently leading an international trial of highly targeted exercise in men with advanced prostate cancer, many of which are receiving the latest super anti-androgens such as Zytiga (abiraterone) and Xtandi (enzalutamide). The trial is in progress, but our initial results are that these men are tolerating the exercise program and reporting excellent improvements in quality of life and physical function. Until this and other trials in this patient population are completed, it is not known the degree of benefit of exercise in men on these drugs. Regardless, exercise confers considerable benefit to all patients in terms of both mental and physical health.
Dr. Newton: As a final note, it is absolutely critical that men with prostate cancer do some exercise on most if not every day of the week regardless of the stage of their disease and even when undergoing difficult treatments. The outdated recommendation of rest is now completely rejected. However, the exercise prescription must be tailored to the specific health issues of the individual patient, prioritizing those morbidities causing the greatest problems and risk of mortality.