Comparisons of the growth in tissue culture of primary and metastatic melanoma.

Tissue culture studies using monolayer cultures or semi-solid cultures under hypoxic or ambient oxygen conditions were carried out in 86 primary and 241 metastatic human melanomas. The frequencies with which growth occurred were similar for primary and metastatic tumours for each of the culture systems. In tumours which grew in hypoxic semi-solid culture, however, the plating efficiency (numbers of colonies per 5 X 10(5) cells plated) was significantly higher (26.1 +/- 2.8) for metastatic melanomas than for primaries (11.9 +/- 1.4). Paired comparisons of the growth of individual tumours in hypoxic cultures with growth in ambient oxygen cultures confirmed earlier observations that growth was enhanced by hypoxia due to recruitment of additional colony-forming cells. The numbers of cells recruited under hypoxic conditions were significantly greater for metastatic tumours than for primaries.