Regional differences in the incidence and growth of mouse tumors following intradermal or subcutaneous inoculation.

Tumor cells inoculated intradermally or s.c. into more cranial regions of the lateral trunk show strikingly greater tumor growth and development than do similar cells injected more caudally. At low tumor cell doses the incidence anteriorly may be double that found posteriorly and tumors become detectable more rapidly anteriorly; at higher cell doses the anterior:posterior ratio of tumor weight may be 4:1. The effect appears to be independent of the type of tumor used (mastocytoma, sarcoma, teratoma, lymphoma, or adenocarcinoma) and of the strain of mouse host; it does not appear to be influenced by the sex of the host animal, the immunogenicity of the tumor, or the immunological competence of the tumor recipient. The results are discussed both in terms of practical considerations for developing adequate tumor transplantation and treatment protocols and in terms of the biological significance in relation to spontaneous or induced oncogenesis.