Radiation Oncology/Anal canal/RT Technique

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Anal Cancer RT Technique

RT dose escalation[edit | edit source]

  • RTOG 92-08 (1992-6) -- split course 59.6 Gy
    • Preliminary results: 1996 PMID 9166533 -- "Dose escalation in chemoradiation for anal cancer: preliminary results of RTOG 92-08." (John M, Cancer J Sci Am. 1996 Jul-Aug;2(4):205-11.)
    • Phase II, dose-escalation, split course RT. 47 patients, cancer >= 2cm. RT 59.6 Gy split course with 2-week break. Initial pts treated 1992-3. Comparison with RTOG 87-04
    • After unexpectedly high rates of colostomy (23%), treatment break was eliminated. 20 additional patients were treated (1995-6). 9 completed protocol, 9 required treatment break anyway. Median RT dose 41 Gy (Abstract ASTRO 1997). Colostomy rate 11%
    • Conclusion: No improvement in local control in split-course RT. Suggest continuous RT, but may have to accept higher acute toxicity
    • 10-years: 2008 PMID 18472363 -- "Evaluation of planned treatment breaks during radiation therapy for anal cancer: update of RTOG 92-08." (Konski A, Int J Radiat Oncol Biol Phys. 2008 Sep 1;72(1):114-8.)
      • DFS: 5-yr 53%, 8-yr 34% (break); vs 80%/63% (no break). Colostomy-free survival: 58%/34% vs 75%/63%.
      • Pts treated with mandatory break had worse OS, DFS, and CFS compared with 87-04, whereas pts treated with no mandatory break were similar to historical controls. However, the trial was small and not powered to compare efficacy endpoints.

Segmental boost technique[edit | edit source]

Uses wide AP field, narrow PA field, and angled photon inguinal fields (matched to the divergence of the PA field). Single isocenter technique.

  • Yale, 2004
    • 2004 PMID 15275740 -- "Improved treatment of pelvis and inguinal nodes using modified segmental boost technique: dosimetric evaluation." (Moran MS, Int J Radiat Oncol Biol Phys. 2004 Aug 1;59(5):1523-30.)
    • 2010 PMID 19596174 -- "Clinical utility of the modified segmental boost technique for treatment of the pelvis and inguinal nodes." (Moran MS, Int J Radiat Oncol Biol Phys. 2010 Mar 15;76(4):1026-36.)

Inguinal node photon boost[edit | edit source]

  • Indianapolis, 2001 PMID 11295207 — "A technique for inguinal node boost using photon fields defined by asymmetric collimator jaws." Dittmer PH et al. Radiother Oncol. 2001 Apr;59(1):61-4.
    • Treats the pelvis using PA field, pelvis + inguinals using AP field, plus a further boost to the inguinals using AP photons with asymmetric collimator jaws (using the same isocenter).

"Diamond" technique[edit | edit source]

  • McGill
    • 2007 PMID 17276620 — "Conformal therapy improves the therapeutic index of patients with anal canal cancer treated with combined chemotherapy and external beam radiotherapy." (Vuong T, Int J Radiat Oncol Biol Phys. 2007 Apr 1;67(5):1394-400.)
    • 2003 PMID 12788191 — "Contribution of conformal therapy in the treatment of anal canal carcinoma with combined chemotherapy and radiotherapy: results of a phase II study." (Vuong T, Int J Radiat Oncol Biol Phys. 2003 Jul 1;56(3):823-31.)

IMRT[edit | edit source]

  • Multicenter; 2007 (2000-2006) PMID 17925552 -- "Concurrent chemotherapy and intensity-modulated radiation therapy for anal canal cancer patients: a multicenter experience." (Salama JK, J Clin Oncol. 2007 Oct 10;25(29):4581-6.
    • Prospective. 53 patients (62% T-2, 67% N0, 15% HIV+) treated with concurrent chemo (5-FU/mitomycin, or FU alone) and RT. Primary sites and involved LN median 51.5 Gy, pelvis and inguinal LN median 45 Gy. Median F/U 14 months
    • Toxicity: Grade 3 GI 15%, dermatologic 38%; Grade 4 leukopenia 30%, neutropenia 34%. Treatment break in 41%, median 4 days
    • Conclusion: Effective, and compares favorably with historical standards
  • France (Montpellier), 2007 PMID 18005443 — "Optimal organ-sparing intensity-modulated radiation therapy (IMRT) regimen for the treatment of locally advanced anal canal carcinoma: a comparison of conventional and IMRT plans." (Menkarios C, Radiat Oncol. 2007 Nov 15;2:41.)
    • Treatment planning study. Compared: 1) AP/PA + 3D-CRT boost, 2) Pelvic IMRT + 3D-CRT boost, 3) Pelvic IMRT + IMRT boost, 4) IMRT with simultaneous integrated boost.
    • Conclusion: Compared to conventional plan, all IMRT plans reduced the dose to bowel, bladder, genitalia, and bone marrow.
  • U Chicago, 2005 PMID 16168830 "Intensity-modulated radiation therapy (IMRT) in the treatment of anal cancer: toxicity and clinical outcome." Milano MT et al. Int J Radiat Oncol Biol Phys. 2005 Oct 1;63(2):354-61.
    • IMRT remarkably well tolerated, with minimal toxicity.

Contouring[edit | edit source]

  • RTOG Atlas
    • RTOG Anorectal Contouring Guidelines
    • 2009 PMID 19117696 -- "Elective clinical target volumes for conformal therapy in anorectal cancer: a radiation therapy oncology group consensus panel contouring atlas." (Myerson RJ, Int J Radiat Oncol Biol Phys. 2009 Jul 1;74(3):824-30. Epub 2008 Dec 29.)