Summary of pathobiologic presentations.

T he ressmlts of a large rmumnber of investigations on the pathohiologv of smnall cell carcinoma (SCLC) were presented during this meeting. It is dif cult to even attempt to summarize adequately and fairly these presentations. Umidoubtedly, I will do this inadequately in sonic instances, and I wish to apologize to those investigators whom I unintentionally slight or whose work I may misrepresent. Unforttmnately some reports were qLiite preliminary with relatively small groups evaluated. Such presentations costtribute little to our understanding and may be misinterpreted or misleading. The biologic studies presented were quite diverse, but many of the papers can be placed into a few major categories, and I will discuss these groups together. An important area of study continues to he growth factors and growth factor receptors. As more studies are completed, this appears to become a progressively more complex problem. There were several reports on gastrin-releasing peptide (GRP), although interest in this peptide as a clinically significant growth factor seems to be waning. It was reported that intracellular and secreted GRP was extremely variable in cell cultures, varying from 10to 100-fold. Of particular interest, it was pointed out that extracellular levels which normally occur in culture were much lower than concentrations used in experiments which demonstrated a growth stimulation effect of GRP Antibodies to bomnbesin (BN) had no effect on proliferation in 1 study of cultured cells at low and high densit which was interpreted to indicate that SCLC lines have self-stimulating factors other than GRP. One ssmch other autocrmne growth factor seems to be