Surgery is the mainstay of therapy for most solid tumors but even with complete removal of the tumor, many patients harbor microscopic residual tumor cells and ultimately die of relapse disease. This research group has demonstrated that the immediate postoperative period is a uniquely susceptible time for the development of cancer recurrence due to profound immune system suppression following major surgery. Thus, the postoperative period is a critical time to intervene, by supporting or further stimulating the immune system to reverse the immunosuppressive effects of surgery and possibly interfere with mechanisms responsible for postoperative cancer growth and metastases. Based on this information, this study will test two commonly used drugs, tadalafil and the influenza vaccine, to help improve immune function after surgery in patients with primary abdominal cancers. Tadalafil has been found to decrease immune suppressive cells called Myeloid Derived Suppressor Cells (MDSC) and administration of the influenza vaccine prior to surgery improves the function of immune cells called natural killer cells. If the subsequent Phase II trials are also successful, the use of these two established drugs could be quickly incorporated into future treatment methods for solid tumors to prevent metastases and achieve long-term survival.
Trial Registration: ClinicalTrials.gov Identifier: NCT02998736