Exploiting Human Microbiota-associated in Vivo Models for Mechanistic Studies to Understand the Benefits of Dietary Fibre Supplementation in Patients With Prostate Cancer

Prostate cancer is the commonest cancer in men and the fifth most common cause of cancer-related deaths globally. Increased prostate-specific antigen (PSA) screening and longer life expectancies in men have resulted in a substantial increase in the incidence and prevalence of prostate cancer in older men. Between 2021 and 2022, over 50,000 newly diagnosed cases of prostate cancer were reported in the UK, representing a 27% increase in incidence compared to 2019 and causing over 16,000 deaths.

Prostate cancer in its initial stages maybe asymptomatic and progresses slowly, meaning that some men do not need immediate active treatment but can be monitored on 'active surveillance'. Active surveillance was developed as an approach to addressing overtreatment; by delaying or preventing unnecessary definitive treatment, typically surgical removal of the prostate (radical prostatectomy, RP) or radical radiotherapy to the prostate (RT), and their related complications. It involves routine monitoring of PSA levels, medical imaging, digital rectal exams, and prostate biopsies and is recommended for prostate cancer patients with a low risk of developing aggressive tumours.

The process of active surveillance can be quite stressful for some patients and many of these patients are eager to do everything they can to slow the progression of their disease, including making lifestyle changes such as changing their diet and doing physical exercise.

Diet influences the diversity of the microbiota (archaea, bacteria, fungi and viruses) in the gastrointestinal tract. The gut microbiota play crucial functions in metabolic and regulatory processes that impact the body's immunity and disease development. One can increase the consumption of dietary fibre by providing supplements in powder or capsule form, where the dose administered can be controlled. When these dietary fibres are eaten, commensal colonic bacteria ferment them to produce metabolites, including short-chain fatty acids (SCFAs) which can have anti-tumour effects.

This study team and other researchers have reported the effect of the soluble dietary fibre inulin in delaying tumour growth in mice compared to low dietary fibre intake, in a range of tumour types (including bladder and colorectal cancers). Pectin has also been reported to have health benefits such as maintaining the intestinal barrier, improving physical bowel function and reducing glucose and cholesterol absorption. Apple pectin has also been shown to induce apoptosis in colorectal cancer cells.