Clinicopathological characteristics of early onset colorectal cancer

Background: The rising incidence of early onset colorectal cancer (EOCRC) might reflect a novel tumour entity. Aims: To evaluate clinicopathological characteristics of sporadic EOCRC (in patients < 50 years old) and investigate changes over time. Methods: All patients with sporadic EOCRC between 1989 and 2016 were included and divided by age: 20-29 years (group I), 30-39 years (group II) and 40-49 years (group III). Results: We included 6400 patients. The presence of signet-ring cells and more poorly differentiated tumours were more common in the younger age groups: 5.4% and 3.7% for signet-ring cells in group I and II vs 1.4% in group III (P < 0.01), and 28.5% and 20.3% for poorly differentiated in group I and II vs 16.6% in group III, (P < 0.01 group I; P = 0.07 group II). Positive lymph nodes were more frequently observed in the younger age groups: 16.2% in group I vs 9.3% in group II (P = 0.01) and 7.9% (P < 0.01) in group III. Over time, a greater proportion of CRCs were diagnosed in women in group I (34.5% < 2004 vs 54.9%>2005, P = 0.09), and a higher percentage of rectal cancer was found in age group III (34.3% < 2004 vs 40.7% > 2005, P < 0.01). Mean overall survival was 6.3 years and improved over time. Conclusions: EOCRC is not only characterised by age of onset but also by the more frequent presence of signet-ring cells, more poorly differentiated tumours, and higher risk of lymph node metastases. In the most recent years, a higher proportion of rectal cancer was found from the age of 30 years, and a higher proportion of CRCs were diagnosed in females below the age of 30 years.