I hope I understood your question properly:

If you just want a broad spectrum answer to what is different between your tumor samples, then you can use a product like the R&D mouse cytokine array (or a similar product) . It doesn't cover all the cytokines and chemokines, but it will give you a good first pass look. This, of course will not help you at all if you are interested in specific cellular sub-types within the tumor. I used it for exactly that purpose and found the insight useful.

I would use IHC to demonstrate cell specificity. Tumor cells are comprised of many "accessory" cells that are also capable of secreting cytokines. In our mouse model of prostate cancer, we used tissue to look at cytokines via IHC to correlate cytokines with a progressive phenotype. We also processed excised tissue for protein and mRNA to analyze various cytokines. We used ELISA sera to measure circulating cytokines. Although, you can also use the Luminex system to detect circulating levels of cytokines. Finally, we have used the R&D mouse cytokine array for several studies and found it quite reliable and easy to use.

Thank you all very much for sharing your valuable experiences with me, as well as advice. I greatly appreciate!