earlies1 observations in the 0 studies oE metabolism of malignant tuniors was that tumor cells produce lactic acid at a rate of about 25, of their fresh weight per hour.l?
Lactic acid was found to be increased in the blood that passes through a n experimmrai or a human tumor.5 'This increase might be cauqetl by increased g[) col) sis, decrcwecl ox-itLition of lactic acid, 01-both. T h e lactic. dehytlrogcnase (I 1)) a( tivity i n 20 normal tissues . t i i d 19 different tumois i n mice and i n rats was iri\estigated b y Meister , $) aiid it was found that rhe values for the tunioxs wrcre the same as or higher than those for t h c c oi responding nor-inn1 tisrues. T h e LD o f rli;il~tIom~osarconia was lower than that of striatcd muscle. T h e serum l a c tic tlehytlrogenase (\I 11) was found to incrcasc on tumor ti;ins~~l;ciit;i~ioii and to decrease on tumor i e p e\ion.?
Hill. anti L,cviG slutlied the SLD i n p-ticlit5 ~. i t l i neoplastic-tlisea rlevatc.d levels i n I10 oiit ol 156 cases. T h e TI) lewls were followeil iri 7 Irukemic paiitvits for ;I polonget1 pcriotl of time? during which the SI D levels closely reflected the tlinical state of the patient. T h e authors also ol,wi~ed that the S I ~ i i i childrcn is higher tIi,rn i n adults and that i t declines to adult Ie\els at about the age of 14 years. From t hese findings the conclusion was drawn that \I 1) might in some w;ty bc connected with growth processe5, althorigh i t was cmphasi7ed t h a t the biological signific:iiicr of LD in serum I . .. . _ . -From the Laboratory Scrvic e, ":terms Adn~inistratiori Center, hfartinshnrg, W . Va.. and the Department of Pathology. The Gcorgc: Washington ITnivcrsity School of Medicine, Washington. 1j.C. .4ided by a grant (266.4) lroni thr American Cancer The author wishes to ~Ii;iirh the Department of Radiology, particularly Dr. flcrman I.itwer and Miss Flora Lee Steely. and the Tkpartment of Surgery for their ready co-operation. Thanks sre also due 10 Mrs. Aileen Soiiza for her skillfiil lrchniral assistanre. Society, Inc.