• Invasion through the bowel wall into the perirectal fat – an important predictor of local recurrence and survival• Extramural venous invasion is an adverse prognostic factor
Lymph node spread
• From the level of the tumour cranially within the mesorectum – proximal blockage (e.g. extensive adenopathy) may cause retrograde spread with lower rectal tumours rarely spreading to the inguinal nodes• Pelvic side wall spread is unusual
Haematogenous spread
• Liver (via the portal vein)
PEARLS
• Involvement of the circumferential resection margin (CRM) is an adverse prognostic feature (including disruption during surgery)• Perforation of the peritoneal membrane can result in transcoelomic spread as well as an increased risk of recurrence• Transcoelomic spread favours the lower right small bowel mesentery and the pouch of Douglas
• 70% of tumours arise within the pancreatic head• Tumour spreads by direct perivascular and perineural invasion• Head/uncinate process tumours: these usually extend along the SMA and mesenteric root• Body/tail tumours: these usually infiltrate the coeliac, hepatic or splenic arteries• Local invasion can involve the stomach, duodenum and retroperitoneum
Lymph node spread
• Early micrometastases at presentation are common• Primary drainage: superior, inferior, anterior, posterior and splenic lymph nodes• Secondary drainage: porta hepatis, common hepatic, coeliac, mesenteric root lymph nodes• Tertiary drainage: peri-aortic and distal superior mesenteric lymph nodes
Haematogenous spread
• Early micrometastases at presentation are common• These usually involve the liver and peritoneal surfaces
PEARL
• Usually only tumours of the head and uncinate process are surgically resectable (tumours of the body and tail usually have perivascular or perineural metastases at presentation)
• Vascular invasion of the portal or hepatic veins
Lymph node spread
• Spread to lymph nodes along the hepatoduodenal ligament – with a propensity to spread to the portocaval lymph node chain as well as the anterior and posterior pancreaticoduodenal chain
Haematogenous spread
• Less common than with HCC – remote metastases are usually to the lung (less commonly to bone, the adrenals and peritoneum)
chest wall invasion 
brachial plexus invasion (Pancoast’s tumour)
ipsilateral mediastinal (± subcarinal) nodes (N3)
SCLCs have usually metastasized at presentation
lesser curvature 
greater curvature 
suprapyloric• Extraperigastric: left gastric 
common hepatic 
coeliac 
splenic hilum and artery 
hepatic pedicle 
retropancreatic 
mesenteric root 
middle colic 
para-aortic• NB: retropancreatic, para-aortic and mesenteric nodes are classified as M1 metastatic disease
a similar number will have peritoneal metastases
ipsilateral adrenal 
adjacent viscera (including muscles)• Renal vein invasion (± IVC)
direct connections with the thoracic duct and mediastinum also exist
Get Clinical Tree app for offline access
subsequent invasion of adjacent pelvic organs and the pelvic side wall by direct invasion