Rectal Ca

Anatomy

  • Lower Rectum
    • 3-6cm from anal verge
  • Mid-Rectum
    • 6-9cm from anal verge
  • Upper Rectum
    • 9-12 to 15cm
    • From sacral prominence to peritoneal reflection
    • ant and lat is covered by peritoneum
    • posteriorly —> no serosal covering
    • @ rectovesical or rectouterine pouch
      • Rectum is completely extra-peritoneal

Where is upper limit of rectum:

  • At ~12cm is upper limit of retroperitoneal portion of rectum ==> higher up —> rectum is periotonealized
  • When defining rectum from sigmoid —>
    • Rectum at least is partially retroperitoneal
  • Externally —> longitudinal coat of muscle from tinea spread

Junction with anal canal?

  • At level of levator ani rectum enters the anal canal
  • Anorectal ring —> at level of puborectalis m.

Lymphatic Drainage

  • Upper Rectum —> Sup hemorrhoidal a. —> inf mesenteric a.
  • Within 6cm of anal verge —> Middle hemorrhoidal a. —> internal iliac; obturator fossa
  • If below dentate line —> Inguinal nodes and ext. iliac

Autonomic Nerves

  • Hypogastric Plexus <— Sympathetic Trunks ( lateral to mesorectum; along the lateral pelvic side walls)
  • S2, S3, S4 —> parasympathetic fibers

Sympathetic and parasympathetic fibers joins at tip of seminal vesicles ( anterior )

Staging

  • T and N stage both are prognostic factors
  • Number of nodes —> 12-20 is optimal
    • percentage of positive nodes is prognostic
  • Close and positive margins are poor prognostic factros

Lymph Node Metastasis

Tumour Stage Chance of LN+
T1 6%
T2 20%
T3 65%
T4 78%

Investigations

  • History
    • Fatigue
      • 2nd to Anemia
    • Weight loss
    • Low appetite
    • Rectal bleeding
    • Change in Bowel habits
      • Constipation
      • Decrease stool caliber
  • Physical
    • Paleness
    • Cachetic
    • Abdominal exam
      • Liver ( tenderness/mass )
    • Sitting comfortable?
    • Inguinal nodes
    • DRE
      • Distance of tumour from anal verge
      • Any involvement of anal sphincter
      • Amount of circumferential involvement
      • Clinical fixation
      • Sphincter tone
  • CBC
  • LFT
  • KFT
  • CEA
    • High CEA associated wioth poor survival
  • Imaging
    • Colonoscopy
    • Barium Enema
      • Evaluate the remainder of the bowel —> R/O synchronous tumours
    • Endorectal US
      • Operator and skill dependent
      • Defines five interface layers of rectal walls:
        • Mucosa
        • Muscularis mucosa
        • Submucosa
        • Muscularis Propria
        • Perirectal fat
        • Hence 75-95% acccuracy in T stage
        • Less accurate in Nodal stage ( 60-80% )
    • CT
      • Overall accuracy:
        • For T stage: ~80%
        • For Nodal stage: <80%
    • MRI
      • Endorectal coil MRI
        • Discrement of the layers of the bowel wall
      • Accuracy better than CT but nothing close to even 90%
      • Advatnages of MRi to EUS:
        • Assessment of stenotic tumours
        • Assessment of proximal tumours
        • Less operator dependent
        • Can assess LN status based on characteristics rather than size
    • CXR

Treatment

Mainstay of treatment is surgical resection.

Stage I

  • Abdominal Resection.
  • Abdominal-perineal resection(APR)
    • Comparing to TME, APR does not improve the outcome
    • APR vs TME:
      • Additional tissues removed with an APR:
        • Anus
        • Anal canal
        • Portion of the levator muscles
        • Ischiorectal fat
        • These areas are rare sites for retrograde involvement or local recurrence
        • If margin is 1cm clear —> no advantage
  • Local excision can be considered.
    • Different type of local excisions:
      • Trans-anal local resection if:
        • Early stage
        • Less than 40% of circumference
        • <3cm
        • Surgical margin should be >3mm
        • Mobile tumors (non-fixed tumours)
        • Within 8-10cm from anal verge
        • No LVI
        • Well or moderate differentiation
        • This approach needs to be used with caution
        • However further studies on the way
          • ACOSOG Protocol Z6041
            • US T2
            • Naoadj CRT and local excision needs tatooing of primary tumour as goos response may make it hard to identify
            • Neoadj Capecitabine; Oxaloplatin + RT —> Local Excision
      • Trans-anal endoscopic microsurgery (TEMS)
        • Video-endoscopic magnification
        • Recurrence as high as 30% is reported!
      • Posterior proctotomy (Kraske Procedure)
        • Useful for large posterior lesions
        • Posterior longitudinal inxision
          • Just above the anus
        • removal of coccyx
        • Full-thickness local excision
      • Trans-sphincteric local excision (Bevan's or York-Mason's approach)
        • Same as Kraske only anal anal sphincter is divided posteriorly

Post-op CRT if:

  • T2
  • T1 and
    • LVI
    • Poor differentiation
    • Close margin
      • <3mm

Stage II and III

  • Surgery goals
    • Preserve intestinal continuity
    • Preserve sphincter mechanism if possible
    • Maximizing tumor control
  • Important factors:
    • Depth of invasion
    • Location of tumour
  • Three subdivision in rectum:

Sphincter-preserving operation

  • Preserve the lateral musculature
    • for a functional sphincter complex
  • Then to improve on margin status
    • Intersphincteric resection
      • Partial sphincteric resection

Surgical resection with 1-2cm mucosal margin

  • Abdominal-Perineal Resection
    • For tumours within 6cm to anal verge
    • Remove the entire sphincter complex
    • Permanent colostomy
  • Low colo-anal anstomosis
    • Within 1-2cm of dentate line
      • Hence can have a 1cm margin
    • Requires a diverting loop colostomy ==> protect the healing suture lines ==> reverse after 4-6wks
  • Total Mesorectal Excision (TME)
  • Removal of
    • Tumour
      • with adequate margin
    • Drianing LN
      • Proper staging and reduce recurrence
      • Within the mesorectum
  • A sharp dissection occurring in an avascular plane beyond the perirectal fat that is beyond the region where most of the nodes are located.
  • The specimen is typically shiny and bilobed in contrast to the irregular and rough surface after a blunt dissection
  • Goals of TME:
    • Clear involved lymph nodes
    • Clear radial margins
      • Been shown to be more important with respect to LR risk than the distal mucosal margin
TME.png

Most involved LN for rectal ca are found within mesorectum.

  • Sharp dissection
  • Beyond the peri-rectal fat
  • Will give a good radial margin
    • 1cm is adequate
    • More important than distal margin
  • Side Effects:
    • Disruption of parasympathetic nerves ( located proximal to mesorectum )
      • Erectile dysfunction
      • Bladder dysfunction

Multimodality Treatment

  • Standard is pre-op ChemoRT.
  • Pre-op RT has shown constantly benefit in LR.
  • Mixed data for OS but one meta-analysis has shown survival benefit.
  • Chemo concurrent with RT increase the benefit.
  • Pre-op vs post-op RT is superior in terms of LR.
  • One situation RT alone pre-op may be used:
    • cT2N0; distal which standard is APR
    • If patient refuses APR one can consider pre-op RT

Pattern of local failure

T stage Risk of local recurrence after surgery alone
T1 <5%
T2 10%
T3 20%
T4 30%<
  • Any node positive disease —> risk of LR: 30-50%
  • Location of tumours: lower tumours have higher chance of LR
  • Experience of surgeon

Adjuvant RT

  • Most studies have shown a 50% decrease in local failure rate by use of RT.
  • Additional benefit with use of concurrent 5FU.
Pre-op RT
  • Pre-op RT decrease local recurrence.
  • Pre-op RT and survival?
    • Swedish study is the only one which showed OS benefit
    • Two meta-analysis
      • One showed OS benefit
      • CRCC group meta-analysis showed death rate decrease in pre-op only
22.png
  • Dutch study
    • Arms:
      • TME alone
      • Pre-op short course RT (25Gy in 5fr) + TME
Untitled.png
  • Swedish study
    • The only pre-op RT study which showed OS benefit
    • cT1-3
    • Arms:
      • Surgery alone
      • 25 Gy in 1 week —> surgery 1 week later
    • Results:
    • Pre-op RT ==>
      • Significant decrease in LR (12% vs. 27%; p <.001)
      • Significant improvement in 5-year OS (58% vs. 48%; p = .004)
        • 13 years OS: (38% vs. 30%; p = .008)
  • Dutch CKVO 95-04 trial
    • cT1 to T3
    • Arms:
      • TME alone
      • Intensive short-course pre-op RT —> TME
    • Results:
      • Pre-op RT:
        • Decreased LR (8% vs. 2%; p < .0001)
        • No difference in the 2-year survival rate (82%
      • Acute toxicity rates:
        • Neurotoxicity: 10%
        • Perineal wound complications: 30%
        • Postoperative leaks: 10%
Post-op RT
  • NSABP study
    • Arms:
      • Surgery alone
      • Surgery + RT
    • Local recurrence:
      • 16% vs. 25%; p = .06
  • Medical Research Council (MRC) trial
    • Role of adj RT only
    • LR: 21% vs. 34%; p = .001
Pre-op vs Post-op ChemoRT
  • Advantages of post-op:
    • Avoiding overtreatment
    • Better pathologic staging
  • Disadvantages of post-op:
    • Higher rates of local recurrence
    • Higher rates of acute and chronic toxicity
    • Lower chance of sphincter preservation

This is based on German Trial:

  • uT3-4 and/or LN+
  • <16 cm from the anal verge
  • Arms:
    • Pre-op ChemoRT (with Continuous Infusion 5-FU during weeks 1 and 5) vs Post-op ChemoRT
  • Results:
    • Pre-op ==>
      • Decrease in rates of local failure (6% vs. 13%; p = .006)
      • Decrease in acute toxicity (27% vs. 40%; p = .001)
      • Decrease in chronic toxicity (14% vs. 24%; p = .012)
      • Better sphincter preservation (39% vs. 20%; p = .004)
  • NSABP R-03 study
    • cT3-4
    • Induction Chemo then randomized to:
    • Arms:
      • Pre-op vs Post-op ChemoRT
    • Results:
      • Pre-OP ==>
        • Significant improvement in 5-year DFS (65% vs. 53%; p = .011)
        • Borderline significant improvement in 5-year OS (75% vs. 66%; p = .065)
        • No difference in 5-year LR rates (11%)

Rectal Ca Radiation Technique