ABSTRACT
Background and Objectives: Previously published epidemiologic data from Trinidad and Tobago suggested that left-sided colorectal cancer (CRC) was more common, but accepted, standardized definitions for CRC laterality were not used. This study aims to collect data from patients with CRC in Trinidad & Tobago in order to determine anatomic site using standardized definitions. Methods: A retrospective audit of hospital records was carried out for all patients with CRC over a 10-year period from January 1, 2011 to January 30, 2021. Standardized definitions were used to classify CRC laterality: Right-sided CRC was defined as those that arose in the cecum, ascending colon, hepatic flexure and/or transverse colon. Left-sided primaries were defined as those that originated from the splenic flexure, descending colon and/or sigmoid colon. The following data were extracted: laterality, gender, age and ethnicity. Descriptive statistical analyses were generated with SPSS version 21. Results: The records of 326 patients with CRC were examined in this study. There was a predominance of right-sided (43%) over left sided primaries. There was a statistically significant relationship between right sided CRC and female (58.2% vs. 41.8%; P = 0.00168), black ethnicity (60.2% vs. 38.6%; P = 0.0076) and younger age (60.9 vs. 65.9 years; P = 0.00028). Conclusion: There is a predominance of right-sided CRC in this eastern Caribbean nation, significantly associated with younger, female and black population.
Key words: colorectal cancer, anatomic site, standardized definitions
INTRODUCTION
Trinidad & Tobago is an island state in the Eastern Caribbean with a population of 1,394,969 persons. In this nation, colorectal cancer (CRC) is the third commonest cause of cancer related deaths.[1] Previously published epidemiologic data from Trinidad & Tobago suggested that left-sided lesions were more common, accounting for 73% of all CRC primaries in this nation.[2] This was published in the year 2017[2] at a time when there was a global trend for a shift toward right-sided CRC lesions.[3,4]
More detailed analysis of the publication, revealed that the authors did not use the accepted, standardized definitions for CRC laterality. In international literature,[5–7] right-sided lesions are those arising in the caecum, ascending colon, hepatic flexure and transverse colon, left-sided lesions are those arising from the splenic flexure, descending and/or sigmoid colon, while rectal cancers are considered separately. This is a very important definition because location of the primary has a significant prognostic effect on response to treatment and cancer related mortality.[5–7]
We carried out this study to collect data from patients with CRC in Trinidad & Tobago in order to determine anatomic site using standardized definitions.
METHODS
In Trinidad & Tobago, all legal residents are offered free government-funded health care. In this government-funded healthcare system, all patients with colorectal carcinoma who have biopsies taken at colonoscopy and/or specimens extracted at surgery have their specimens examined at the pathology department of the Port of Spain General Hospital. This facility serves the north-western part of the nation, with a catchment population of approximately 675,000 persons. We secured permission from the institutional review board to retrospectively audit hospital records of patients with CRC who had specimens examined over a 10-year period from January 1, 2011 to January 30, 2021.
In this study, we utilized standardized definitions to classify the laterality of CRC primaries. Right-sided primaries were defined as those that arose in the cecum, ascending colon, hepatic flexure and/or transverse colon.[5–7] Left-sided primaries were defined as those that originated from the splenic flexure, descending colon and/or sigmoid colon.[5–7] Rectal lesions were considered separately.
All pathology reports were reviewed and associated data were extracted from, including gender, age and ethnicity. Descriptive statistical analyses were generated with SPSS version 21.0 using the Chi square test of independence to investigate correlations. Independent, continuous variables were compared using the two-tailed Mann-Whitney U test for non-parametric groups, with a significance level of 0.05.
RESULTS
Over the study period, there were 470 patients with CRC who had specimens examined at the General Hospital in Port of Spain. Paper based records for 39 patients could not be located and they were excluded from the final analysis. Since this study sought to determine laterality, 100 patients with rectal cancers were also excluded from the final analysis. The final study population comprised 326 patients with CRC.
Using the standardized definitions, there was a predominance of right sided lesions (43%), compared to left-sided (34%) or rectal lesions (23%). Synchronous carcinomas were detected in 5 (1.2%) of patients with CRC, usually as a part of polyposis syndromes.
On subgroup analysis, right sided lesions were present in 182 persons at a mean age of 60.9 years (SD 13.5, range 27–93). In this group, there was a statistically significant preponderance of females, association with black ethnicity and younger age (Table 1).
| Parameter | Right-sided colorectal cancer | Left-sided colorectal cancer | P value |
| Number of patients, n (%) | 182 (55.8) | 144 (44.2) | 0.00288 |
| Age (yr) | 60.9 ± 13.5 | 65.9 ± 13.64 | 0.00028 |
| Male, n (%) | 76 (52.8) | 68 (47.2) | 0.34722 |
| Female, n (%) | 106 (58.2) | 76 (41.8) | 0.00168 |
Left sided lesions were present in 144 patients at a mean age of 65.9 ± 13.64 (range 26–90). There was a slight male preponderance which did not attain statistical significance.
Patient ethnicity was recorded in 153 cases (Table 2). Overall, 77 (50.3%) persons treated for CRC were of Afro-Caribbean ethnicity, 49 (32%) were of Indio-Caribbean ethnicity and 26 (17%) were mixed ethnicity. There was a significant association between Afro-Caribbean ethnicity and right sided CRC and an association between Indio-Caribbean ethnicity and left-sided CRC as outlined in Table 2.
| Ethnicity | Right-sided colorectal cancer | Left-sided colorectal cancer | P value |
| Afro-Caribbean | 50/83 (60.2) | 27/70 (38.6) | 0.00758 |
| Indio-Caribbean | 17/83 (20.5) | 32/70 (45.7) | 0.00086 |
| Mixed ethnicity | 16/83 (19.3) | 11/70 (15.7) | 0.56192 |
DISCUSSION
This study provides epidemiologic data from patients with CRC in Trinidad & Tobago that will be useful to guide screening programmes. It corrects the previous record suggesting that left-sided disease was more common in this nation. This data is in keeping with international data[3–5] documenting an increasing prevalence of right-sided CRC.
Caribbean countries have reported similar patterns of right-sided CRC predominance.[6,8,9–11] The prevalence of right sided lesions in Barbados is 44.3% as reported by Griffith et al.[6] In Jamaica, McFarlane et al.[8] reported right sided lesions in 28.5% and in Martinique, Joachim et al.[6] reported right sided lesions in 26.3% of patients. We found right-sided lesions in 42.7% of Trinidadian patients, which was unexpected as they approximated figures from Barbados, that ranks globally in the top ten nations for CRC incidence.[1]
The only Caribbean study that suggested a left-sided prevalence was the previously cited study from Trinidad & Tobago[2] that examined 118 resected specimens. This study was flawed for two reasons: first, the authors assigned rectal primaries as left-sided lesions, contrary to most definitions. They also defined right-sided lesions as those “found in the ascending colon, including the caecum, and up to the proximal half of the transverse colon”. It has already been pointed out that this is not the accepted, standardized definition. The definition is important because left and right sided CRC have fundamentally different clinical behaviours.[7] Right sided lesions have a greater association with microsatellite instability,[12] and poorer survival statistics.[13] For this reason, there is consensus on the definition of geographic origin of the primary.[4–7] The standardized definition of a right-sided CRC is one that originates in the caecum, ascending colon, hepatic flexure and/or transverse colon, while a left-sided lesion is one that arises from the splenic flexure, descending and/or sigmoid colon.[4–7] Rectal cancers are not included in the definition of laterality.
The high proportion of Afro-Caribbean patients (50.3%) was notable, since the population in Trinidad & Tobago is equally divided amongst Afro (40%) and Indio-Caribbean (40%) ethnicities.[14] But it was not unexpected since international data has shown that, compared to other ethnicities, blacks tend to have a higher incidence of CRC,[15,16] increased association with genetic mutations,[12,17] and a more aggressive disease course.[12,17,18]
We also demonstrated that women were statistically more likely to develop right-sided CRCs than males. This pattern is similar to that reported in other countries[19–22] and it has clinically significance since right-sided CRC have more aggressive behaviour and poorer survival statistics.[12,19–23]
Our study was limited by the unavailability of immunohistochemical and molecular predictive biomarkers for CRC. It is estimated that genetic factors such as mis-match repair gene mutations and MUTYH genes contribute to CRC incidence in up to one third of patients.[12] These markers were not universally available for evaluation in the present study.
CONCLUSION
This study collected epidemiologic data from patients with CRC in Trinidad & Tobago. There is a predominance of right-sided CRC in this country, with a significant association with younger, female and black population.
DECLARATIONS
Acknowledgments
No acknowledgements are required.
Author contributions
Shamir O. Cawich, Alyssa Muddeen, and Mikhaiel Barrow conceptualized the study, collected data and wrote the paper. Kavi Capildeo, Nazreen Bhim, and Shaheeba Barrow performed statistical analysis, contributed to the scientific discussion and checked the manuscript for accuracy. All authors reviewed scientific content for the final manuscript.
Source of funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflicts of interest
There is no conflict of interest among the authors.
Data sharing statement
No additional data is available.
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