Editing Colon cancer (section)

== '''Surgery''' ==

** Principles
*** Gentle surgery, avoiding manipulation of the tumour
*** At least 12 nodes required, but generally around 20 are resected
*** Aim for a free margin of 5cm to minimise risk of recurrent cancer and capture perivisceral lymph nodes; however, if is more complex than that if we follow guidelines from JSCCR
**** If there is a clear main vessel, resect 5cm past it, or 10cm past the tumour in the opposite direction
**** If the tumour is between two main vessels, then 5cm past each main vessel is necessary
***
*** Tension-free anastomosis
*** Avoid injury to vascular supply of the colon, including marginal artery
*** Central venous ligation should be performed
*** Aim for D3 resection - there is a survival benefit, although it is small, and only relevant for more advanced disease. However, it is almost impossible to accurately stage these cancers pre-op, so best to perform D3 resection by default.
***
** Open vs laparoscopic
*** Favourable recovery with minimally invasive
*** Oncologic outcomes non-inferior, with similar disease-free survival and local recurrence rate
*** No clear advantages to robotics yet
** Right-sided cancers
*** Right hemicolectomy
*** Excise the lymphatic tissue around SMV en bloc for a complete lymphadenectomy
***
** Transverse colon cancers
*** Mostly extended right hemicolectomy - need to also divide middle colic vessels at the origin
***
** Splenic flexure cancers
*** Controversial - extended right hemicolectomy or left hemicolectomy (segmental) or extended left hemicolectomy or subtotal colectomy
**** '''Extended RHC''' would take both branches of middle colic and go round as far as upper descending colon, but is really only an option when you think lymphatic drainage will definitely be to the middle colic pedicle
**** '''Segmental left hemicolectomy''' would involve IMV ligation, left colic artery division at origin, sometimes the left branch of middle colic, and anastomosis between transverse colon and descending colon. Still usually gets enough nodes to stage.
**** '''Extended left hemicolectomy''' ligates left branch of middle colic with IMA at origin, then joins distal transverse to sigmoid. Not thought to be a good operation by some colorectal surgeons as it is non-anatomical.
**** '''Subtotal colectomy''' - perhaps the best oncological operation, given total resection of middle colic and IMA pedicles, but worst functional outcome
*** In one study, 96% of normal splenic flexure lymphatic drainage was to left colic/IMA pedicle, so argument for middle colic lymphadenectomy is probably not warranted
*** Key factors:
**** Younger patients can handle the longer operation and functional impairment of subtotal colectomy better
**** Older patients may opt for a segmental left hemicolectomy to preserve function
***
** Left-sided cancers
*** Left hemicolectomy - high ligation of IMA, IMV ligation, splenic flexure mobilisation, and anastomosis between left colon and proximal rectum with circular stapler
***