A recently published Statistics Canada paper shows that the prognosis for many Canadian cancer patients improves, sometimes substantially, after surviving for a year or more after diagnosis.
The Conditional Survival Analyses Across Cancer Sites paper is the first of its kind in Canada to look at survival patterns for 26 different cancers at each year over the first five years after diagnosis. It provides information on relative survival rates, which measure the likelihood of a cancer patient surviving for five years compared to the likelihood of survival for the general population.
“This looks at survival data in a new way. By examining survival rates across many cancers at different time periods we see where prognosis is and is not improving over time since diagnosis. Colon cancer patients for example have a 63% relative 5-year survival at the time of diagnosis but two years later this has increased to 85%, and at five years it is 97%,” says Dr. Heather Bryant, Vice-President of Cancer Control with the Partnership and study co-author. “Other cancers like breast have higher relative 5-year survival at diagnosis at 88%, but it stays relatively flat at 93% in five years.”
“This is important information because not only does it provide updated prognoses for those who have already survived for one or more years with a specific type of cancer, but the information also helps us identify where we can make improvements. For some cancers it points to the need for better screening programs to identify cancers earlier, for others to help researchers and healthcare providers understand what the knowledge gaps are in terms of follow up care and monitoring of their patients with cancer,” added Dr. Bryant.
The data for the paper was obtained by linking the Canadian Cancer Registry to the Canadian Vital Statistics Death Database. The researchers analyzed data involving patients across the country and 26 different kinds of cancer diagnosed between 2004 and 2006. The estimates are based on the average survival time for large groups of patients, rather than an individual’s prognosis.
The Partnership’s Manager of Analytics and Senior Biostatistician and co-author Gina Lockwood notes “this is the first time that Canadian data has been used to predict conditional survival ratios for the most common cancers. These statistics help us understand how well we are detecting, diagnosing and treating cancers in Canada.”
Larry F. Ellison, Senior Analyst/Epidemiologist in the Health Statistics Division at Statistics Canada and Lorraine Shack of Alberta Health Services/University of Calgary were also co-authors for the paper. For more information and to read the paper see the Health Reports section on the Statistics Canada website.