As far as possible, surgery should be the first choice to deal with the problem.
Stenting is done when the patient is too weak to undergo surgery at the point of presentation. The patient may be dehydrated and have severe electrolyte imbalance due to the obstruction. In good hands, stenting produces good results, and allows both the patient and surgeon to buy time for proper stabilisation and work-up before definitive surgery. For this reason stenting is often called the "bridge to surgery".
Another option in obstructed cases is to create a temporary diversion colostomy to relieve the obstruction. This is often done in advanced cases where the tumour is so large and surgery becomes dangerous. The stoma relieves the obstruction, and the patient may be stabilised and then undergo chemo and/or radiotherapy to down-stage the tumour before surgery.