A new study explored risk factors for chemoradiation treatment interruption or noncompletion among patients with anal cancer.
“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,” explained the study authors.
The researchers conducted a population-based, retrospective cohort study using the Ontario Cancer Registry to identify incident squamous cell anal cancer cases treated with curative-intent radiation from 2007 through 2015. The exposure was curative-intent radiation therapy. Treatment interruption was defined as more than seven days between fractions of radiation; radiation completion was defined as receipt of 45 Gy or more and 25 fractions of radiation; and chemoradiation completion was defined as radiation completion and two doses of combination chemotherapy. Log-binomial models were used to analyze the relationships between patient factors and treatment interruption and noncompletion, and Cox proportional hazard models were used to evaluate the correlation of treatment interruption or noncompletion with all-cause death, cancer-specific death, and the combined outcome of colostomy or death.
Final analysis included 1,125 patients with stage I to III anal cancer who received curative-intent radiation. Just under a quarter of patients (n=262, 23%) experienced treatment interruptions; 199 patients (18%) had radiation noncompletion, and 280 (25%) had chemoradiation noncompletion. There were no risk factors identified for treatment interruption. Patients were less likely to complete chemoradiation if they were age older than 70 years versus younger than 50 years (risk ratio [RR]=0.60; 95% confidence interval [CI], 0.52 to 0.70) and had a higher number of comorbidities (RR=0.70; 95% CI, 0.51 to 0.95). Salvage abdominoperineal resection risk was also higher among patients who did not complete chemoradiation (RR=1.54; 95% CI, 1.03 to 2.31), as were risks for overall death (hazard ratio [HR]=1.54; 95% CI, 1.23 to 1.92), cancer-specific death (HR=1.59; 95% CI, 1.14 to 2.22), and colostomy or death (HR=1.80; 95% CI, 1.10 to 2.93). There was no correlation between treatment interruptions longer than seven days and death.
The study was published in JAMA Oncology.
“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,” the study authors summarized.