Colorectal cancer (C18-20)

bowelColorectal cancer, also referred to as bowel cancer, is the third most common cancer in males and the second most common in females worldwide.1 The most prominent non-modifiable risk factor is age, with over 90% of cases being diagnosed in people over 50 years of age.2 Another established non-modifiable risk is adult-attained height[a].3

A personal or family history of colorectal cancer, polyps and specific inherited genetic conditions and a personal history of inflammatory bowel disease increase bowel cancer risk.2, 4 Processed meat, and to a lesser extent red meat, consumption increases risk of bowel cancer as well as alcohol and tobacco consumption. 3, 5-8 Obesity also increases risk whereas physical activity decreases risk.3 Occupational exposure to asbestos and X- and γ-radiation also increase risk.9, 10

Risk_factors_bowelEarly-stage colorectal cancer typically has no symptoms, therefore screening is currently the only method for early diagnosis.2 The Australian screening program started in 2006 and the target age groups are being expanded to provide access for all people aged 50-74 to biennial screening by 2019-20.11-13

bowel_graphOur analysis showed a small overall increase in bowel cancer incidence (2%). In contrast, there was a statistically significant decline of 47% in mortality. Reduced mortality is probably due to improved treatment technology and better adherence to national management and treatment guidelines.14-17 The greatest future reductions in bowel cancer mortality across the whole population are expected to be gained from screening.18 Attaining sufficient coverage of screening is, however, an ongoing challenge in countries that have tried to implement such programs. 

Colorectal cancer deaths and incident cases in Australia 1987–2007

                                     Deaths+ Incident Cases +
Male Female Persons Male Female Persons
Observed in 2007 (O) 1,197 791 1,988 5,121 3,653 8,774
Expected in 2007 (E) § 2,205 1,580 3,785 4,921 3,680 8,600
Difference (O-E)  -1,008 -789 -1,797 200 -27 174
Change in (O-E)/E (%) -47 -50 -47 4 -1 2

#An average of the observed rates for 2006 to 2008 was applied to the 2007 population of Australians aged 74 and under to calculate the observed number of deaths and incident cases for 2007.
§An average of the observed rates for 1986 to 1988 was applied to the 2007 population of Australians aged 74 and under to calculate the expected number of deaths and incident cases for 2007.
+All figures have been rounded to the nearest whole number.

[a] This refers to how tall a person becomes as an adult, largely determined by genetics and environment factors in early life. When indicated as a risk factor, adult-attained height suggests that taller adults have higher risk.

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