A case control analysis of pattern and risk factors for pulmonary dysfunction amongst childhood cancer survivors: a single centre study from a low-middle income setting.

Pulmonary toxicity is one of the most common morbidities experienced by childhood cancer survivors (CCS). The aim of this study was to identify prevalence, pattern of dysfunction, and risk factors among CCS and compare with age and sex matched controls. Details of demographic and pulmonary-toxic treatment of CCS at least 2 years off-treatment were collected and a cross-sectional analysis of pulmonary function test (PFT) and risk factors was performed. Spirometry findings were categorized as normal, restrictive, or obstructive and diffusing capacity of carbon monoxide (DLCO) as normal or abnormal. PFT data of 192 CCS and 50 controls was analyzed. One or more abnormalities inspirometry or DLCO were observed among 112 (58.3%) CCS and 8 (16%) controls (p value <0.01). Abnormal PFT was more likely to be associated with older age at evaluation, longer follow-up, and use of chest-directed radiotherapy (p value 0.002, 0.02, 0.03). DLCO was the most common abnormality observed in 85 (44%) patients. Obstructive and restrictive patterns were observed in 66 (34.3%) and 42 (21.8%) survivors respectively. There was no correlation between any risk factor and specific pattern of pulmonary dysfunction. On univariate analysis age at evaluation >20 years, follow-up >10 years, cumulative bleomycin more than 120 mg/m², chest-directed radiotherapy, surgery, and female gender were found to be predictive for abnormal PFT. On multivariable analysis first four factors retained significance. High subclinical prevalence among CCS especially in older patients with longer follow-up mandates longitudinal follow-up to assess long-term pulmonary outcome and plan intervention strategies for this subset.