Colorectal cancer is a major health problem, incidence and mortality rates vary markedly around the world. Colorectal cancer is the third most commonly diagnosed cancer type in the world, with almost two million new cases. It is predominantly a disease of older people, with the highest incidence rates amongst adults aged 70 and over [1].  Studies have shown that incidence of colorectal cancer is increasing in population currently not been targeted by screening programmers, especially adolescents and young adults [2-6]. Colorectal carcinoma is the second most commonly diagnosed cancer and is a leading cause of cancer death in Europe [7-8]. Globally, colorectal cancer is the second most common cause of cancer death causing almost one million deaths, rates are substantially higher in males than in females. Most colorectal cancers (CRC) arise from adenomatous colon polyps that progress from small (<8 mm) to large (≥8 mm) polyps, then to dysplasia and carcinoma. Colorectal cancer can be categorized by location of their primary tumour within the colon and rectum [9]. Within the colon, about 50% of cancers arise in the left side and 25% in the right; in 4-5% of cases there are synchronous lesions. Embryologically Right-sided colon  are derived from midgut, which encompasses the proximal two-thirds of the transverse colon, ascending colon and caecum and the Left-sided colon derived from the hindgut, which includes the distal third of the transverse colon, splenic flexure, descending colon, sigmoid colon and rectum, Sometimes, the rectum is described separately, despite originating from the hindgut, and in several clinical series, the left sided colon includes only tumours within and distal to the splenic flexure (Figure 1) .

Figure 1: Tumour locations.

Colon cancer on right side tend to be diagnosed much later than left-sided colon cancers, this may be due to the symptoms produced on the right side when they are relatively advanced. The clinical outcome of colorectal cancer has greatly improved because of improved diagnosis and referral for surgery, in addition to expansion in available systemic therapies and ablative techniques [10].

Aim

To investigate the incidence trend of colorectal cancer and analyzed its characteristics by gender, age, site and other aspects.

Dunstable University Hospital UK from January 2015 through December 2019 were retrospectively identified from the referral database created by the colorectal specialist nurses in the colorectal service. Data were retrieved by detailed review of the hospital case notes, ICE / Evolve (Computer database for investigations and correspondence) including endoscopy; radiographic imaging; operative course and cancer follow up. The following parameters were recorded: age, gender, and source of referral, presentation, stage of the disease, MDT discussion, intervention, and outcome. Tumour locations were classified as the right colon (i.e. caecum, ascending colon, hepatic flexure, transverse colon, and the left colon (i.e. spleenic flexure, descending colon, sigmoid, Recto sigmoid, and rectum.

Inclusion

All patients diagnosed with colorectal cancer

Exclusion

Tumours in the Appendix, Anal canal, small bowel, metastatic tumours of unknown primary

Statistical Analysis

Data were analyzed using the Statistical Package for Social Sciences (SPSS, version 26). Mean values were compared using the Student t-test (Table 1).

Table 1: Student t test.

Univariate analysis of categorical variables was performed by the chi-square test (Table 2).

Table 2: chi-square test.

Pearson’s chi squared test was used for comparing two proportions (Table 3).

Table 3: Chi-Square tests for intervention.

An OR with corresponding 95% confidence interval >1 implied a positive association where as an OR with corresponding 95% confidence interval <1 implied a negative association. Two-sided p values <0.05 were considered significant (Table 4).

Table 4: Risk Estimate.

Table 5: Characteristics and incidence.

In the study period 976 patients were diagnosed with bowel cancer percentages of studied participant were Male 52.60% and Female 47.40%. The mean age of 74.14 years (range, 25 to 101). 6.76% patients were excluded from the study on the account of Tumours in the Appendix, Anal canal, Small bowel and metastatic tumour of unknown primary (Figure 2).

Fig 2: Cohort.

The annual incidence rate of colorectal cancer in Luton and Dunstable remains almost steady. Increased significantly, from 16.6% in 2016 to 22.6% in 2017.  (Table 6 Figure 3).

Table 6: Annual incidence rate of colorectal cancer in Luton and Dunstable.

Figure 3: Cases per year/side of cancer.

The location of colon cancer is also changing, the incidence rate of Right side colon cancer in women was much higher than that in men, and on Left side colon cancer including rectum was  much higher in men than  that in women this was especially exhibited in cases of rectal cancer, for which the male to female ratio was increased to 1.54:1 whereas the male to female ratio of left colon cancer 1.26:1 Although the incidence rate of Right colon cancer was slightly higher women than men 1.20:1 (Figure 4).

Figure 4: Gender / Site.

The rectal cancer incidence increased from 20.75% in 2015 to 21.88% in 2018. The most significant increase was noted 22.64% in 2017. In the Age group 20-49 years incidence of colorectal cancer was 5.38% in the 50-79 years group, the incidence remained the highest 65.05% while Age group 80-99 year’s incidence 28.90% and over age group 100 years 0.65%. (Table 7 Figure5).

Table 7: Cancer colon.

Figure 5: Age / Cases.

Table 8: Cancer / Gender.

Table 8(a): Cancer / Gender.

The proportion of distal colon cancer was increasing annually, rising to 22.88% in 2018. The proportion of colorectal cancer in women increase from 7.58% in 2015 to 10.43% in 2019. All studied cases were classified into four groups according to the age at diagnosis (Table 7). The incidence rates were increasing in all groups over time, especially in the 50-79 years group.  69.89% patients underwent surgical intervention. 24.50% patients deemed unsuitable for resection surgery were treated with best supportive care palliatively. In the Right colon subset of patients there was a total of 37.58% patients 189 Female and 153 Male, in 33.29% patients with Left Colon cancer there were 169 Male and 134 Female.  Of 29.12% Rectal cancer patients there were 161 Male and 104 Female. 32.08 % patients died during the study period. Incidence of colorectal cancer was greater for cancers of the left side of colon than right colon (62.41% vs 37.58%).

Colorectal cancer is one of the most common and lethal cancer worldwide, and it exhibits differences in incidence, pathogenesis, molecular pathways, and outcome depending on the location of the tumour. Bowel cancer can affect anyone of any age, in the United Kingdom, age-standardized incidence have remained constant, but incidence rates in aged 20-39 have increased in the last 25 years [11]. Age-standardized incidence rates of bowel cancer for females in the UK remained stable between 1993-1995 and 2015-2017, and for males, bowel cancer age-standardized incidence rates in the UK decreased by 3% between 1993-1995 and 2015-2017. In the UK between 2005-2007 and 2015-2017, bowel cancer age-standardized incidence rates for males and females combined decreased by 4%. In males age-standardized incidence rates decreased by 6%., and in females rates decreased by 2%. In  our study the Age group 20-49 years incidence of colorectal cancer was 5.38% this is in contrast to study of Vuik FE, Bento MJ, et al. Increasing incidence of colorectal cancer in young adults in Europe over the last 25 years [11]. More than nine out of ten new cases (94%) are diagnosed in people over the age of 50, and nearly six out of ten cases (59%) are diagnosed in people aged 70 or over, 30% of patients with Colorectal cancer present with a metastatic disease [12-13] In current study Bowel cancer incidence is strongly related to age, with the highest incidence rates being in older people. Age-specific incidence rates rise steeply from around age 50-79. The highest rates are in the 70 to 79 age group for females and males, while  Age group 80-99 years incidence 28.90% and over age group 100 years 0.65%. In the UK bowel cancer is the 3rd most common cancer in both sexes. In males (13% of all new male cancer cases) and in females, (10% of all new female cancer cases). A comparable or greater proportion of patients with Right colon cancer are female, and the median age of patients with Right colon cancer at diagnosis is higher compared to patients with Left colon cancer [14-16]. 56 % of bowel cancer cases in the UK are in males, and 56% are in females. This is in contrast to our study, in our study there were 52.74% Male and 47.25% Female. Published Studies have shown that incidence of right sided colon cancers are becoming more frequent with a drop in the cancer of left sided colon [17-18]. The location of colon cancer is also changing. The colonic distribution of cancer has had a relative rightward shift over the past 3 decades [19]. In our study we found 70.87% of cancers were in the colon and 29.12% were in the rectum. Waldron and Donovan revealed that 23% of colorectal tumours were right sided [20]. Crerand S, Freely TM, Waldron RP, et al study in Dublin revealed that approximately 28% of colorectal tumours were right sided [21] and Hayne D, Brown RS, McCormack M, et al study on the current trends of colorectal cancer in England and Wales concluded that approximately 29% of colorectal cancers were right sided [22]. This is in contrast to our study; we found Right colon cancer was 37.58 %. The findings from our study suggest Left colon cancer was 33.29% and 29.12% of cancer were in the Rectum this is similar to other published studies [23-24]. In our study 15.10% had complications after surgery (Figure 6) and age is not a predictor of post-operative complications.

Figure 6: Complications.

Five-year survival for bowel cancer shows an unusual pattern with age: survival overall decreases with increasing age [25]. In 1990 report on prognostic effect of primary tumour localization on clinical outcome was first reported [26]. In a FIRE-1 trial, Right colon cancer patients had a considerably shorter progression-free survival and overall survival compared with Left colon cancer [27]. This is similar to our study, Overall 5-year survival in our study for right-sided tumours was 24.94%. In comparison, survival rates were 42.96% for patients with left-sided tumours. In current study 32.08% patients died during the study period. (Table 9 Figure 7).

Figure 7: Mortality.

Table 9: Mortality.

The choice of treatment is based on several factors, including conditions of the patient stage at presentation, and the location of tumour. Surgery remains the core in curative treatment for colorectal cancer. One of the strengths of our study is that the sample size is not small, Patients admitted as an emergency and scheduled for elective surgery for confirmed colorectal cancer were included and long follow-up period. The limitation of this study is single center, retrospective. Many studies have reported that oncologic outcomes of colon cancer are different according to the tumour location. Most studies have reported poorer oncologic outcomes in patients with Right colon cancer compared with patients with Left colon cancer [28-32]. However, our study have reported that the prognosis of Right colon cancer is better than that of Left colon cancer this is similar to other published studies [33-34]. Age on its own would not be taken as for less aggressive therapy; Careful assessment of the patient taking into consideration comorbidities, functional status and patient wishes are essential in decision making and choosing appropriate management plan. Management of comorbidities preceding surgery may impact postoperative outcome.

We found that tumour location is associated with prognosis in colorectal cancer patients, Left sided colon cancers have a worse prognosis than Right sided colon cancers. Right sided colon cancers, should be treated distinctively from Left sided colon cancers, and the establishment of comprehensible management for location of colon cancer is needed.

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