Influence of Sex and Age on Site of Onset, Morphology, and Site of Metastasis in Colorectal Cancer: A Population-Based Study on Data from Four Italian Cancer Registries

SIMPLE SUMMARY: Colorectal cancer has the third highest cancer incidence in the world. The purpose of our population-based study was to evaluate how non-modifiable factors (sex and age) influence the biological and clinical characteristics of the disease, especially in patients with metastases at diagnosis. Our results indicate that sex and age influence the site of onset, morphology, and metastatic pattern of colorectal cancer, thereby affecting patient survival. Understanding the biological mechanisms that are regulated by sex and age, such as the hormonal profile, may contribute to the earlier diagnosis and better prognosis of this disease. As colorectal cancer is subject to screening, the influence of sex and age should be taken into account to implement a targeted strategy that considers these two factors in the general population. ABSTRACT: The prognosis of colorectal cancer is affected by factors such as site of origin, tumor morphology, and metastasis at diagnosis, but also age and sex seem to play a role. This study aimed to investigate within the Italian population how sex and age interact in influencing certain aspects of the disease and how they affect patient survival, particularly in the metastatic cohort. Data from four cancer registries were collected, and patients were classified by sex and age (<50, 50–69, and >69 years). Two separate analyses were conducted: one for patients having right or left colon cancer with adenocarcinoma or mucinous morphology, and one for patients having metastases at diagnosis. Women showed significant differences in right colon cases from the youngest to oldest age group (36% vs. 45% vs. 60%). Men <50 years had a significantly higher mucinous carcinoma percentage than their female counterparts (22% vs. 11%), while in the oldest age group women had the highest percentage (15% vs. 11%). The metastatic pattern differed between men and women and by age. The three-year relative survival in the <50 age group was better for women than men, but this survival advantage was reversed in the oldest group. In conclusion, sex and age are factors that influence the biological and clinical characteristics of colorectal cancer, affecting the metastatic pattern as well as patient survival.