<unk>  is the administration of<unk> utic agents before a main treatment. One example is<unk>  hormone<unk>  prior to radical radiotherapy for adenocarcinoma of the prostate.<unk>  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<unk>  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<unk>  (chemotherapy, immunotherapy or hormone<unk>  or radiation<unk>  is commonly used in cancers that are locally advanced - where clinicians plan an operation at a later stage. The use of such<unk>  can effectively reduce the difficulty and morbidity of more extensive procedures.
The use of<unk>  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<unk>  a distinction can often be made. Some doctors give the<unk>  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<unk>  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.
Neoadjuvant therapy
Adjuvant therapy
Neoadjuvant chemotherapy
Hormone therapy
Chemotherapy
Hormonal therapy 
Radiation therapy
External beam radiotherapy