Cancer cachexia is transmissible in plasma

The cause of cancer cachexia is unclear. Tumors may be competing with the host for ingested nutrients or may be releasing some factor that actively inhibits energy utilization. To explore these questions, plasma was sterilely collected and pooled from 103 terminally cachectic Fischer 344 rats implanted with an experimental sarcoma. Control plasma was collected in similar fashion from 138 nontumor-bearing rats (NTBP). Plasma from tumor-bearing rats (TBP) or NTBP was continuously infused in a randomized, blinded fashion for 4 days into 20 normal rats. During infusion, food intake and nitrogen excretion were measured daily. At sacrifice, body weight and organ masses were determined. Rats receiving TBP demonstrated an immediate and profound anorexia compared with those receiving NTBP. Total food intake during treatment was 31.2 +/- 3.3 (g +/- SEM) in the TBP group versus 48.2 +/- 2.8 in the NTBP group (P less than 0.001 by t test). Likewise, the total decline in body weight was greater in the TBP group as compared with the NTBP group (-35.2 +/- 3.4 versus -14.6 +/- 4.0, P less than 0.001). Mean daily nitrogen balance during treatment was negative in the rats receiving TBP (-14.5 +/- 20.1 mg +/- SEM) while remaining highly positive in the rats receiving NTBP (110.7 +/- 19.3, P less than 0.002). Finally, cardiac and gastrocnemius muscle masses were decreased, while hepatic mass was unaffected. These data demonstrate that the syndrome of cancer-associated cachexia is transmissible in plasma and therefore may be mediated by a circulating molecule or molecules. Identification and purification of the molecule(s) responsible for this effect would have obvious clinical benefits.