title: Intensity-Modulated Radiotherapy (IMRT) vs Helical Tomotherapy (HT) in Concurrent Chemoradiotherapy (CRT) for Patients with Anal Canal Carcinoma (ACC): an analysis of dose distribution and toxicities.
abstract: OBJECTIVE
  Intensity-modulated radiotherapy (IMRT) and helical tomotherapy (HT) have been adopted for radiotherapy treatment of anal canal carcinoma (ACC) due to better conformality, dose homogeneity and normal-tissue sparing compared to 3D-CRT. To date, only one published study compares dosimetric parameters of IMRT vs HT in ACC, but there are no published data comparing toxicities. Our objectives were to compare dosimetry and toxicities between these modalities.
  
  
  METHODS
  This is a retrospective study of 35 ACC patients treated with radical chemoradiotherapy at two tertiary cancer institutions from 2008-2010. The use of IMRT vs HT was primarily based on center availability. The majority of patients received fluorouracil (5-FU) and 1-2 cycles of mitomycin C (MMC); 2 received 5-FU and cisplatin. Primary tumor and elective nodes were prescribed to ≥54Gy and ≥45Gy, respectively. Patients were grouped into two cohorts: IMRT vs HT. The primary endpoint was a dosimetric comparison between the cohorts; the secondary endpoint was comparison of toxicities.
  
  
  RESULTS
  18 patients were treated with IMRT and 17 with HT. Most IMRT patients received 5-FU and 1 MMC cycle, while most HT patients received 2 MMC cycles (p<0.01), based on center policy. HT achieved more homogenous coverage of the primary tumor (HT homogeneity and uniformity index 0.14 and 1.02 vs 0.29 and 1.06 for IMRT, p=0.01 and p<0.01). Elective nodal coverage did not differ. IMRT achieved better bladder, femoral head and peritoneal space sparing (V30 and V40, p ≤ 0.01), and lower mean skin dose (p<0.01). HT delivered lower bone marrow (V10, p<0.01) and external genitalia dose (V20 and V30, p<0.01). Grade 2+ hematological and non-hematological toxicities were similar. Febrile neutropenia and unscheduled treatment breaks did not differ (both p=0.13), nor did 3-year overall and disease-free survival (p=0.13, p=0.68).
  
  
  CONCLUSIONS
  Chemoradiotherapy treatment of ACC using IMRT vs HT results in differences in dose homogenity and normal-tissue sparing, but no significant differences in toxicities.
authors.affiliation: Department Oncology, Division of Radiation Oncology, University of Calgary, Tom Baker Cancer Center Calgary, 1331- 29th Street NW, Calgary, Alberta, T2N4N2, Canada. rosanna.yeung@albertahealthservices.ca.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Yeung
authors.affiliation: Department of Surgery, University of Calgary, Foothills Medical Center, North Tower 10th Floor,1403- 29th Street NW, Calgary, Alberta, T2N 2T9, Canada. yarrow.mcconnell@gmail.com.
authors.forename: Yarrow
authors.initials: Y
authors.lastname: McConnell
authors.affiliation: Department of Oncology, Division of Medical Physics, Cross Cancer Institute, University of Alberta, 11560 University Ave NW, Edmonton, Alberta, T6G 1Z2, Canada. heather.warkentin@albertahealthservices.ca.
authors.forename: Heather
authors.initials: H
authors.lastname: Warkentin
authors.affiliation: Department Oncology, Division of Radiation Oncology, University of Calgary, Tom Baker Cancer Center Calgary, 1331- 29th Street NW, Calgary, Alberta, T2N4N2, Canada. darren.graham2@albertahealthservices.ca.
authors.forename: Darren
authors.initials: D
authors.lastname: Graham
authors.affiliation: Department of Oncology, Division of Medical Physics, Cross Cancer Institute, University of Alberta, 11560 University Ave NW, Edmonton, Alberta, T6G 1Z2, Canada. brad.warkentin@albertahealthservices.ca.
authors.forename: Brad
authors.initials: B
authors.lastname: Warkentin
authors.affiliation: Department of Oncology, Division of Radiation Oncology, Cross Cancer Institute, University of Alberta, 11560 University Ave NW, Edmonton, Alberta, T6G 1Z2, Canada. kurian.joseph@albertahealthservices.ca.
authors.forename: Kurian
authors.initials: K
authors.lastname: Joseph
authors.affiliation: Department Oncology, Division of Radiation Oncology, University of Calgary, Tom Baker Cancer Center Calgary, 1331- 29th Street NW, Calgary, Alberta, T2N4N2, Canada. corinne.doll@albertahealthservices.ca.
authors.forename: Corinne M
authors.initials: CM
authors.lastname: Doll
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects*; D001005:Anus Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D059248:Chemoradiotherapy / Q000009:adverse effects*; D002945:Cisplatin / Q000008:administration & dosage; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D005500:Follow-Up Studies; D005767:Gastrointestinal Diseases / Q000175:diagnosis / Q000209:etiology; D006402:Hematologic Diseases / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016685:Mitomycin / Q000008:administration & dosage; D009367:Neoplasm Staging; D011379:Prognosis; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D012871:Skin Diseases / Q000175:diagnosis / Q000209:etiology; D015996:Survival Rate
chemical_list: D016685:Mitomycin; D002945:Cisplatin; D005472:Fluorouracil