Ventilation/perfusion relations in patients with small cell anaplastic carcinoma of the lung, obtaining complete remission during combination chemotherapy.

81mKr ventilation lung scans, 99mTc perfusion lung scans and lung function tests were performed in 25 patients with small cell lung cancer during combination chemotherapy in order to characterize the physiological changes in responding patients. After 3 months of chemotherapy 12 patients had obtained complete remission (CR), with total disappearance of all visible tumor tissue at the chest X-ray, 5 had obtained partial remission, 2 had progressive disease and 6 had died. Prior to treatment a mixed pattern of restrictive and obstructive lung function decrease was observed. The patients had a significant decrease in both ventilation and perfusion (P less than 0.01) of the affected lung and a ventilation perfusion mismatch was seen. Three months after initiation of treatment the patients who obtained CR had a statistical improvement (P less than 0.01) of TLC, VC and FEV in 1 sec, rendering them statistically inseparable from a healthy control group. The ventilation of the affected lung in patients obtaining CR increased statistically (P less than 0.01), but only a minor increase in perfusion (P less than 0.1) was seen so that the ventilation-perfusion ratio remained distorted. It is concluded that even though an increase of static and dynamic lung function parameters, including the ventilation of the affected lung, are seen in patients with small cell lung cancer obtaining complete remission during combination chemotherapy, a marked functional decrease of the perfusion and a ventilation-perfusion mismatch remain.