Does the surgical removal of a cancerous tumor necessarily result in cancer cells to be spread to other parts of the body via the bloodstream?

Cancer treatment: No. If the neoplasm is thought to be limited and amenable to excision or complete removal, then it is the treatment of choice. Adjuvant chemo and/or radiation are used to kill residual microscopic local or distant metastatic disease. It is not a good idea to just debulk the malignancy. The goal is to excise or remove entirely all gross disease. What "spills" in blood stream is insignificant.