There are two main ways of quantifying survival estimates after cancer diagnosis.
The cohort method, based on the survival experience of cancer patients whose diagnosis occurred many years ago, fails to disclose recent improvements in cancer detection and treatment.
However, period analysis, a recently developed alternative assessment, provides more up-to-date estimates of cancer survival. It exclusively uses survival data from a specific time period, such as a particular year.
Researchers from Heidelberg, Germany, compared survival estimates obtained using period analysis (for the year 1998) and cohort analysis (for patients diagnosed between 1978 and 1993).
Data were obtained from the US population-based cancer registries.
The team found that period analysis estimates of 5-year, 10-year, 15-year, and 20-year relative survival rates for all types of cancer were 63%, 57%, 53%, and 51%, respectively.
These estimates were 1%, 7%, 11%, and 11% higher, respectively, than corresponding estimates using cohort-based survival analysis.
Furthermore, period analysis found 20-year relative survival rates were close to 90% for thyroid and testicular cancer, exceeded 80% for melanomas and prostate cancer, were 80% for endometrial cancer, and almost 70% for bladder cancer and Hodgkin's disease.
A 20-year relative survival rate of 65% was estimated for breast cancer, of 60% for cervical cancer, and of about 50% for colorectal, ovarian, and kidney cancer.
|Relative survival rate estimates up to 11% greater using period analysis.|
Professor Hermann Brenner concluded, "The provision of up-to-date long-term survival rates is not merely an academic exercise.
"It could help to prevent clinicians and their patients from undue discouragement or depression by outdated and often overly pessimistic survival expectations.
"Timely detection of improvements in long-term survival rates also adds to the value of cancer surveillance as a basis for appropriate public-health decisions."