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Neoadjuvant therapy is the administration of therapeutic agents before a main treatment. One example is neoadjuvant hormone therapy prior to radical radiotherapy for adenocarcinoma of the prostate. Neoadjuvant therapy aims to reduce the size or extent of the cancer before using radical treatment intervention, thus making procedures easier and more likely to succeed, and reducing the consequences of a more extensive treatment technique that would be required if the tumor wasn't reduced in size or extent.
Another related concept is that neoadjuvant therapy acts on micrometastatic disease. The downstaging is then a surrogate marker of efficacy on undetected dissemination, resulting in improved longtime survival compared to the surgery-alone strategy.
This systemic therapy (chemotherapy, immunotherapy or hormone therapy) or radiation therapy is commonly used in cancers that are locally advanced - where clinicians plan an operation at a later stage. The use of such therapy can effectively reduce the difficulty and morbidity of more extensive procedures.
The use of therapy can turn a tumour from untreatable to treatable by shrinking the volume down. Often it can be unclear which surrounding structures are directly involved in the disease and which are just showing signs of inflammation. By administering therapy a distinction can often be made. Some doctors give the therapy in the hope that a response will be seen so that they can then decide what is the best course of action. Unfortunately, not everyone is suitable for therapy in this way because it can be extremely toxic. Some patients react so severely that further treatments, especially surgery, are precluded because the patient is rendered unfit for anesthetic.
See also 
Further reading 
- Valentini, Vincenzo; Coco, Claudio; Picciocchi, Aurelio; Morganti, Alessio G; Trodella, Lucio; Ciabattoni, Antonella; Cellini, Francesco; Barbaro, Brunella et al. (2002). "Does downstaging predict improved outcome after preoperative chemoradiation for extraperitoneal locally advanced rectal cancer? A long-term analysis of 165 patients". International Journal of Radiation Oncology • Biology • Physics 53 (3): 664–74. doi:10.1016/S0360-3016(02)02764-5. PMID 12062610.
- Tollefson, Matthew K.; Boorjian, Stephen A.; Farmer, Sara A.; Frank, Igor (2012). "Downstaging to non-invasive urothelial carcinoma is associated with improved outcome following radical cystectomy for patients with cT2 disease". World Journal of Urology. doi:10.1007/s00345-012-0855-8. PMID 22447397.
- Rosenblatt, Robert; Sherif, Amir; Rintala, Erkki; Wahlqvist, Rolf; Ullén, Anders; Nilsson, Sten; Malmström, Per-Uno; Nordic Urothelial Cancer Group (2012). "Pathologic Downstaging is a Surrogate Marker for Efficacy and Increased Survival Following Neoadjuvant Chemotherapy and Radical Cystectomy for Muscle-Invasive Urothelial Bladder Cancer". European Urology 61 (6): 1229–38. doi:10.1016/j.eururo.2011.12.010. PMID 22189383.