Decision making for patients with T1 adenocarcinoma of the low rectum, when treatment options are limited to a transanal local excision or abdominoperineal resection, is challenging.
The aim of this study was to develop a contemporary decision analysis to assist patients and clinicians in balancing the goals of maximizing life expectancy and quality of life in this situation.
We constructed a Markov-type microsimulation in open-source software. Recurrence rates and quality-of-life parameters were elicited by systematic literature reviews. Sensitivity analyses were performed on key model parameters.
Our base case for analysis was a 65-year-old man with low-lying T1N0 rectal cancer. We determined the sensitivity of our model for sex, age up to 80, and T stage.
The main outcome measured was quality-adjusted life-years.
In the base case, selecting transanal local excision over abdominoperineal resection resulted in a loss of 0.53 years of life expectancy but a gain of 0.97 quality-adjusted life-years. One-way sensitivity analysis demonstrated a health state utility value threshold for permanent colostomy of 0.93. This value ranged from 0.88 to 1.0 based on tumor recurrence risk. There were no other model sensitivities.
Some model parameter estimates were based on weak data.
In our model, transanal local excision was found to be the preferable approach for most patients. An abdominoperineal resection has a 3.5% longer life expectancy, but this advantage is lost when the quality-of-life reduction reported by stoma patients is weighed in. The minority group in whom abdominoperineal resection is preferred are those who are unwilling to sacrifice 7% of their life expectancy to avoid a permanent stoma. This is estimated to be approximately 25% of all patients. The threshold increases to 12% of life expectancy in high-risk tumors. No other factors are found to be relevant to the decision.
1 Department of Clinical Decision Making and Health Care, University Health Network and Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
2 Department of Colorectal Surgery, Memorial Sloan Kettering Cancer Center, New York, New York
3 Department of Surgery and Institute of Health Policy, Management, and Evaluation, University of Toronto and Keenan Research Centre, Li Ka Shing Knowledge Institute, St Michael’s Hospital, Toronto, Ontario, Canada
Funding/Support: Research support was provided by the American Society of Colon and Rectal Surgeons through a Medical Student Research Initiation Grant. Dr Baxter holds the Cancer Care Ontario Health Services Research Chair. These funding sources played no role in design, conduct, or reporting of this study.
Financial Disclosures: None reported.
Presented at the Gastrointestinal Cancers Symposium, San Francisco, CA, January 21, 2012.
Correspondence: Nancy Baxter, M.D., Ph.D., Division of General Surgery, St Michael’s Hospital, University of Toronto, 30 Bond St, 16CC-40, Toronto ON, M5B 1W8 Canada. E-mail: email@example.com