Role of radiation in carcinoma rectum and colon

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Role of radiation in carcinoma rectum and colon

  1. 1. Role of radiation in carcinoma rectum and colon Dr Bharti Devnani Moderator:- Dr Manoj K.Sharma
  2. 2. RT for rectal cancer was first introduced in the 1980s, in an attempt to decrease rates of local recurrence in patients with locally advanced rectal cancer. One of the first RCTs to show decrease in local recurrence with the use of adjuvant therapy was published in 1985 by the Gastrointestinal Tumor Study Group (USA) In the United States, the first official recommendation for the use of adjuvant chemoradiation in patients with rectal cancer came from the National Institutes of Health (NIH) consensus statement, published in 1990. Set the standard of care for patients with stage II and III.
  3. 3. Although postoperative regimens were being optimized in 1990s within United States, around the same period investigators in Europe were exploring the potential benefits of treatment given in the preoperative setting (Neoadjuvant RT). Two different regimens of neoadjuvant RT were being assessed: long course RT, used mainly in the United States; and short course RT, used mainly in Europe
  4. 4. Benefit with addition of preop RT to Surgery
  5. 5. Pre-op RT v/s chemoradiation
  6. 6. Preop CTRT v/s postop CTRT
  7. 7. German Rectal Cancer Study N Eng J Med 351;17 october 21, 2004
  8. 8. T3/T4/N+ N=421 Preop CT+RT 50.4 Gy/28# with CI 5- FU1000mg/m2(D1-D5) in 1st &5th wk foll by Sx at 6 wks and 4 cycles of adjuvant chemo N=402 Post op setting –additional boost of 5.4 Gy
  9. 9. Local recurrence 6% v/s 13% (p=0.006) NO OS benefit
  10. 10. Rate of sphincter preservation -39% v/s 19%-more than double
  11. 11. Acute and long term toxicities are less Arm No of pts Any grade 3-4 acute toxicity Grade 3-4 acute diarrhea Any grade 3-4 long term toxicity Stricture at anastomotic site Preop CT RT 405 27% 12% 14% 4% Postop CT RT 394 40% 18% 24% 12% ‘p’ value 0.001 0.04 0.001 0.003 Preop CTRT improved local control with reduced toxicity and more sphincter preservation rate
  12. 12. No OS benefitBenefit in local control persisted at 11 yrs Update of german trial
  13. 13. ADVANTAGES OF PRE-OP CHEMORADIATION
  14. 14. 1.Tumor tissue is better oxygenated so irradiation is more effective 2.Downstaging of the tumor leads to:- More curative surgery Conversion of APR to sphinctor preservation (rate is doubled 39% v/s 19% in german study ) 3.Local recurrence decreased (6% v/s 13 % with a ‘p’ value of 0.006) 4. Compliance is better (Better tolerated)
  15. 15. With postop RT the soft tissues of the perineum are at risk, for involvement after an APR because of surgical manipulation and, need to be irradiated with acute skin toxicity.
  16. 16. With postop RT, normal bowel is moved into the pelvis for the anastomosis after a LAR & is irradiated leading to late toxicity. In the preoperative setting much of the irradiated bowel is removed with the surgical specimen and therefore is not at risk for producing late bowel injury. Avoidance of radiation to the neorectum.
  17. 17. Reduction in the risk of tumor seeding during surgery. Avoiding Tt. delays due to prolonged post-op healing. Higher pCR rates
  18. 18. Disadvantages  Overtreatment of early stage tumors (18 % in german study)  Delay in surgery  Wound healing problem
  19. 19. Indications of RT
  20. 20. Preoperative RT For stage II-III resectable disease Definitive treatment Unresectable/unfit for surgery Small rectal cancer Palliative radiation Advanced disease For metastatic sites(liver SBRT etc) IORT Incomplete resection Residual/recurrent disease
  21. 21. Preoperative setting Preop CT RT for Stage II –III disease Stage II (T3 and T4 disease) & Stage III that is (any T with Nodal positivity)
  22. 22. Postop Radiation
  23. 23. Synchronus metastasis
  24. 24. Techniques of Radiation
  25. 25. RT portals 1. Whole pelvic field: PA/AP  Lateral border - 1.5 cm lateral to the widest bony margin of the true pelvic walls  Distal border: 3 cm below the primary tumor or at the inferior aspect of obturator foramina, whichever is the most inferior  Superior border: L5-S1 junction
  26. 26. RT portals B: Lateral  Posterior border: 1 to 1.5 cm behind the anterior bony sacral margin  Anterior border: 1. T3 disease: post margin of the symphysis pubis(to treat only the internal iliac nodes) 2. T4 disease: ant margin of the symphysis pubis (to include the external iliac nodes) T3 T4
  27. 27. RT portals 3. After an abdominoperineal resection: Wire the perineal scar and create a 1.5 cm margin beyond the wire fields. Bolus the perineal scar every other day to bring the dose to 100%
  28. 28. Methods to Decrease Radiation Toxicity RT technique Physical maneuvers Sequencing of RT and surgery Surgical maneuvers in patients treated postoperatively Pharmacological approaches and radio protectors
  29. 29. RT technique
  30. 30.  High-energy (>6 MV) linear accelerators.  All fields should be treated each day.  Shaped blocks and wedges on the lateral fields.  A wire at the perineal scar after APR help to guide field design.  Small bowel contrast used to help Shielding of small bowel.  Rectal contrast :-Barium sulfate is injected with a Foley catheter.  Bladder protocol  Computerised radiation dosimetery
  31. 31.  Multiple-field technique (3 or 4 field )  3 field (PA + lat)rather than 4 field is preferred in:-  In males if the genitalia are in the treatment field  Colostomy is present  For perineal scar coverage separate perineal field should not be used(should be included in the pelvic radiation field)
  32. 32. Physical Maneuvers
  33. 33. Prone position with abdominal wall compression and bladder distension Treatment in the prone position without abdominal wall compression was not consistently effective in displacing small bowel and in some patients, most commonly obese, the volume of small bowel increased.
  34. 34. Prone position with Abd wall compression and bladder distension Immobilization molds (belly boards) Shanahan and colleagues reported that the combination of the prone position and immobilization molds decreased the mean small-bowel volume in the radiation field by 66% compared with patients treated in the supine position without the immobilization mold.
  35. 35. Sequencing of RT and surgery
  36. 36. Preop CTRT preferred :-  Less acute and chronic toxicities  Mobile small bowel  Coverage of perinium not required  Strictures at the anastomotic site reduced
  37. 37. Surgical maneuvers in patients treated postoperatively
  38. 38.  Placing surgical clips  Placement of an absorbable Dexon or Vicryl mesh temporarily remove the small bowel from the pelvis.  Other methods:-  Construction of omental pedical flap  Small bowel displacement prosthesis reconstruction of pelvic floor  Retroversion of uterus
  39. 39. Pharmacological approaches and radio protectors
  40. 40.  Sucralfate enemas  Olsalazine  Mesalazine All of these trials have been negative Final Results of a Randomized Phase III Trial of Chemoradiation treatment Amifostine in Patients with Colorectal Cancer: Clinical Radiation Oncology Hellenic Group By Antonadou et al Amifostine significantly reduced the incidence of grade 2 gastrointenstinal toxicity. There was no evidence of compromised treatment efficacy.
  41. 41. Advantages with conformal techniques
  42. 42.  Ability to plan and localise the target and normal tissues.  Less toxicites  Obtaining DVH  More conformal plans
  43. 43. Target delineation as per RTOG contouring guidelines
  44. 44. Sites of recurrence
  45. 45. Short course v/s long course RT
  46. 46. Results of Polish trial ARM SC LC pCR(%) 1 16 Radial margin positivity(%) 13 4 Sphinctor preservation(%) 58 NS 61 Early radiation toxicity 3 18 LC DFS & late toxicity NS
  47. 47. 326 patients radomaly assigned Long course RT 50.4 Gy @ 1.8 in 5.5 wks with CI 5-FU foll by Sx at 4-6 wks & 4 cycles adj CT Short course RT RT 5x5 in 1 wk foll by early Sx & 6 cycle adj CT
  48. 48. No difference in OS Locoregional recurrence No stastically significant difference but • Favouring long course •pCR better with long course •Long course better for distal tumor (12.5% v/s 0%)
  49. 49. Endocavitory Radiation (Papillon technique) Papillon is the name of the French professor from Lyon who popularised this technique.
  50. 50. Selection criteria Early noninvasive tumors For more advanced tumors (T2,T3) used in conjunction with BT or XRT G1-G2 tumors Without deep ulceration With in 10 cm from dentate line Tumors with diameter <3 cm (size of the proctoscope is 3 cm)
  51. 51. Method  Anus is dilated  4-cm proctoscope is introduced.  low-energy x-ray (50-kV x-rays) unit is placed through the scope against the tumor.  Delivered at 30 Gy per fraction in three or four fractions over 1 month.
  52. 52. Local control rates of 76% can be achieved at 10 years after treatment with this technique
  53. 53. Lyon technique Créteil technique Template technique
  54. 54. Intra-operative Radiotherapy (IORT) IOERT HDR-BT
  55. 55. Intra-operative Radiotherapy (IORT) Tumor site accessible to IORT applicator Locally advanced tumor Recurrent tumor Tumor not resected/Gross residual tumor Positive surgical margin Critical structures (dose limiting) are excluded
  56. 56. Advantages with IORT Radiation can be delivered at the time of surgery to the site with highest risk of local failure Normal tissue sparing Very useful in recurrent setting
  57. 57. Dose Ro resection:-7.5-10 Gy R1 resection:-10-12.5 Gy R2 resection:-15-20 Gy
  58. 58. Chances of local failure decreased In margin negative cases from 15% 11% After R1 resection 83% 32% After R2 resection 83% 43%
  59. 59. Side effects and managment
  60. 60. Early complications  Diarrhea  Increased bowel frequency  Dysuria  Acute proctitis  Malabsorption of fat,carbohydrate,protein and bile salts Mechanism:- depletion of actively dividing cells
  61. 61. Late complications Small bowel obstruction Bleeding Persistent diarrhea Scrotal/perineal tenderness Urinary incontinence Stricture Second cancer
  62. 62. Role of RT in colon cancer Treatment recommendations should be made on a case-by-case basis with existing data in setting of an informed consent. Adj tumor bed RT with concurrent 5-FU based chemo should be considered for pts with tumors (a) invading adjoining structures (b) those complicated by perforation or fistula (c) Incomplete resection is performed
  63. 63. THANK YOU

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