Exercise as it relates to Disease/Exercise effects on prostate cancer patients undergoing androgen deprivation therapy

Prostate Cancer
The prostate is part of the male reproductive system. The walnut sized organ is located below the bladder and in front of the bowel. Its primary function is to produce fluid to protect and enrich sperm. The development of prostate cancer (PCa) occurs when the abnormal growth of cells mutate and form a tumour within the prostate. Left untreated, the tumour can spread to other areas of the body, including lymph nodes and bone, and can be life-threatening.

There are several symptoms associated with PCa, often dismissed as being a natural consequence of ageing. See further readings for an indepth description of symptoms.

Prevalence
Prostate cancer has the highest level of incidence for men within Australian and New Zealand populations. Approximately 18,700 men are diagnosed each year, with an approximate 14.9% mortality rate (over a five year period) in Australian and New Zealand alone. PCa is the second leading cause of cancer related deaths among the male population. It is more common for PCa to impact men over 50 years of age. However younger individuals, with family history of PCa, have a greater risk of developing the cancer.

Androgens
Androgens are primarily produced in the form of testosterone by the Leydig cells in the testes. It circulates in the blood where it binds with albumin and sex-hormone-binding-globulin. When testosterone enters prostate cells, it get converted to dihydrotestosterone, enabling it to have a greater affinity with the androgen receptors (AR). The development of prostate cancer relies on AR for the growth of the cancerous cells to avoid apoptosis. As a result, standard therapy for PCa is to deprive the cancerous cells of the androgens, i.e. through androgen deprivation therapy.

Androgen Deprivation Therapy
Androgen deprivation therapy (ADT) is a widely utilised form of hormonal treatment for advanced prostate sufferers. ADT can be achieved through either surgical castration or medicinal administration of luteinizing hormone-releasing hormone (LH-RH). LH-RH acts through blocking the androgen receptors, suppressing growth of the cancerous cells. The main aim of ADT is to reduce the size of the tumor in the prostate, further increasing the survival rate by reducing the amount of testicular androgen production via LH-RH. Studies have identified ADT to adversely be associated with significant morbidities, including an increase in body mass index, increased fat deposition, muscle atrophy, reduced strength, decreased insulin sensitivity, osteoporosis, fatigue, depression and loss of sexual functioning. Many of these side effects may compromise a patient’s quality of life (QOL), which can impair psychological wellbeing of the individual.

Exercise: An Intervention
Pharmaceutical intervention is expensive and does not provide an intervention to improve physical functioning or quality of life. Research has shown that men receiving ADT should undertake progressive resistance and aerobic training to alleviate the potential side effects of the treatment. Exercise as an intervention aims to do the following:

Resistance Training
Initially, resistance exercises should incorporate training machines (to provide concentric muscle contractions). Exercises should altered as the individual progresses, incorporating an adequate warm up and warm down and general flexibility exercises.

Aerobic Training
Cardiovascular training should also be incorporated within the exercise program. Initial aerobic exercises should be completed at a low intensity, increasing in intensity as the weeks progress.
 * Exercises: walking, cycling, jogging, or swimming.
 * Duration: 15 minutes (initially), and up to 45-60 minutes.
 * Intensity: 50-60% maximum effort, increasing to 75% maximum effort. Monitoring rate of perceived exertion and heart rate.