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Tumour Site/ Type Demographics

​Incidence

2823 Neuro-Oncology cases were diagnosed between 1 January 1987 and 31 December 1996. This sample includes all BC residents diagnosed with either benign disease or malignant tumors during this ten-year period.

Incidence by gender and diagnosis year for the last 5 years of this ten-year interval is presented in the table:

Diagnosis Year199219931994199519961992-19961987-1996
Females1091401441441426791227
Males1691691601872048891596
Total27830930433134615682823


Linear regression analysis of the incidence and mortality trends indicates that incidence tends to increase on average by almost 13 cases each year (p-value < 0.001) and mortality increases on average by 4 cases a year (p-value = 0.02). To determine if those trends are only due to the growth and aging of BC population age-standardized incidence and mortality rates were calculated.

AGE-STANDARDIZED INCIDENCE AND MORTALITY 

These rates are standardized to the age distribution of the 1991 Canadian Population. The plot indicates only a very slight increasing trend of approximately 1 case per 400,000, per year in the incidence (p-value = 0.061) and no increase in mortality.

These rates are standardized to the age distribution of the 1991 Canadian Population. The plot indicates only a very slight increasing trend of approximately 1 case per 400,000 per year in the incidence (p-value = 0.061) and no increase in mortality.

Break down of the incidence by diagnosis type:

SUBGROUPFrequencyPercent of Total
Astrocytoma163657.95
Oligodendroglioma1535.42
Ependymoma672.37
Meningioma2589.14
Pituitary Adenoma1926.80
Others51718.31
Total2823100


AGE

The age of patients diagnosed in BC during these ten years ranges from 0 to 99 years. Three quarters of diagnosed patients were 39 year old and older, median age at diagnosis was 57 years and the mean was 53.1 years. Age distribution is presented on the histogram below:

AGE AT DIAGNOSIS VS. NUMBER OF CASES 

REFERRAL

NEURO-ONCOLOGY CASES DIAGNOSED IN 1987-1996 INCIDENCE AND BCCA REFERRALS BY DIAGNOSIS YEAR 

The plot shows that the majority (72.3%) of diagnosed cases was referred to BCCA. It also suggests that the number of non-referred cases tends to increase over the ten years. Linear regression analysis indicates that this number increases on average by 9 cases per year (p < 0.001). Such increase is not only due to increase in incidence; relative to the total number of diagnosed cases the percent of non-referred cases increases by about 2 each year (p = 0.001).

ASTROCYTOMA

As indicated in the table of the incidence by diagnosis type astrocytoma has the most frequent diagnosis (57.95% of incidence). Severity of the disease is reflected by its grade.

Break down of Astrocytoma incidence by Grade:

GRADEFrequencyPercent
Grade 1553.36
Grade 21509.17
Grade 327516.81
Grade 469242.30
Unknown784.77
Blank38623.59
Total1636100


The plot indicates substantial difference in survival for the four grades of astrocytoma. The estimates for Grade 1 diagnosis are rather unreliable, due to the low number of cases in the sample; the estimated median survival for this grade is longer than 10 years. The median survival for Grade 2 is 4.9 years, 95% confidence interval for this estimate is from 4.1 to 6.7 years. The median survival time for Grade 3 is only 1 year with 95% confidence interval is from 0.9 to 1.3 years. The median survival time for Grade 4 is even shorter: 0.6 year with 95% confidence interval of 0.6 to 0.7 year.

Estimated Probability of Surviving up to 1, 3, 5 and 7 Years after Diagnosis:

Estimated Probability
of Surviving
Years After Diagnosis
1 year3 years5 years7 years
Grade 185.5%69.0%61.3%60.7%
Grade 281.9%67.4%49.8%36.7%
Grade 349.5%27.3%21.7%19.2%
Grade 423.4%3.3%1.2%0.9%

SOURCE: Tumour Site/ Type Demographics ( )
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