A total of 33,232 incident CRC cases were reported during the study period, 56% from private healthcare sector laboratories, and 44% from public healthcare sector laboratories. Of CRC incident cases, 54% were males. Throughout the study period, the annual median incidence was 2,292 cases per year (interquartile range (IQR): 2132 - 3081). The mean age at diagnosis was 61 years (±14.9 standard deviation (SD) years). The White population group had the highest percentage of CRC cases (49%) compared to other population groups. (Table 1).
There were 26,836 CRC deaths with an annual median of 2,138 (IQR: 1982 -2321) between 2002 and 2014. Females accounted for 53% of all CRC deaths. The mean age at death was 65 years (±14.9 SD years), and 63% of the deaths were among adults over 60 years of age. The White population group reported the highest proportion of deaths for CRC at 41%, while the Asian population group reported the lowest deaths at 4%. The mortality incidence ratio by age group was highest among Black population group and lowest among White population group (data not shown). Almost 4% of individuals who died from CRC had no education, while 24% reached a high school level. A third of CRC deaths (33%) were reported amongst non-smokers, although 56% of this data was missing from the death registry. The smoking frequencies observed may reflect smoking cessation post-cancer diagnosis.
Table 1
Characteristics of Colorectal cancer cases and deaths (2002-2014)
|
Colorectal cancer cases, (N=33,232)
N(%)
|
Colorectal cancer death, (N=26,836)
N(%)
|
Age
|
|
|
Mean (SD)
|
61.70(±14.38)
|
65.19 (±14.91)
|
Age group (years)
|
|
|
<15
|
24 (0.1%)
|
20 (0.1%)
|
15-30
|
894 (2.7%)
|
551 (2.1%)
|
31-45
|
3,578 (10.8%)
|
2,272 (8.5%)
|
46-60
|
9,817 (29.5%)
|
6,447 (24.0%)
|
>60
|
17,760 (53.4%)
|
16,915 (63.0%)
|
Missing
|
1,159 (3.5%)
|
631 (2.4%)
|
Sex
|
|
|
Female
|
15,208 (45.8%)
|
14,109 (52.6%)
|
Male
|
17,995 (54.1%)
|
12,702 (47.3%)
|
Missing
|
29(0.1%)
|
25 (0.1%)
|
Population group
|
|
|
Black
|
8,942 (26.9%)
|
7,163 (26.7%)
|
Coloured
|
4,613 (13.9%)
|
2,645 (9.9%)
|
Asian
|
1,878 (5.7%)
|
1,169 (4.4%)
|
White
|
1,6207 (48.8%)
|
10,919 (40.7%)
|
Missing
|
1,592 (4.8%)
|
4,940 (18.4%)
|
Laboratory type
|
|
|
Private
|
18,666 (56.2%)
|
-
|
Public
|
14,566 (43.8%)
|
-
|
Smoking Status
|
|
|
No
|
-
|
8,960 (33.4%)
|
Yes
|
-
|
2,726 (10.2%)
|
Missing
|
-
|
15,150 (56.5%)
|
Marital status
|
|
|
Divorced
|
-
|
4,412 (16.4%)
|
Married
|
-
|
10,630 (39.6%)
|
Never_Married
|
-
|
4,887 (18.2%)
|
Widowed
|
-
|
2,648 (9.9%)
|
Missing
|
-
|
4,259 (15.9%)
|
Education level
|
|
|
No_Education
|
-
|
1,074 (4.0%)
|
Primary_School
|
-
|
1,974 (7.4%)
|
High_School
|
-
|
6,391 (23.8%)
|
Tertiary
|
-
|
1,551 (5.8%)
|
Missing
|
-
|
15,846 (59.0%)
|
Age-specific incidence and mortality rates
Figures 1 and 2 illustrate age-specific incidence and mortality rates for males and females in SA between 2002 and 2014. Rates in males and females increased proportionally until the age of 50 years, after which the rate for males was higher than the rate for females for both incidence and mortality. Rates peaked in the age group of 75 years and older.
Age-standardised incidence rates trends
On average, for males and females combined, there was 2.5% annual average increase in ASIR from 2002 to 2014 (annual average percentage change (AAPC)=2.5, 95% CI: 0.6- 4.5, p-value < 0.001) (Table 2). ASIR ranged from 11.6 to 13.5 and 8.5 to 10.6 / 100,000 population for the study period among males and females, respectively. Overall the ASIR were higher among males compared with females (Figures 3 & 4).
Among males, the highest ASIR was observed among the White population group at 28.12 per 100,000 population in 2014. This rate was 1.3, 1.4, and 8.6 times higher than Coloured (19.83/100,000), Asian (21.31/100,000), and Black (3.26/100,000) population groups, respectively (Figure 4). While the CRC ASIR remained stable among males of the Coloured and Asian population groups, the ASIR among males of the Black population group increased consistently at 3.4% from 2002 to 2014 (AAPC=3.4, 95% CI: 1.5- 5.3, p-value < 0.001) (Table 2). Among males of the White population group, a significant decrease of 8.8% was observed from 2002 to 2007 (AAPC= -8.8, 95% CI: -14.0- -3.2, p-value < 0.001) followed by a 10.4% increase from 2007 to 2014 (AAPC= 10.4, 95%CI: 6.6- 14.4, p-value < 0.001) (Table 2).
As shown in figure 5, the highest ASIR among females were observed in the year 2014 at 18.5 per 100,000 population for the White population group. The ASIR in 2014 were similar for Asian and Coloured population groups at (10.6/100,000) and (10.6/100,000) respectively. In the same year, Black females reported the lowest ASIR at 2.3 per 100,000 population. The ASIR among females of the Coloured and Asian population group remained stable, while the ASIR among females of the Black population group increased consistently at 4.3% from 2002 to 2014 (AAPC=4.3, 95% CI: 1.9- 6.7, p-value < 0.001). Among females of the White population group the ASIR trend remained stable until 2009, when ASIR increased by 14.9% from 2009 to 2014 (AAPC=14.9, 95% CI: 6.4- 24.2, p-value <0.01) (Table 2).
Table 2
Annual Average Percentage Change (AAPC) in CRC incidence and mortality rates by sex and population groups, 2002-2014.
Population group
|
Sex
|
Age-standardised Incidence
Period AAPC (95%CI)
|
Age-standardised Mortality
Period AAPC (95%CI)
|
Asian
|
Males
|
2002-2014
|
0.6 (-2.0,3.2)
|
2002-2014
|
2.4(-0.4, 5.4)
|
Females
|
2002-2014
|
3.7 (-0.2, 7.7)
|
2002-2014
|
-0.3(-2.8, 2.3)
|
Coloured
|
Males
|
2002-2014
|
1.2 (-0.8,3.3)
|
2002-2014
|
3.0*(0.4,5.7)
|
Females
|
2002-2014
|
2.5 (-0.0,5.2)
|
2002-2014
|
1.3(-0.5, 3.1)
|
White
|
Males
|
2002-2007
|
-8.8*(-14.0,-3.2)
|
2002-2014
|
0.5(-0.6,1.6)
|
Males
|
2007-2014
|
10.4*(6.6,14.4)
|
-
|
-
|
Females
|
2002-2009
|
-3.7 (-8.0, 0.9)
|
2002-2014
|
-0.2(-1.3,1.0)
|
Females
|
2009-2014
|
14.9*(6.4,24.2)
|
-
|
-
|
Black
|
Males
|
2002-2014
|
3.4*(1.5,5.3)
|
2002-2014
|
4.2*(2.0,6.5)
|
Female
|
2002-2014
|
4.3*(1.9,6.7)
|
2002-2014
|
3.4*(2.0,4.8)
|
All
|
All
|
2002-2014
|
2.5*(0.6,4.5)
|
2002-2014
|
1.3*(0.1,2.6)
|
*The average annual percentage change (AAPC) is statistically significant: p-value <0.05
|
Age-standardised mortality rates trends
On average, for males and females combined, the ASMR increased by 1.3% from 2002 to 2014 (AAPC=1.3, 95% CI: 0.1- 2.6, p-value <0.01) (Table 2). The overall ASMR ranged from 7.1 to 8.9 and 5.5 to 5.9 /100,000 population for the study period among males and females, respectively. Similar to ASIR, the overall ASMR was higher in males than females (Figures 5 & 6).
The highest ASMR in males was observed in the White population group in 2004 at 15.1 per 100,000 population, and this rate was 1.2, 1.7 and 6.0 times higher than the Asian (12.2/100,000), Coloured (8.6/100,000), and Black (2.5/100,000) population groups in 2004, respectively (Figure 5). For males, over the study period, the ASMR remained stable among the White and Asian population groups and increased consistently among the Coloured and Black population groups by 3.0% (AAPC=3.0, 95% CI: 0.4- 5.7, p-value <0.01) and 4.2% (AAPC=4.2, 95% CI: 2.0- 6.5, p-value <0.01) from 2002 to 2014, respectively (Table 2).
Among females the highest ASMR was reported among the White population group at 10.3 per 100,000 population in 2004, this rate was 1.4, 1.5 and 6.3 times higher than the Asian (7.3/100,000), Coloured (6.8/100,000) and the Black (1.6/100,000) population groups, respectively (Figure 6). Among females, a significant change in ASMR was only observed among the Black population group, where the ASMR increased by 3.4% from 2002 to 2014 (AAPC=3.4, 95% CI: 2.0- 4.8, p-value <0.01) (table 2). The ASMR of females among other population groups remained stable (Table 2).