Anal Cancer Treatment Completion Rates Suboptimal

Author: By Lynda Williams, Senior medwireNews Reporter 

medwireNews: Canadian research suggests that up to a quarter of patients with stage I–III squamous cell anal carcinoma do not complete their treatment, increasing their risk of salvage surgery and death. 

“Quality improvement initiatives to optimize treatment, treatment continuity, and completion are needed”, the investigators write in JAMA Oncology, after reviewing data from the Ontario Cancer Registry for 1125 patients who were scheduled to undergo radiation with curative intent between 2007 and 2015 at one of 16 centres.

Overall, 23% of the patients experienced a treatment interruption, defined as at least 7 days between two fractions of radiation, report Sunil Patel, from Queen’s Cancer Research Institute in Kingston, Ontario, and co-authors. 

Patients received a median 54 Gy of radiotherapy over a median of 46 days, with 82% receiving at least 25 fractions and 84% receiving more than 45 Gy; both factors were required for completion of radiotherapy and this was achieved in 82%. 

In addition, 76% of 1002 patients received at least two doses of concurrent chemotherapy, the criteria for chemoradiotherapy completion. 

Of concern, the researchers identified considerable variation in the rates between cancer centres, with radiotherapy interruption ranging from 9% to 55%, radiation completion from 66% to 93%, and chemoradiotherapy completion from 17% to 80%. 

Nevertheless, rates of chemoradiotherapy completion significantly increased over time, from 55% in 2007–2009 to 72% in 2013–2015, the team notes. 

There were no significant predictors of treatment interruption but completion of radiotherapy and chemoradiotherapy were significantly less likely in patients aged over 70 years than those aged less than 50 years (relative risk [RR]=0.86 and 0.60, respectively), after adjusting for age, sex, stage, comorbidity and HIV status. 

In addition, patients with comorbidity were significantly less likely to complete chemoradiotherapy than those without (RR=0.70), report Sunil Patel et al. 

Five-year overall survival was significantly better among patients who completed radiotherapy than those who did not (73 vs 61%) and among those who did versus did not complete concurrent chemotherapy (77 vs 60%). 

After adjusting for potential confounders, the researchers found that incomplete chemoradiotherapy was a significant predictor of need for salvage abdominoperineal resection (RR=1.54), as well as a significant risk factor for colostomy or death (hazard ratio [HR]=1.80), cancer-specific death (HR=1.59) and overall death (HR=1.54). 

Patients who did not complete radiotherapy also had an increased risk of the need for salvage surgery and a greater risk of colostomy or death than those who completed treatment, although these endpoints did not reach statistical significance. Nevertheless, incomplete radiation treatment was associated with a significant risk for cancer-specific and overall death, with HRs of 1.90 and 1.47, respectively. 

“These findings highlight the need for quality improvement efforts to support elderly and comorbid patients during treatment, and to ensure consistency of radiation provision across treatment facilities”, the authors conclude.

“In addition, it would be important to investigate the specific needs of these patient populations that are resulting in treatment protocol deviations.” 

Reference  

Raphael MJ, Ko G, Booth CM, et al. Factors associated with chemoradiation therapy interruption and noncompletion among patients with squamous cell anal carcinoma. JAMA Oncol; Advance online publication 23 April 2020. doi:10.1001/jamaoncol.2020.0809