11 September 2020
If you’ve been diagnosed with prostate cancer, your overall health and fitness can impact your treatment options, as well as influencing how you physically recover from surgery and other types of therapy. Maintaining a healthy weight is key, a point backed up by new Australian research.
In a study of 43 overweight or obese patients aged 47 to 80 years old, researchers found that a low-calorie diet and exercise program before robotic assisted radical prostatectomy helped to reduce fat mass and blood pressure, with potential benefits for surgical outcomes.
Body weight risks and prostate cancer surgery
Surgical options for prostate cancer include open radical prostatectomy, laparoscopic radical prostatectomy, and robotic-assisted radical prostatectomy, and each approach has risks. In an open radical prostatectomy, surgeons make an incision of about 10cm in the lower abdomen, whereas laparoscopic radical prostatectomy involves small incisions and guidance by camera, and robotic-assisted radical prostatectomy uses a laparoscopic technique where surgical tools are guided by a computer.
Overweight and obese patients may require more time on the operating table and face a higher risk of excess blood loss, in addition to complications from airway pressure, due to a surgical position that elevates the feet. A patient’s weight can therefore create risks for the patient, as well as risks which can compromise the success of the surgical method itself.
In the days after surgery, overweight or obesity can contribute to poorer urinary and erectile function, higher chances of infection, and a greater likelihood that the cancer cells extend to the edge of the excised tissue, an occurrence known as positive surgical margins. Of concern, evidence has found a possible association between obesity and an increased likelihood of aggressive prostate cancer and prostate cancer-related death, rising PSA levels, less time before emergence of castrate resistance, and incidence of other conditions such as cardio-vascular disease.
Given the relative risks and possibility of poorer outcomes, body weight is therefore an important focus of discussion between clinicians and patients when making treatment decisions, with a desirable goal of weight loss prior to surgery for patients affected by overweight and obesity.
Lifestyle and prostate cancer treatment
Evidence suggests about 1 in 3 men with prostate cancer are likely to make positive lifestyle adjustments after their diagnosis, whereby more frequent contact with a health care team immediately after diagnosis can support a focus on guided weight loss activity ahead of surgery and other treatment. Under medical supervision, weight loss treatment plans typically involve monitoring of fat and lean mass and other measures of overall health and fitness.
Everyone has a different ‘healthy weight’, and there are a number of ways to measure it, including body mass index (BMI) and waist circumference. For more information about understanding your ideal body weight, check out the BMI calculator and other tools on the Department of Health website: http://healthyweight.health.gov.au/wps/portal/Home/get-started/are-you-a-healthy-weight/.
Losing weight safely is vitally important, whereby rapid weight loss and fad diets can cause a drop in lean body mass, which may impact physical function and overall health.
Prior to this Australian study, just two randomised controlled trials had investigated the effect and effectiveness of weight loss before radical prostatectomy using diet and exercise, with limitations in approach leading to inconsistent and inconclusive results.
About the research
A team of researchers from Western Australia used dual-energy x-ray absorptiometry (DXA) to precisely measure fat reduction and body composition in an initial and final consultation prior to each patient’s robotic-assisted radical prostatectomy (RARP). The study recruited 43 study men aged between 47 and 80 years old who attended a urology clinic in Perth, Western Australia over the two-year period from 2016 to 2018.
All patients took part in a supervised weight loss program designed by accredited allied health professionals, either dietitians or physiologists. Patients with a waist circumference over 94cm were invited to join.
The study was delivered collaboratively and involved the referring urology practice and an allied health clinic, with patients asked to attend a weekly appointment to achieve safe but rapid weight loss before surgery, with an objective to reduce fat mass, maintain lean mass, and observe standards of care concerning physical activity and nutritional intake. Each participant attended up to 12 appointments, depending on surgery dates, individual commitment, and weight loss goal attainment.
Of note, the clinical protocol required any smokers in the study to quit smoking, and compliance with the program was closely overseen and encouraged, with weekly weigh-ins and behavioural coaching to help overcome barriers to success and promote lasting change towards adoption of healthy lifestyle behaviours.
Patients were given prescriptions for exercise, including 90 minutes of moderate intensity cardio exercise each day at 60-80% of their age-based maximum heart rate. Exercises were carefully selected to guard against injury and optimise energy expenditure. Weight training wasn’t part of the program, although patients who already took part in regular resistance training were permitted to continue it throughout the study period prior to their surgery. All were given the choice of access to a gym facility under supervision of an Accredited Exercise Physiologist, or the option to exercise independently at home or outdoors.
A low-calorie diet up to about 4200 kilojoules per day was devised for each patient, guided by an Accredited Practising Dietitian. This included meal-replacement foods and drinks, at least two cups of low starch veggies, appropriate fluid intake, and a healthy amount of daily protein:
- One meal replacement shake, bar, or soup at each of three main meals throughout the day.
- Two cups of low starch vegetables or salad (low starch vegetables have less than 4 grams of carbohydrate per 100 grams).
- Between 1 and 1.07 grams of protein per kilo of body weight per day.
- Optimised fluid intake calculated on individual body weight.
Additional low-calorie foods and drinks were permitted, such as miso soup, sugar free lollies, artificial sweeteners, tea and coffee with minimal milk, and diet drinks. Fruit juice, alcohol, and sugar-sweetened beverages were strongly discouraged.
The median study period was 29 days, with a median of five nutrition appointments, and over 80% of all patients attending scheduled appointments.
Patients experienced significant decreases in fat mass, percentage body fat, trunk fat mass, visceral fat, lean mass, and limb muscle mass over the study period, as measured by DXA scans.
A majority (68.5%) of the loss in fat mass was from loss in trunk fat mass. All participants reported a total reduction in fat mass and trunk fat mass and five patients (11.6%) experienced an increase in lean mass and limb muscle mass.
Those with higher body weight at the start of the study had greater loss of weight, limb muscle mass, and lean mass. Of note, age was not associated with baseline body composition scores or change in composition over the study period.
Importantly, total body weight, BMI, waist circumference, and diastolic blood pressure all declined during the study and those who stayed on the program longer and attended more appointments with their dietician enjoyed greater overall weight loss.
Post-RARP outcomes were also measured, with the finding that patients who had a higher body weight had a higher number of adverse effects, which commonly included urinary incontinence (67.4%) and erectile dysfunction (32.6%), while around 1 in 10 experienced lymphedema (11.6%). No association was found between adverse effects of surgery and age or changes in fat mass and lean mass. While minor impacts of the dietary intervention were observed, such as hunger, headaches, and changes in bowel function, no major adverse events were caused by the dietary program or exercise prescriptions.
According to study authors, this Australian research was the first of its kind to assess a weight loss program offered as a standard care protocol for overweight and obese patients before robotic-assisted radical prostatectomy.
In a discussion of the results, the researchers emphasise the importance of four findings:
- A significant reduction in total body mass and fat mass.
- Reduced incidence of adverse outcomes from surgery with lower absolute fat mass.
- The observation that reduced fat mass was accompanied by decreased lean mass.
- Healthier blood pressure as a result of the program.
In particular, the researchers point out the benefit of significantly lower fat mass in the abdominal region and surgery area, which lowers the risks of complications during surgery. Participants achieved a 16.3% reduction in total fat mass, with an average loss of about five kilograms, and most of this was visceral fat in the trunk area, for an average eight-centimetre decrease in waist circumference. These results compare favourably to other studies, with roughly double the weight loss achieved through more severe caloric restriction and more exercise. However, the researchers do highlight the findings of one specific previous study as a matter of caution, where a marker of tumour cell proliferation appeared to increase in association with a weight loss intervention. The reasons for any link were not explained and require further investigation.
The loss of lean mass, on average about 2.5 kilograms for each patient, representing 32% of all weight loss, was identified as a concern by the researchers, given the link between loss of lean mass and challenges with longer-term weight control, increased bed nights spent in hospital, heightened risk of infections, and complications after surgery. However, the study authors suggest the health benefits of the overall weight loss outweigh the risks of this reduction in lean mass. The researchers also noted the potential for an increase in confidence owing to weight loss achieved, which could provide a potential motivator for participants to continue with activity towards a healthy weight throughout the life-course.
Likewise, clinically significant improvements in blood pressure and relative risks of heart disease were achieved, and these were found to be equivalent to the benefits of being medicated for blood pressure. This finding was especially relevant because blood pressure is critical during surgery, with an additional bonus that on a large scale, the reduced costs of blood pressure medication could help to cater for the costs of supervised weight loss programs as standard of care.
Consistent with all peer-reviewed medical and scientific research, the study also identified several broad limitations, chief among them the absence of a control group by which to make comparisons. Furthermore, the investigation’s emphasis on leveraging a large energy deficit to achieve fat loss was also considered a weakness, particularly in relationship to the unintentional loss of healthy lean mass. The researchers suggest that future studies consider incorporating a resistance training intervention to test whether fat mass can rapidly be reduced while retaining, and possibly even building, healthy muscle.
This research provides sound support for the idea that lifestyle medicine, such as diet and exercise prescriptions, can improve prostate cancer outcomes and overall health, reducing risks of surgical complications and enhancing recovery. We expect this important finding will lead to ongoing research in this area, towards the implementation of healthy lifestyle interventions in routine treatment for prostate cancer, through uptake of tailored approaches which can be delivered by experts in the field.
For our part, PCFA will continue to support Australian men and families with improving their overall health and survivorship prospects. To find out more about current work in this area, check out The Long Run and challenge yourself to walk, run, or wheel 72km for the one you love this September.
Go to https://www.thelongrun.org.au/
or call on us anytime for support via 1800 22 00 99.
To read the full research paper, click on the link below: