The influence of site of metastasis on tumour growth and response to chemotherapy.

Drug screening trials and general treatment of solid tumours in advanced cancer patients have been concerned only with the site of primary origin, regardless of where metastases might have seeded. Since the environment for tumour growth can differ appreciably at various anatomical sites, an investigation was undertaken to determine the effect of metastatic site on response to chemotherapy. Data from 1961 to 1965 of the screening trials of the Eastern Clinical Drug Evaluation Program were utilized. Response and location data extensive enough for analysis represented 6 sites of primary origin and 6 metastatic site groups, totalling 1687 lesions. Analysis of percentage reduction in tumour size after chemotherapy regimens of up to 60 days revealed a significant amount of variation associated with metastatic sites and a non-significant amount associated with sites of primary origin. Advanced primary tumours showed marked variation in responsiveness and some showed a difference in response to different drug groups. Generally, metastases responded better than the advanced primaries from which they were derived, except for those from breast tumours.