Several lifestyle factors have been discussed as potential parameters with an impact on prostate cancer risk and prognosis. These have largely been developed based on two robust and impactful recent systematic reviews by the ESOU1,2
There is strong evidence that smoking is associated with aggressive tumor features and worse cancer-related outcome, which seems to be maintained for 10 yr after smoking cessation1. CSM is enhanced by 24-30% in heavy smokers with a consistent and dose-dependent association in smokers and ex-smokers. The hypothesis for these results is that there is less PSA-screening (1.95-fold higher rate of screening among non-smokers) and biopsies performed among smokers (36% reduced the chance of a second biopsy). Furthermore, it has been suggested that PSA values are 8-12% lower in smokers than non-smokers. From a genetics perspective, smokers have inhibition of the immune system and increased chronic inflammation, all of which may associate with adverse outcomes.
Less convincing and limited evidence exists for the association of sexual activity with prostate cancer risk1. A reduced prostate cancer diagnosis has been suggested for men with increased ejaculatory frequency, in addition to decreased risk with increasing number of sexual partners. It is generally accepted that patients with sexually transmitted diseases have increased odds for prostate cancer, with the strongest (yet still weak evidence) for HPV infection. The literature surrounding vasectomy increasing risk of prostate cancer diagnosis has historically been inconclusive, however, a recent systematic review and meta-analysis found no association between vasectomy and high-grade, advanced-stage, or fatal prostate cancer3.
The findings related to physical activity and prostate cancer support the inference that exercise might be a useful factor in the prevention of prostate and tumor progression, while it is not fully evident under which specific conditions physical activity may be protective against disease development 1. The hypothesis for this perceived benefit is a reduction of chronic inflammation, IGF-1 and insulin levels, reduced oxidative stress, as well as modulation/stimulation of the immune system.
The role of obesity and risk of prostate cancer and the effect on outcomes has been a widely debated topic. Body mass index in middle age may be associated with a modestly decreased risk of prostate cancer, however, according to Dr. Brookman-May, there is no evidence of an effect on either biochemical recurrence or lethal prostate cancer. Assessing waste circumference, there is more conflicting evidence: increased waist circumference is associated with an increased risk of overall and high-grade cancer, but lower risk of low-grade cancer.
Dr. Brookman-May notes that the obesity literature is plagued by several limitations:
- Very heterogeneous evidence
- Highly variable definitions and length of follow-up
- Potential PSA hemodilution in obese men cannot be ruled out
- Potential selection bias and confounders eg. medication, comorbidity
- There is conflicting evidence concerning the association of smoking and prostate cancer risk, but robust evidence for an association of smoking with aggressive tumor characteristics
- There is robust evidence for a dose-dependent association of smoking with CSM
- There is limited evidence regarding a potential role of sexual activity and prostate cancer risk
- Regarding vasectomy, there is no (weak?) association with prostate cancer risk and no significant association with high-risk or lethal prostate cancer
- There is relatively reliable evidence that physical activity reduces prostate cancer risk, however, it is not yet defined under which specific conditions sports is protective (intensity, timing, type)
- There is low adherence to physical activity programs and long-term training programs are needed
Presented by: Sabine D. Brookman-May, MD, Associate Professor Urology, Ludwig Maximilian University of Munich, Germany, Director Clinical Research Oncology
Janssen Research & Development, Los Angeles, California, USA
Written by: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, Twitter: @zklaassen_md, at the 16th Meeting of the European Section of Oncological Urology, #ESOU19, January 18-20, 2019, Prague, Czech Republic
- Brookman-May SD, Campi R, Henriquez JDS, et al. Latest Evidence on the Impact of Smoking, Sports, and Sexual Activity as Modifiable Lifestyle Risk Factors for Prostate Cancer Incidence, Recurrence, and Progression: A Systematic Review of the Literature by the European Association of Urology Section of Oncological Urology (ESOU). Eur Urol Focus 2018 Mar 22 [Epub ahead of print].
- Campi R, Brookman-May SD, Subiela-Henriquez JD, et al. Impact of Metabolic Diseases, Drugs, and Dietary Factors on Prostate Cancer Risk, Recurrence, and Survival: A Systematic Review by the European Association of Urology Section of Oncological Urology. Eur Urol Focus 2018 Apr 13 [Epub ahead of print].
- Bhindi B, Wallis CJD, Nayan M, et al. The Association between vasectomy and prostate cancer: A systematic review and meta-analysis. JAMA Intern Med 2017 Sep 1;177(9)1273-1286.