To Örebro University

Chronic inflammation has been implicated in the development of several types of cancer, and evidence from observational and animal studies suggests that it may play a role also in prostate carcinogenesis. Recent observations have brought Cutibacterium acnes (C. acnes) forward as a possible causative agent in pro-oncogenic prostatic inflammation. However, evidence also suggest that underlying immune characteristics contribute to prostate cancer risk. The overall aim of this thesis was to explore potential mechanisms underlying the proposed link between inflammation and prostate cancer, by evaluating associations between inflammatory conditions during early adulthood, circulating inflammation markers, and prostate cancer. Due to the suggested role of C. acnes in both diseases, we aimed to investigate whether acne vulgaris is a determinant of prostate cancer. Using prospectively collected data from Swedish national registers, we observed that presence of acne during early adulthood conferred an increased risk of prostate cancer later in life. Similarly, we found that appendicitis before late adolescence – a proposed marker of individual immune characteristics – to be positively associated with subsequent prostate cancer. We further evaluated whether prostatic C. acnes infection is linked with elevated systemic levels of IL6 and CXCL8, two inflammation markers previously associated with prostate cancer. No association was observed, however, potentially explained by the subclinical low-grade infection typically caused by C. acnes. Finally, we evaluated 52 circulating inflammation markers as determinants for prostate cancer in a population-based case-control study. In this hypothesis-generating study, we identified CX3CL1, CCL21, PDGF-BB, CCL11 and IL10 as candidate markers for evaluation in prospective studies. If confirmed, these markers may hint at targetable molecular pathways involved in prostate carcinogenesis.