Polymerase chain reaction positivity of Pneumocystis jirovecii during primary lung cancer treatment.

Objective: When treating lung cancer, pneumocystic pneumonia is a life-threatening complication seen during chemotherapy. Polymerase chain reaction is used to detect its cause, Pneumocystis jirovecii, but polymerase chain reaction positives without pneumocystic pneumonia are sometimes seen. The purpose of this study was to assess the frequency of pneumocystic pneumonia during cancer treatment.

Methods: Fifty induced sputum specimens and 4 bronchoalveolar lavage specimens collected from 50 patients with acute respiratory symptoms during anticancer therapy were retrospectively studied after classifying the patients into lung cancer (n = 29) and solid tumor (n = 21) groups. All of the patients in both groups had an interstitial shadow suspected of being pneumocystic pneumonia, and all had polymerase chain reaction tests.

Results: Eleven of the 54 specimens were polymerase chain reaction positive, and 1 patient was clinically diagnosed with pneumocystic pneumonia. The incidence of polymerase chain reaction positivity in the lung cancer group was significantly higher than in the solid tumor group (31 vs. 5%; P = 0.03), and the incidence of subclinical pneumocystic pneumonia (29 vs. 5%; P = 0.059) also tended to be higher in that group. There were no significant biochemical differences between the two groups, irrespective of the polymerase chain reaction results. Among polymerase chain reaction-positive patients in the lung cancer group, the cumulative dose of corticosteroid administration tended to be higher than among the polymerase chain reaction-negative patients (P = 0.09). Following the polymerase chain reaction tests, nearly all polymerase chain reaction-positive patients without pneumocystic pneumonia received antipneumocystic agents, and none developed pneumocystic pneumonia.

Conclusions: Our findings suggest polymerase chain reaction positivity for P. jirovecii will be detected in a fraction of lung cancer patients. Although it is difficult to predict the need for administration of pneumocystic pneumonia treatment to subclinical pneumocystic pneumonia based on polymerase chain reaction and biochemical results, polymerase chain reaction-positive patients should be followed-up with antipneumocystic agents to ensure they are not at an early stage of pneumocystic pneumonia.