The ongoing challenge of large anal cancers: prospective long term outcomes of intensity-modulated radiation therapy with concurrent chemotherapy

// Ali Hosni 1 , Kathy Han 1 , Lisa W. Le 2 , Jolie Ringash 1 , James Brierley 1 , Rebecca Wong 1 , Robert Dinniwell 1 , Anthony Brade 1 , Laura A. Dawson 1 , Bernard J. Cummings 1 , Monika K. Krzyzanowska 3 , Eric X. Chen 3 , David Hedley 3 , Jennifer Knox 3 , Alexandra M. Easson 4 , Patricia Lindsay 1 , Tim Craig 1 and John Kim 1 1 Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada 2 Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada 3 Department of Medical Oncology, Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada 4 Department of Surgical Oncology, Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada Correspondence to: John Kim, email: john.kim@rmp.uhn.ca Keywords: anal cancer; chemoradiotherapy; IMRT; pattern of failure; outcomes Received: November 11, 2017      Accepted: February 27, 2018      Published: April 17, 2018 ABSTRACT Purpose: Patterns of failure and long term outcomes were prospectively evaluated following tumor factors-stratified radiation dose for anal/perianal cancer. Methods: Between 2008–2013, patients with anal/perianal squamous cell carcinoma were accrued to an institutional REB-approved prospective study. All patients were treated with image-guided intensity-modulated radiation therapy (IG-IMRT). Radiation dose selection (27–36 Gy for elective target, and 45–63 Gy for gross target) was based on tumor clinico-pathologic features. Chemotherapy regimen was 5-fluorouracil/mitomycin-C (weeks 1&5). Local [LF], regional failure [RF], distant metastasis [DM], overall- [OS], disease-free [DFS], colostomy-free survival [CFS] and late toxicity were analyzed. Results: Overall, 101 patients were evaluated; median follow-up: 56.5 months; 49.5% male; 34.7% T3/4-category, and 35.6% N+. Median radiation dose was 63 Gy. The most common acute grade ≥3 toxicities were skin (41.6%) and hematological (30.7%). Five-year OS, DFS, CFS, LF, RF, DM rates were 83.4%, 75.7%, 74.7, 13.9%, 4.6% and 5% respectively. Five-year LF for patients with T1-2 and T3-4 disease were 0% and 39.2% respectively. All LF ( n = 14, after 63 Gy, in tumors ≥5 cm) were in the high dose volume except one marginal to the high dose volume. All RF ( n = 4) were within elective dose volume except one within the high dose volume. On multivariable analysis, T3/4-category predicted for poor DFS, CFS and OS. The overall late grade ≥3 toxicity was 36.2% (mainly anal [20%]). Conclusions: Individualized radiation dose selection using IG-IMRT resulted in good long term outcomes. However, central failures remain a problem for locally advanced tumors even with high dose radiation (63 Gy/7weeks).