It is a truism to state that in cancer the extent to which the disease has spread (stage) is probably the most important factor determining patient prognosis and must be given prime consideration in evaluating and comparing different therapeutic regimes. Because of this, clinical screening tests (such as a rectal exam proctoscopy and colonoscopy), if tissue that is not normal is found, should include analyses contributing to the patient disease stage classification. However, the difficulty involved in this, principally due to the absence of reliable early prognostic indices of the disease stage, makes the cancer patients' treatment full of problems and risks. By a retrospective statistical study on pre-surgery peripheral blood immunological parameters of our groups of colorectal cancer patients and healthy subjects, we evaluated our previously suggested possibility of defining stage prognostic indices by parameter blood range values, evaluating their ability in the stage classification compared to the pTNM method. We have investigated the serum levels of various cytokines and cytokine receptors, leukocyte surface markers, peripheral blood mononuclear cell (PBMC) cytokine production and PBMC proliferative response. Statistically significant correlations between a variety of these immunological parameters and the disease stage were found, but as a clinical patient screening of all parameters is quite expensive, to identify the greatest stage weighting parameter and the respective blood range values, we performed a multivariate statistical analysis. We found that the blood ranges of IL-4 serum level and the PBMC proliferative response to anti-CD3 monoclonal antibody (mCD3) stimulus may be reliable prognostic indices which may contribute to an early disease stage classification in colorectal cancer patients, since they seem to be valid as the pTNM method. Moreover, as the immunological prognostic indices could be a useful tool to evaluate the patient immune response, they may also improve the definition of the patient's stage classification for the selection of treatment and restaging procedures for the evaluation of the treatment benefit and recurrent disease.