Early-onset colorectal cancer: clinical presentation, tumour characteristics and survival

Introduction

Early-onset colorectal cancer (EOCRC) as defined by patients diagnosed at age 50 years and younger represent a distinctive group which present with different clinicopathological features and tumour biology compared to classical/late-onset CRC (LOCRC). While there has been a decline in the incidence of late-onset CRC due to improved detection and screening, there has been a surge of EOCRC often presenting with advanced disease at diagnosis and with largely unknown pathogenesis. We thus aimed to describe the clinical presentation, tumour characteristics and survival of EOCRC compared to LOCRC.

Methods

We retrospectively analysed all patients diagnosed with colorectal cancer from 2019 to 2022 at a single centre. EOCRC were defined as patients diagnosed with CRC at age 50 years and younger, while LOCRC included patients diagnosed at >50 years. Data collection included patient demographics, clinical information, as well as a detailed biochemical, radiological and histological review. Statistical analyses were performed using SPSS and p<0.05 was considered significant.

Results

307 patients were identified (156 female, median age=73 years), of whom, 34 (11.1%) were diagnosed as EOCRC (18 female, median age=44 years). The commonest presentation was haematochezia (n=12, 35%) followed by change in bowel habit in the EOCRC group (p=0.03), compared to a positive faecal immunochemical test (n=102, 37%) and anaemia in the LOCRC group respectively. Over half of all CRC originated from the left colon (22 EOCRC vs 149 LOCRC), however there were no differences in disease distribution between the groups. Thrombocytosis (platelet count >450x10⁹/L) (24% vs 11%, p=0.038*) and tumour budding (12% vs 3%, p=0.006*) were significantly higher in the EOCRC group. There were no differences in the histological subtype, TNM staging and mutational profiling in each group. 28 (82%) vs 191 (70%) in the EOCRC and LOCRC group respectively remained alive over a median follow-up of 16 months, with no differences in survival between the groups (figure 1).

Conclusion

EOCRC represents an important and challenging subtype of CRC, which presents differently from classical LOCRC. The incidence of EOCRC is 11%, which is in keeping with published reports. Haematochezia was the most common presentation, while thrombocytosis and tumour budding were higher in the EOCRC group, suggesting a more advanced phenotype at diagnosis. However, the overall survival was similar in both groups. Prospective research is warranted to elucidate the respective aetiologies, risk factors and tumorigenesis of EOCRC, which will enable timely identification, prevention and treatment of such patients. *Limited by small patient numbers.