Rectal cancer

Section: Colorectal Sub-section: Colorectal cancer Curriculum: Curriculum, page 21

Definition

• Surgical: convergence of teniae coli, sacral promontory
• Radiological: take-off of sigmoid mesentery.
• Distance: 12 (US) or 15 cm (UK) from the anal verge.

Local recurrance

Risk factors for local recurrence:

• Size of primary
• Involvement of CRM
  • Main factor; which can also be modified by optimal treatment
  • Postive CRM defined as tumour within 1mm margin of specimen
• Distal location of tumour
• Extramural vascular invasion (n.b. also higher predictor of distant mets than nodal status; usually locoregional nodes will be removed by TME).
• Tumour differentiation
• Nodal status (N stage)
• Extent of extramural spread (T stage)
• Peritoneal involvement by tumour (T stage)

Neoadjuvent treatment

Radiotherpay

• Uses ionising radiation to eliminate cancer cells.
• Reduce the risk of local recurrence compared with surgery alone.
• Although cancer-specific survival is improved there was is definite evidence of any impact on overall survival.

History

• Short course (25 Gy in five daily fractions of 5 Gy)
  • Adjuvant short course
    • Swedish rectal cancer trial (RT decreases LR)
      • The first to report an improvement in overall survival
      • decreased local recurrence from 27 to 11%
• Neoadjuvent short course (SCT + TME vs TME + selected therapy)
  • Dutch TME trial and MRC CR07 (RT with TME improves LR)
    • Local recurrence from 11% to 5%
    • No difference in mortality, leak or overall survival
• Addition of 5-FU and Leucovorin to Long course radiotherapy (50.4 Gy over 5 weeks)
  • EORTC 22921 trial and FFCD 9203
    • Both showed the risk of local recurrence was reduced from 15% to 8–10% in favour of CRT
  • The German Rectal cancer group (Give RT pre-op)
    • compared Preoperative versus Postoperative Chemoradiotherapy for Rectal Cancer
    • Lower rate of local recurrence (6% vs. 12%), reduced acute and late toxicity in favour of preoperative CRT
• CRT vs SCRT
  • Polish Trial
  • The Trans Tasman Radiation Oncology Group
    • No difference found
• Short course with delay
  • Stockholm III
    • Increase cPR and less surgical complications
• PROSPECT trial, page 1
  • In patients with locally advanced rectal cancer who were eligible for sphincter- sparing surgery, preoperative FOLFOX was noninferior to preoperative chemoradiotherapy with respect to disease-free survival.

Inidications

UK NICE recommend consideration of neoadjuvant radiotherapy for high-risk stage II and all stage III rectal cancer.

Purpose

• Reduce risk of local recurrence
• Shrink locally advanced rectal cancer to facilitate successful resection
• No impact on overall survival
  • Although studies showing improved DFS and distant recurrence rates with TNT.
• Benefits of neoadjuvant as opposed to adjuvant:
  • Undisturbed pelvic anatomy – less chance of SB irradiation
  • Better oxygenated tissue (better radiosensitivity)
  • Better compliance
  • Allows for tumour response assessment (prognostication)
• Indications:
  • (DisTANCE)
    • Dis -tance from sphincter (low tumours have smaller mesorectum, narrow distally)
    • T stage
    • Anal sphincter involvement
    • Nodes
    • CRM
    • EMVI
  • Upper rectal
    • Not indicated unless T4b
    • Treat like colonic cancer
  • Mid rectal
    • Local advanced
      • T3/T4 or any N stage i.e stage II or stage III
  • Low rectal cancer
    • T1 - surgery
    • T2 - neoadjuvent if close to sphincters
    • The rest neoadjuvent treatment
    • Can consider in any T stage if discussion regarding sphincter preservation
• Timing of restaging and surgery
  • Usually at 6-10 weeks with surgery at 12-14 weeks.
• Complications/toxicity of radiotherapy:
  • Early: perineal wound breakdown, diarrhoea, proctitis, UTI, SBO, leucopenia and VTE
  • Late: bowel, urinary and sexual dysfunction, sterility, new malignancy – lymphoma, sarcoma
• Total Neoadjuvant Treatment

Adjuvant chemotherapy:

• Trials have not shown significant benefit.
• Often poor effectiveness due to treatment delay and poor compliance. Morbidity from radiotherapy and surgery reduce tolerance to AC. Ileostomy also impairs delivery with diarrhoea.
• Despite poor evidence some groups recommend adjuvant chemotherapy to all patients who underwent pre-operative radiotherapy (excluding TNT patients)

Surgery

Decision making on type of operation:

Patient factors

• Local – previous radiotherapy, obstetric injury and low anastomosis all risks for poor function and should consider permanent stoma. Ask about flatus incontinence history.
• Systemic – comorbidities Tumour/disease factors
• Biology
• Site
• Extent/fixity, e.g. early T1 may be suitable for local excision.
• Imaging characteristics: CRM threat, EMVI, local invasion of sphincter complex.

Extent of resection

TME – for middle and lower rectal cancers (Heald 1982)

• Extrafascial excision for low to mid rectal cancers
• Reduced LR from 20-30% → 5-10% (McCall 1995)
• Mechanism:
  • Tumour deposits have been found in the mesorectum up to 4 cm caudally to tumour in poorly differentiated cancers
  • Low rectal tumours – reasonable to have 1 cm margin, given that mesorectum eventually disappears as it approaches the pelvic floor sphincter muscle complex. 1 cm margin not associated with increased recurrence.
  • Upper rectal tumours – divide the mesorectum tangentially 5 cm distal to primary tumour, maintaining benefits of bowel function and potential reduction in anastomotic leak, with no negative oncological consequences.
• Other benefits: improved haemostasis & nerve preservation
• Margins
  • High ant resection: aim for 5cm clearance (& 10 cm of proximal bowel)
  • Low ant resection (if CA <5cm from anal verge): aim for 2cm clearance (fresh) / 1cm - when fixed Lateral pelvic lymph nodal involvement (more Japanese practice; in Western countries, assumption that neoadjuvant therapy will sterilise these nodes)
• Subset of patients may benefit from lateral pelvic lymphadenectomy (LPLD) or modified approach with pelvic autonomic nerve preserving dissection.
• Factors predicting increased risk are:
  • Female
  • Low rectal cancer
  • Involved mesorectal nodes
  • Advanced T stage
  • Poor differentiation
  • LVI High vs low IMA ligation
• No difference in oncological outcomes
• A high ligation may be needed to provide length of conduit as left colic artery is too short to allow descending colon to reach anal canal.
• If marginal artery minimal or absent, sigmoid may be prone to ischaemia.

Quality of life

• Aim to preserve continence, and avoid sexual and urinary disturbance
• Considerations – APR may be needed for:
  • Oncological: Cancer involving or close to sphincter
  • Functional: restorative surgery outcome may be poor that colostomy better QoL.
  • Frailty: potential complications too risky in elderly or frail
• Distal margin
  • For low tumours, a resection margin of 2 cm is recommended, except for poorly differentiated tumours, still 5 cm.
  • In low rectal cancers so long as the margin itself is uninvolved then the risk of recurrence is not increased
• Tumour height
  • By palpation (PR)
• Landmarks
  • Anal verge is perianal skin at intersphincteric groove. Where hair bearing skin commences.
  • Dentate line is junction between columnar and squamous epithelium. Mucosa above usually more slippery than skin of pecten.
• Distal margin
  • Can a clamp or stapler be placed between tumour and dentate line? Colorectal Surgery A Companion to Specialist Surgical Practice 1, page 84
  • Tumour bulk and location
  • Surgical accessibility of pelvis
• Functional quality of anus
  • ?faecal incontinence or flatus continence

Low anterior resection syndrome

• Frequency or urgency of stools, largely due to the fact you have less space to store stool after removing part of the rectum
• Clustering of stools (many bowel movements during a few hours)
• Fecal incontinence (lack of control over bowel movements)
• Constipation for more than a few days, followed by multiple bowel movements a few days later
• Increased gas
• Abdominal pain
• Small risk of urinary and/or sexual function due to nerve damage

Operations

General options

Temporary defunctioning stoma

• Leak rate after rectal cancer surgery is 10 – 28%
• Diverting stoma recommended for all low rectal – low leak rate & fewer clinical leaks.

Laparoscopic vs open

• Both open and laparoscopic approaches can be considered to be appropriate for rectal cancer resection, though laparoscopic surgery may be better in a subset of patients when performed by surgeons with advanced laparoscopic skills.
• Patients that could be considered to be particularly challenging for a laparoscopic approach would be those with low, bulky tumours, particularly in obese, male patients.
• Oncological outcome – AlaCaRT and ACOSOG Z6051 failed to show ‘non-inferiority’ for laparoscopic rectal cancer compared to open.
• Effect of Laparoscopic-Assisted Resection vs Open Resection on Pathological Outcomes in Rectal Cancer The ALaCaRT Randomized Clinical Trial, page 1
• Benefits of laparoscopic: reduced adhesions, incisional hernia and faster return to work.
• Despite method, most important is achieving good quality TME.

Robotic vs laparoscopic

• ROLARR study. No difference in rate of conversion or other outcomes.
• Effect of Robotic-Assisted vs Conventional Laparoscopic Surgery on Risk of Conversion to Open Laparotomy Among Patients Undergoing Resection for Rectal Cancer The ROLARR Randomized Clinical Trial
• Advantages: articulating instruments, high definition allow more precise dissection in narrow male pelvis.
• Disadvantages: substantial cost, lack of training opportunities, increased operating times especially in early stages.

Abdominoperineal resection

• Extra-levator APR recommended for advanced low rectal cancer – need to excise widely at the level of pelvic floor (level of cancer).
• Positioning is important – may need to be prone.

Laparoscopic anterior resection

Alternative approaches:

Papillon/contact radiotherapy

• Considered for exophytic mobile cancers < 3 cm.
• Curative non-op approach for some T1 cancers.
• For frail/elderly patient unfit for major resection.
• Disadvantage – lack of definitive histology and does not treat mesorectum; nodal mets are contraindication
• Can be combined with conventional external beam or CRT.
• Side effect of bleeding – due to angiogenesis and neovascularisation

Transanal

• Indications
  • Superficial T1 cancer, limited to the submucosa
  • No radiographic evidence of metastatic disease to the regional nodes
  • Tumor <3 cm in diameter
  • Well-differentiated histology, no lymphovascular or perineural invasion
  • Mobile, non-fixed
  • Margin clear (>3 mm)
  • Involving <30 percent of the bowel lumen circumference
  • Patient is able to comply with frequent postoperative surveillance
• If has a transanal excision and then adverse histology → proceed to trans-abdominal excision
  • If adverse features on histo, completion surgery has similar cancer-specific survival to upfront major rectal resection.
• Options
  • TEMS (Transanal endoscopic microsurgery)
  • TAMIS (Transanal Minimally Invasive Surgery)
  • ESD
  • Ta-TME
    • Approached through rectotomy from below with an airseal system, followed by purse-string closure of the rectum.

Non-operative approach – ‘watch and wait’

• Low tumour more likely to respond – more accurate target for delivery of radiation; possible difference in behaviour of low rectal compared to mid or upper rectum.
• CCR may not equate to pCR.

Locally advanced

Pelvic multivisceral exenteration

Patterns of recurrence • Central – at previous rectal anastomosis or residual mesorectum. Can extend anteriorly to urogenital structures or posteriorly up to sacral fascia but not bone. • Sacral – when bony invasion present • Lateral – lateral pelvic sidewall, iliac vessels, autonomic nerves, ureter and can invade greater sciatic foramen to sciatic nerve. Most difficult to achieve R0 - poorest prognosis.

Type of clearance

• Total pelvic clearance (TPC) – removal of rectum, sigmoid, bladder, draining lymph nodes, pelvic peritoneum and lower ureters.

  • In males – prostate and seminal vesicles
  • In females – uterus, ovaries, fallopian tubes and part of vagina.
  • End colostomy + ileal conduit

• Central

  • Rectum
  • Female - TAH/BSO/Vagina
  • Male - Prostate/seminal vescivles

• Anterior pelvic clearance (Urogenital)

  • Removal of distal ureters, bladder
  • In males – prostate and seminal vesicles
  • In females – uterus, ovaries, fallopian tubes and vagina.
  • Ileal conduit required.

• Posterior pelvic clearance

  • Sacrum

• Lateral dissection can be done in 3 planes: • A – mesorectal plane (TME) • B – ureteric plane • C – bony plane – lateral to iliac vessels along obturator internus and piriformis

• Perineal reconstruction

  • Omentoplasty to pelvis can be attempted
  • Mesh can be used
  • Pedicled flaps most commonly used:
  • Vertical Rectus abdominis myocutaneous (VRAM) flaps (unilateral with reconstruction of abdominal harvest site often with mesh).
  • Gracilis myocutaneous flaps (bilateral due to limited coverage)
  • Gluteal myocutaneous rotational or advancement flaps (usually bilateral)
  • Inferior gluteal artery perforator flap (usually bilateral)
  • Free flaps considered if pedicled not an option.

Pelvic exenteration lexicon, page 1

Follow up