Pneumocystis jiroveci pneumonia and colonization in patients with advanced lung cancer

Pneumocystis jiroveci pneumonia (PCP) has long been recognized as a cause of mortality in immuno-compromised populations, including those with advanced lung cancer. Although Pneumocystis colonization has only recently been described due to the development of more sensitive molecular techniques, including polymerase chain reaction (PCR), it is unknown whether Pneumocystis colonization leads to the development of PCP. In the present study, we aimed to determine the prevalence of Pneumocystis colonization in advanced lung cancer patients. Furthermore, the association between PCP and Pneumocystis colonization was also investigated. Advanced lung cancer patients with no indication of PCP were evaluated to determine the prevalence of Pneumocystis colonization. We analyzed their oral wash (OW) samples and retrospectively evaluated advanced lung cancer patients with PCP by analyzing their sections of formalin-fixed, paraffin-embedded lung tissues obtained following a diagnosis of lung cancer. Pneumocystis colonization was determined by a PCR test for Pneumocystis jiroveci (P. jiroveci). No P. jiroveci was detected by PCR in the OW samples of 47 advanced lung cancer patients with no indication of PCP, or in the lung tissues of four advanced lung cancer patients with PCP. These results indicate that PCP is not associated with Pneumocystis colonization in advanced lung cancer patients, although this study is limited since this was a cross-sectional and retrospective study.