Lung cancer is the world's most common neoplasm and its incidence is rising. Lung cancer has the highest mortality rates of all cancers. Pulmonary infections, especially pneumonia, frequently complicate the course of lung cancer and are often the ultimate cause of death.~It has been suggested that bronchial colonization plays a key role in the establishment of pulmonary infections in patients with lung cancer, and thus clearly influences the therapeutic management and probably the prognosis of cancer.~In such patients, colonization may arise following local bronchial impairment, e.g. stenosis or impaired mucociliary clearance, or be caused by more general abnormalities, including immunosuppression, malnutrition, smoking, chronic obstructive pulmonary disease (COPD) and chemotherapy. Studies indicate that bronchial colonization can be demonstrated in 48.1% of patients with lung cancer and may be caused by potential pathogenic microorganisms (PPMs), mainly Haemophilus influenzae, Streptococcus pneumoniae and Staphylococcus aureus. Other potential microbial agents, such as mycobacteria and fungi, have not been investigated systematically However, there is a wide variation in the microbial profile reported from the previous studies; some of which reporting predominance of Gram-positive organisms- streptococcus pneumoniae in particular, while more recent studies reported predominance of Gram-negative organisms, which may indicate a shift in the spectrum of organism colonizing bronchial tree of lung cancer patients in parallel to the increased trends of antibiotic exposures, something this study will re-examine. Moreover, given the paucity of literature highlighting the potential predictors of colonization in such patients, overlooking data on radiological findings in lung cancer patients and underreporting the impact of comorbidities, this study aims to further explore a wider array of potential demographic, clinical, radiological and histological determinants.
Primary Aim:~-To determine the prevalence and pattern of bronchial colonization in patients presenting with lung cancer at the time of diagnosis~Secondary Aim:~-To assess the potential demographic, clinical, radiological and histological predictors of colonization in patients with lung cancer