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Original Investigation
April 23, 2020

Factors Associated With Chemoradiation Therapy Interruption and Noncompletion Among Patients With Squamous Cell Anal Carcinoma

Author Affiliations
  • 1Sunnybrook Health Sciences Centre, Division of Medical Oncology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
  • 2Division of Cancer Care and Epidemiology, Queen’s Cancer Research Institute, Kingston, Ontario, Canada
  • 3Division of Medical Oncology, Department of Oncology, Queen’s University, Kingston, Ontario, Canada
  • 4International Credential Evaluation Service, Queen’s, Kingston, Ontario, Canada
  • 5Department of Surgery, Queen’s University, Kingston, Ontario, Canada
  • 6Division of Radiation Oncology, Department of Oncology, Queen’s University, Kingston, Ontario, Canada
JAMA Oncol. Published online April 23, 2020. doi:10.1001/jamaoncol.2020.0809
Key Points

Question  How often do patients with anal cancer experience treatment deviations from planned curative-intent chemoradiation?

Findings  In this population-based cohort study of 1125 patients with anal cancer, treatment interruptions occurred in 262 (23%) and radiation and chemoradiation noncompletion occurred in 199 (18%) and 280 (25%), respectively. Patients who did not complete chemoradiation had a higher risk of requiring salvage surgery, cancer-specific death, and overall death.

Meaning  Quality improvement efforts are needed to optimize treatment continuity and completion.


Importance  Definitive chemoradiation for anal cancer is effective but may be associated with toxic effects, and some patients may not be able to complete the planned treatment. Identifying factors associated with treatment interruption and noncompletion is important to target quality improvement efforts.

Objective  To identify rates of chemoradiation treatment interruption or noncompletion and factors associated with this among patients with anal cancer treated in routine clinical practice.

Design, Setting, and Participants  In this population-based, retrospective cohort study, the Ontario Cancer Registry was used to identify all incident cases of squamous cell anal cancer treated with curative-intent radiation from 2007 to 2015 in Ontario, Canada. Final analysis of data was performed on August 9, 2019.

Exposures  Curative-intent radiation therapy.

Main Outcomes and Measures  Treatment interruption was defined as more than 7 days between fractions of radiation. Radiation completion was defined as receipt of 45 Gy or more and 25 fractions of radiation. Chemoradiation completion was defined as radiation completion and 2 doses of combination chemotherapy. Associations between patient factors and treatment interruption and noncompletion were estimated with log-binomial models. Cox proportional hazard models were used to estimate the association of treatment interruption or noncompletion with all-cause death, cancer-specific death, and the combined outcome of colostomy or death.

Results  Overall, 1125 patients with stage I-III anal cancer were treated with curative-intent radiation. Treatment interruptions occurred in 262 (23%). Radiation and chemoradiation noncompletion occurred in 199 (18%) and 280 (25%), respectively. No associations were found to correlate with an increased risk of treatment interruption. Patients older than 70 years were less likely to complete chemoradiation (risk ratio [RR], 0.60; 95% CI, 0.52-0.70), compared with those younger than 50 years. Patients with a higher number of comorbidities were also less likely to complete chemoradiation (RR, 0.70; 95% CI, 0.51-0.95). Patients who did not complete chemoradiation had a higher risk of requiring salvage abdominoperineal resection (RR, 1.54; 95% CI, 1.03, 2.31), overall death (hazard ratio [HR], 1.54; 95% CI, 1.23-1.92), cancer-specific death (HR, 1.59; 95% CI, 1.14-2.22), and colostomy or death (HR, 1.80; 95% CI: 1.10-2.93). Treatment interruptions longer than 7 days were not associated with death.

Conclusions and Relevance  Many patients undergoing curative-intent chemoradiation for anal cancer experienced treatment interruption or noncompletion. Quality improvement initiatives to optimize treatment continuity and completion are needed.

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