A flexible endoscopic instrument insertable within a single instrument channel of a flexible endoscope, the endoscopic instrument comprising: a cutting assembly configured to resect material at a site within a subject, the cutting assembly including an outer cannula and an inner cannula disposed within the outer cannula, the outer cannula defining an opening through which material to be resected enters the cutting assembly, the cutting assembly being sized, at least in thickness and in length, such that the endoscopic instrument can be slidably inserted into the instrument channel of the endoscope; a flexible portion shaped, sized and configured to be inserted within the instrument channel, while a remaining portion of the endoscopic tool is configured to remain outside the instrument channel of the endoscope, the flexible portion comprising: a flexible outer tubing coupled to the outer cannula and configured to cause the outer cannula to rotate relative to the inner cannula, the flexible outer tubing having an outer diameter that is smaller than the instrument channel in which the flexible endoscopic instrument is insertable, the flexible outer tubing having a length that exceeds the length of the endoscope and that is at least 100 times larger than an outer diameter of the flexible outer tubing; a flexible torque coil having a portion disposed within the flexible outer tubing, the flexible torque coil having a distal end coupled to the inner cannula, the flexible torque coil being configured to rotate the inner cannula relative to the outer cannula to resect the material to be resected; a proximal connector coupled to a proximal end of the flexible torque coil and configured to engage with a drive assembly that is configured to cause the proximal connector, the flexible torque coil and the inner cannula to rotate upon actuation; an aspiration channel having an aspiration port configured to engage with a vacuum source, the aspiration channel being partially defined by an inner wall of the flexible torque coil and an inner wall of the inner cannula and extending from an opening defined in the inner cannula to the aspiration port; and an irrigation channel having a first portion defined between an outer wall of the flexible torque coil and an inner wall of the flexible outer tubing and configured to carry irrigation fluid to the aspiration channel. a cutting assembly configured to resect material at a site within a subject, the cutting assembly including an outer cannula and an inner cannula disposed within the outer cannula, the outer cannula defining an opening through which material to be resected enters the cutting assembly, the cutting assembly being sized, at least in thickness and in length, such that the endoscopic instrument can be slidably inserted into the instrument channel of the endoscope; a flexible portion shaped, sized and configured to be inserted within the instrument channel, while a remaining portion of the endoscopic tool is configured to remain outside the instrument channel of the endoscope, the flexible portion comprising: a flexible outer tubing coupled to the outer cannula and configured to cause the outer cannula to rotate relative to the inner cannula, the flexible outer tubing having an outer diameter that is smaller than the instrument channel in which the flexible endoscopic instrument is insertable, the flexible outer tubing having a length that exceeds the length of the endoscope and that is at least 100 times larger than an outer diameter of the flexible outer tubing; a flexible torque coil having a portion disposed within the flexible outer tubing, the flexible torque coil having a distal end coupled to the inner cannula, the flexible torque coil being configured to rotate the inner cannula relative to the outer cannula to resect the material to be resected; a flexible outer tubing coupled to the outer cannula and configured to cause the outer cannula to rotate relative to the inner cannula, the flexible outer tubing having an outer diameter that is smaller than the instrument channel in which the flexible endoscopic instrument is insertable, the flexible outer tubing having a length that exceeds the length of the endoscope and that is at least 100 times larger than an outer diameter of the flexible outer tubing; a flexible torque coil having a portion disposed within the flexible outer tubing, the flexible torque coil having a distal end coupled to the inner cannula, the flexible torque coil being configured to rotate the inner cannula relative to the outer cannula to resect the material to be resected; a proximal connector coupled to a proximal end of the flexible torque coil and configured to engage with a drive assembly that is configured to cause the proximal connector, the flexible torque coil and the inner cannula to rotate upon actuation; an aspiration channel having an aspiration port configured to engage with a vacuum source, the aspiration channel being partially defined by an inner wall of the flexible torque coil and an inner wall of the inner cannula and extending from an opening defined in the inner cannula to the aspiration port; and an irrigation channel having a first portion defined between an outer wall of the flexible torque coil and an inner wall of the flexible outer tubing and configured to carry irrigation fluid to the aspiration channel.