Epidemiology

Colorectal cancer is the third most common cancer in the developed world.​ The lifetime risk of developing colorectal cancer is 4% in both men and women (2018-2021 data; 2020 excluded due to the COVID-19 pandemic).[4] Based on 2017-2021 data, the incidence of colorectal cancer is 36.5 per 100,000 men and women in the US.[4] In 2025, an estimated 107,320 cases of colon cancer and 46,950 cases of rectal cancer will be diagnosed in the US, and an estimated total of 52,900 people will die from these cancers.​​[5]​​​ In the US, the colorectal cancer mortality rate has dropped by 56%, from 29.2 per 100,000 people in 1970 to 12.8 per 100,000 people in 2021, mostly due to earlier detection through screening and improvements in treatment; from 2012 to 2019, the death rate declined steadily by about 1.8% per year. Similar to incidence, however, this progress contrasts with rising mortality in adults younger 55 years since the mid-2000s.[6] Globally, the age-standardised incidence rate is 26.7 per 100,000 people, and the age-standardised mortality rate is 13.7 per 100,000 people.[7]

Age is a major risk factor for sporadic colorectal cancer. Between 2017 and 2021, the median age at diagnosis for cancer of the colon and rectum was 66 years in the US.[4] Between 1990 and 2019, there was a significant increase in colorectal cancer incidence among adults aged <50 years, especially in developed countries.​[3][7]​​​​ In the US, compared with the incidence of advanced disease in 2010, a 3% annual increase in people aged <50 years and a 0.5% to 2% annual increase in people aged 50-64 years has been noted.[8]​ The reason for this rise in early onset disease is unknown, but may be related to changes in diet and resultant effects on gut microbiome and inflammation, and environmental changes such as use of microplastics.[9][10]

Incidence and mortality rates appear to be lower in Hispanic people and Asians/Pacific Islanders than in white people and black people.[4] Some of these disparities may be due to differences in genetic susceptibility, in addition to socioeconomic and environmental factors.

Worldwide, the highest incidence rates for colorectal cancer are seen in western and central Europe, high-income regions of North America, and Australasia. Incidence rates are lowest in Africa, central and south Asia, and central Latin America.[7]

In the UK and Wales, around 35,779 patients were diagnosed with colorectal cancer between April 2021 and March 2022.[11]​ According to Cancer Research UK, due to an increase in older population, the number of people diagnosed with colorectal cancer will increase by around one tenth by 2040, leading to average increase of about 2500 deaths per year.[12]

In the US, the incidence of colorectal cancer is higher in Alaska Natives (88.5 per 100,000), American Indians (46.0 per 100,000), and blacks (41.7 per 100,000) than in whites (35.7 per 100,000).[8]

One population-based cohort study, including more than 60,000 adults aged 66-75 years who underwent colonoscopy, reported that the probability of interval colorectal cancer (defined as diagnosis 6-59 months after colonoscopy) was 7.1% in black people compared with 5.8% in white people.[13] Adjustment for physician polyp detection rate (an indicator of colonoscopy quality), age, sex, and geographical area did not eliminate this significant difference.

The anatomical distribution of colorectal cancer varies by age and between sexes. Women and older patients (≥60 years) are more likely to have tumours in the proximal colon (caecum, ascending, and transverse colon), compared with men.[14][15]

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