Highlights
- People diagnosed with colorectal cancer have a greatly improved chance of surviving another 5 years as the time since diagnosis increases.
- Conditional relative survival statistics provide a more realistic and optimistic prognosis for people still alive several years after diagnosis.
The longer someone lives after being diagnosed with colorectal cancer, the greater his or her chances are of continuing to survive the disease. For people diagnosed with colorectal cancer in 2006–2010, the probability of surviving 5 years compared to people of the same age and sex in the general population (i.e., their 5-year relative survival) was 66%. Conditional relative survival rates – a slightly different survival measure – show that people who lived for 2 years after their diagnosis had an 81% chance of surviving another 5 years compared to the general population. The conditional survival continued to increase for people who lived 5 years after being diagnosed, making their chances of living another 5 years (for a total of 10 after diagnosis) 91%. In other words, by the time people with colorectal cancer have lived for 5 years beyond their diagnosis, their disease has only a small impact on their 5-year life expectancy.
While relative survival ratios are the statistic most often used to estimate the average survival of people with colorectal cancer, they do not reflect the survival experience of many people with this disease. Relative survival estimates a person’s prognosis at the time of diagnosis compared to people of the same age and sex in the general population, which may be misleading for some people because the risk of dying from colorectal cancer is greatest soon after being diagnosed with the disease—within the first few months and then within the first 3 years. Conditional relative survival statistics, on the other hand, estimate a person’s prognosis at various time points after being diagnosed instead of only at the time of diagnosis. By describing how survival changes throughout the cancer experience, conditional relative survival provides a more informative and optimistic outlook for colorectal cancer patients as more time passes after their diagnosis.[1]
Stage at diagnosis is one of the most important determinants of survival for colorectal cancer. Screening can detect the disease at an earlier, asymptomatic stage when treatment is more likely to be effective. When caught early, there is a 90% chance that people with colorectal cancer will be cured, compared with only 12% if the disease is found at an advanced stage.[2] To help detect colorectal cancer early, Cancer Care Ontario launched ColonCancerCheck in April 2008, Canada’s first organized, province-wide, population-based colorectal cancer screening program. Overall survival for colorectal cancer has improved in Ontario over the past 10 years, which is partly related to advances in detection and treatment.[3] As participation in Ontario’s screening program increases, further improvements in survival are expected, thanks to more cancers being diagnosed earlier.
ColonCancerCheck recommends that people aged 50–74 without a family history of colorectal cancer get screened for the disease every 2 years using the fecal occult blood test (FOBT), with colonoscopy as a follow-up after an abnormal FOBT result. For people who are at increased risk of colorectal cancer due to family history of the disease (1 or more first-degree relatives—parent, sibling or child—with colorectal cancer), ColonCancerCheck recommends colonoscopy beginning at age 50, or 10 years younger than the age at which their relative was diagnosed, whichever occurs first.