Identification of low oxygen tolerating bacteria in prostate secretions of cancer patients: aetiological and therapeutic relevance

Abstract Background The sun-sensitive microaerophilic organism Propionibacterium acnes shows linkage with prostate cancer. That circumcision reduces risk of this cancer further supports a role for anaerobes since circumcision reduces the number of anaerobes on the glans penis. A 1988 study linked anaerobes with prostate cancer but considered them to be opportunists in a necrotic tumour. Rediscovering this research led us to revisit the previous hypothesis suggesting that decades of a similar process to that linking Helicobacter pylori (also microaerophilic) to stomach cancer might also be relevant in prostate cancer; and justified this feasibility study to seek evidence to support this hypothesis. Methods Two groups of patients were studied: patients with prostate cancer from Barts prostate clinic (active surveillance, n=18) and new referrals with urinary symptoms for investigation through Newham General Hospital (n=21). Urine samples from post-massage examinations were screened with matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) for identification of bacteria grown under anaerobic conditions. Ten preoperative urine samples investigated for non-urological conditions were controls. Findings Anaerobic organisms were identified in eight (41%) of 18 patients in the active surveillance group, nine (43%) of 21 in the new referral group, and none of ten control samples. In a post-hoc analysis, anaerobes were associated with raised prostate-specific antigen (PSA) (1 [9%] of 11 men with PSA Interpretation The numbers of prostate cancers in this series and in similar series in the literature are small (n=27) but the frequency of anaerobes in a comparison with literature control urine samples cultured for anaerobes (n=551) was significantly different (odds ratio 17·8, 95% CI 7·6–42·0). Clearly this needs further investigation in better defined patient and control series. Over several decades anaerobes could be of aetiological significance in prostate cancer and exacerbated by repeated episodes of vitamin D deficiency, thereby explaining linkage with long-term sun exposure but not spot vitamin D concentrations. Success with bacterial vaccines for women with recurrent cystitis suggests potential new approaches to prevent prostate cancer and potentially also cervical cancer in women infected with HPV, given evidence that bacterial vaginosis also involving anaerobes is a known cofactor of cervical cancer. Funding MW received a grant from Barts and The London Charity for purchase of MALDI-TOF equipment (grant reference number 486/1193).