Gallium scintigraphy in small cell lung cancer.

We have undertaken gallium imaging studies in 49 patients with histologically proven small cell lung cancer. Tracer uptake in the primary tumour was seen in 98% of cases. Twenty five patients underwent repeat scanning after induction chemotherapy and a correlation was demonstrated between conventional parameters of response and gallium scan changes (P less than 0.01). There was no correlation between initial gallium activity and subsequent chemoresponse (which was evaluated in 32 patients) or survival (measured in 42 patients). Ten patients who had shown a complete response to induction treatment were followed up with gallium scans repeated at three monthly intervals. Such longitudinal studies were particularly helpful in excluding tumour activity when the appearance of the chest radiographs were difficult to interpret.