What is bowel cancer?
The statistics provided in this report include patients diagnosed with cancer of the colon and rectum, including the rectosigmoid. Collectively, these cancers are referred to as bowel cancer or colorectal cancer.
How common is bowel cancer?
In 2019, 3815 Victorians were diagnosed with bowel cancer. Of these, there were 2091 males and 1724 females, representing 54.8% and 45.2% of the total Victorian bowel cancer diagnoses, respectively. The median age at diagnosis of bowel cancer is 69 years in males and 72 in females (Figure 1 & 2). Accounting for 10.6% of all cancers diagnosed and 11.1% of all cancer-related deaths in 2019, bowel cancer was the 3rd most commonly diagnosed cancer and the 2nd most common cause of cancer-related deaths in Victoria.
Trends in bowel cancer over time
Figure 3 shows that since 1982 incidence of bowel cancer has decreased by an average of 0.4% per year in males and decreased by an average of 0.5% in females. Over the past 37 years, mortality from bowel cancer has decreased by 2.1% per year in males and decreased by 2.4% per year in females.
Bowel cancer morphology
Figure 4 provides a summary of the different types of cells (morphology) which have caused bowel cancer. Most bowel tumours, 82.1%, present as Adenocarcinoma tumours.
Geographical variance in bowel cancer by local government area
Figure 5 demonstrates variation in age-standardised incidence rates of bowel cancer by local government areas. Darker shading indicates areas with higher rates of bowel cancer.
Bowel cancer in people born overseas
Figure 6 shows the age standardised incidence rates of bowel cancer in Australian-born Victorians compared to other major migrant groups, over the five-year period 2015 to 2019. The highest age standardised incidence rate for bowel cancer was 34 for males born in the Other Europe region and the lowest rate of 18.6 was observed in males born in the Southern and Central Asia region. The highest age standardised incidence rate for bowel cancer was 25.2 for females born in the Australia and New Zealand region and lowest rate of 12.4 was observed in females born in the Southern and Central Asia region.
Bowel cancer distribution by stage at diagnosis
Figure 7 shows distribution of bowel cancer by stage of disease at diagnosis in 2019. In males, Stage 1 accounted for the largest proportion (23.3%) of new diagnoses and Stage 4 for the lowest proportion (16.5%) of new bowel cancer diagnoses. In females, Stage unknown accounted for the largest proportion (25.1%) of new diagnoses and Stage 4 accounted for the lowest proportion (16%) of new bowel cancer diagnoses.
Bowel cancer five-year relative survival
Figure 8 demonstrates that five-year relative survival has increased for bowel cancer between 1989-1993 and 2014-2018 from 51% to 70%.