Should C-reactive protein elevations be considered to postpone chemotherapy cure in lung cancer cases?

OBJECTİVE: Lung cancer patients often face infection, which is the majör cause of morbidity and mortality. It is difficult to distinguish a new infection in this patients because of the clinical, laboratory and radiological findings. When C-reactive protein (CRP) elevation is considered as an indicator of infection, it may cause disruption of chemotherapy courses and impairment of disease control in patients with lung cancer. Because the CRP value is generally high in these patients and other pathologies that may increase CRP can often accompany. It is necessary to know precisely whether the CRP elevation indicates an infection that prevents chemotherapy, and to decide whether or to postpone the chemotherapy cure at the scheduled time. In this study, it has been investigated in which cases the CRP elevation will be considered as an infection finding that prevents chemotherapy administration or not, and it is aimed to find a cut-off value that can predict the infection. METHOD: Patients with lung cancer and high CRP values between May 2018 and December 2019 in the Department of Chest Diseases, Faculty of Medicine, Karadeniz Technical University, were prospectively studied. Clinical features, laboratory and radiological findings of the patients were evaluated. The patients were divided into two groups as infectious and non-infectious with the final decision of the follow-up physician. A comparison was made between both groups in terms of clinical, laboratory and radiological features. The CRP cut-off value that could predict the infection was calculated. RESULTS: Of the 180 patients in the study, 171 (95%) were male and 9 (5%) were female, the mean age was 63.3±7.4. The mean CRP value of the patients was 4.5 mg/dl at the time of admission. With the decision of the physician, it was concluded that 23 patients (12.8%) had infection. The mean CRP value of 23 patients who were accepted as infectious by the physician's decision was 13.0 mg/dl, and 3.3 mg/dl for 157 patients who were considered non-infectious. The mean CRP value of patients accepted as infected was higher than patients who were not considered infected (p <0.0001). Procalcitonin, leukocyte count, PNL / Leukocyte ratio, sedimentation values were found to be higher in the infected group. The mean CRP at presentation and post-treatment CRP of 23 patients accepted as infected and given antibiotics were found to be 12.79 mg/dl, 5.4 mg/dl, respectively. The difference of 7.35 units was statistically significant (p <0.0001). Significant decrease in CRP level was found after treatment in patients who received antibiotherapy for infection. Cut-off values that could predict infection were determined in all patients and specific groups. The cut-off value for the admission CRP level was 6.74 mg/dl with 91.3% sensitivity, 86.6% specificity, 50% positive predictice value and 98.6% negative predictive value in predicting infection that would prevent chemotherapy in all patients (p <0.001). The cut-off value was 4.04 mg/dl with 73.6% sensitivity, 94.3% specificity, 63.6% positive predictive value and 96.4% negative predictive value for predicting the infection that would prevent chemotherapy in all patients (p <0.001). CONCLUSİON: In our study, cut-off values were found in patients who applied chemotherapy cure and had high CRP values, which could differantiate infection from other reasons that may increase CRP. With the use of the cut-off values found, unnecessary postponement of the chemotherapy treatment can be prevented by accepting non-infectious patients with high CRP levels as infected.