It is certain that neuroimmune mechanisms play a role in host defence
against cancer. However, this interaction is highly complex and many.
variations are possible according to the nature of the neoplasms invol
ved. There are indications that adaptive immunity is present in a sign
ificant Proportion of tumor bearing hosts, and this defence may be boo
sted by specially designed vaccines and cytokines. Natural immune medi
ators are also implicated in resistance against tumor development. Her
e we review the evidence suggesting that hormonal manipulation of the
host can result in the elevation of immune defences against cancer. Su
ch manipulation strengthens both the adaptive and natural immune defen
ces of the host, both of which play significant roles. Natural defence
mechanisms are boosted by cytokines and hormones during febrile react
ions which are now known as the acute phase response. It is suggested
that hormonal stimulation of immune mechanisms coupled with the usual
immunostimulants already in use may be employed to good advantage for
the combination immunotherapy of cancer. Modern molecular biology appr
oaches permit the development of laboratory monitoring procedures whic
h may be used for the prediction and follow-up of therapeutic success.