SEER now provides age standard adult cancer populations (ages 15+) to calculate age standardized survival. Age-standardized survival is used to compare survival across time or different cancer populations with different age distributions. The standards provided are the International Cancer Survival Standard (ICSS) derived in Corazziari et al. (2004) for three broad groups of cancer sites with similar patterns of incidence by age. The idea is that by using the appropriate standard, the age-standardized survival would be similar to the raw (un-weighted) survival.
Standard Populations for Survival
The three standards can be generally described as:
- International Cancer Survival Standard (ICSS) 1 - For cancer sites with increasing incidence by age (most cancer sites)
- International Cancer Survival Standard (ICSS) 2 - For cancer sites with broadly constant incidence by age
- International Cancer Survival Standard (ICSS) 3 - For cancer sites that mainly affect young adults
Cancer Site for Which Each of the Three International Cancer Survival Standards (ICSS) Apply*
|ICSS Standard||Cancer Sites|
|1||Lip, tongue, salivary glands, oral cavity, oropharynx, hypopharynx, head & neck, oesophagus, stomach, small intestine, colon, rectum, liver, biliary tract, pancreas, nasal cavities, larynx, lung, pleura, breast, corpus uteri, ovary, vagina & vulva, penis, bladder, kidney, choroid melanoma, non-Hodgkin lymphomas, multiple myeloma, chronic lymphatic leukaemia, acute myeloid leukaemia, chronic myeloid leukaemia, leukaemia, all cancers, prostate$|
|2||Nasopharynx, soft tissues, melanoma, cervix uteri, brain, thyroid gland, bone^|
|3||Testis, Hodgkins disease, acute lymphatic leukaemia|
* Table excerpted from: Corazziari I, Quinn M, Capocaccia R. Standard cancer patient population for age standardising survival ratios. Eur J Cancer. 2004 Oct;40(15):2307-16. Table 2, Cancer sites for which each of the three proposed cancer standard populations apply; p.2310. [PubMed]
$ There is an additional system-supplied variable, "Age Standard for Survival Prostate Cancer (15-54,55-64,65-74,75-84,85+)", for use with prostate cancer.
^ For bone cancers, Corazziari et al. (2004) recommend using ages 20+ for survival.
Age Variables and Population Weights
For each of the three standard populations, SEER*Stat provides weights by 5-year age groups using the age variable, "Age recode with <1 year olds", and by five larger age groups, defined by Corazziari et al. (2004), in the system-supplied variable, “Age Standard for Survival (15-44, 45-54, 55-64, 65-74, 75+)”. Weights for ages under 15 are zero.
The standards by 5-year age groups available in SEER*Stat are:
ICSS Population Weights used in SEER*Stat by 5-year Age Group
|Age recode with <1 year olds||Population Weights|
|ICSS 1||ICSS 2||ICSS 3|
When using age standardization in SEER*Stat survival sessions, the system-provided age variable, "Age Standard for Survival (15-44, 45-54, 55-64, 65-74, 75+)", is based on the age recode variable and is the default selection. The population weights for the five broad age groups are the sum of the weights for the corresponding age groups in the SEER*Stat age recode variable. The SEER*Stat 5-year standards vary slightly from the 5-year age standards provided in the Corazziari paper. We included one more digit in the standards, so when summed, the 5-year standards would match the standards for the larger age groups 15-44, 45-54, 55-64, 65-74, 75+.
The standards by the larger age groups are:
ICSS Weights used in SEER*Stat using the Five Default Age Groups
|Age Standard for Survival||Population Weights|
|ICSS 1||ICSS 2||ICSS 3|
Age Variable for Prostate Cancer
There is an additional system-supplied variable, "Age Standard for Survival Prostate Cancer (15-54,55-64,65-74,75-84,85+)", for use with prostate cancer.
ICSS 1 Weights used in SEER*Stat for the Variable "Age Standard for Survival Prostate Cancer (15-54,55-64,65-74,75-84,85+) "
|Age Standard for Survival||ICSS 1 Population Weights|