Abstract
PurposeOur purpose was to describe the patterns and predictors of treatment failure in patients receiving definitive chemoradiation therapy (CRT) for anal squamous cell carcinoma (ASCC), delivered using intensity modulated radiation therapy (IMRT).Methods and MaterialsOur study was a retrospective cohort analysis of consecutive patients treated with curative intent for ASCC using CRT delivered with a standardized IMRT technique in 5 UK cancer centers. Patients were included from the start of UK IMRT guidance from February 2013 to October 31, 2017. Collected data included baseline demographics, treatment details, tumor control, sites of relapse, and overall survival. Statistical analysis to calculate outcomes and predictive factors for outcome measures were performed using SPSS and R.ResultsThe medical records of 385 consecutive patients were analyzed. Median follow-up was 24.0 months. Within 6 months of completing CRT, 86.7% of patients achieved a complete response. Three-year disease-free survival and overall survival were 75.6% and 85.6%, respectively. Of all relapses, 83.4% occurred at the site of primary disease. There were 2 isolated relapses in regional nodes not involved at outset. Predictive factors for cancer recurrence included male sex, high N-stage, and failure to complete radiation therapy as planned.ConclusionsThe treatment results compare favorably to published outcomes from similar cohorts using 3-dimensional conformal CRT. The observed patterns of failure support the current UK IMRT voluming guidelines and dose levels, highlighting our prophylactic nodal dose as sufficient to prevent isolated regional relapse in uninvolved nodes. Further investigation of strategies to optimize CR should remain a priority in ASCC because the site of primary disease remains the overwhelming site of relapse.
Highlights
IntroductionAnal squamous cell carcinoma (ASCC) is an uncommon malignancy, with an annual incidence of approximately 8500 in the United States and 1500 in the United Kingdom.[1,2,3,4] Chemoradiation therapy (CRT) with concurrent mitomycin-c and 5-fluorouracil has been established as the standard of care after 6 large international trials.[5,6,7,8,9,10,11,12]In the last decade, there has been increasing use of intensity modulated radiation therapy (IMRT).[13,14,15,16,17] Various protocols have been developed internationally, with differences in doses, volumes, and constraints.[18,19,20,21] The UK IMRT guidance was derived from the principles of the UK ACT2 phase 3 trial.[21]
The UK intensity modulated radiation therapy (IMRT) guidance was derived from the principles of the UK ACT2 phase 3 trial.[21]
Medical records were retrospectively reviewed for patients with anal canal and anal margin squamous cell carcinoma who underwent definitive radiation therapy (RT) using an IMRT technique from February 2013 to February 2018 in 5 UK Cancer Centres: Oxford Cancer and Haematology Centre, Leeds Cancer Centre, Queen Elizabeth Hospital, Birmingham; Sussex Cancer Centre, Brighton and Velindre Cancer Centre, Cardiff
Summary
Anal squamous cell carcinoma (ASCC) is an uncommon malignancy, with an annual incidence of approximately 8500 in the United States and 1500 in the United Kingdom.[1,2,3,4] Chemoradiation therapy (CRT) with concurrent mitomycin-c and 5-fluorouracil has been established as the standard of care after 6 large international trials.[5,6,7,8,9,10,11,12]In the last decade, there has been increasing use of intensity modulated radiation therapy (IMRT).[13,14,15,16,17] Various protocols have been developed internationally, with differences in doses, volumes, and constraints.[18,19,20,21] The UK IMRT guidance was derived from the principles of the UK ACT2 phase 3 trial.[21]. There have been some small iterations; the guidance remains very similar to that at conception in February 2013
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