Colorectal cancer

Colorectal cancer had a low incidence several decades ago. However, it has become a predominant cancer and now accounts for approximately 10% of cancer-related mortality in western countries. The ‘rise’ of colorectal cancer in developed countries can be attributed to the increasingly ageing population, unfavourable modern dietary habits and an increase in risk factors, such as smoking, low physical exercise and obesity. New treatments for primary and metastatic colorectal cancer have emerged, providing additional options for patients; these treatments include laparoscopic surgery for primary disease, more-aggressive resection of metastatic disease (such as liver and pulmonary metastases), radiotherapy for rectal cancer, and neoadjuvant and palliative chemotherapies. However, these new treatment options have had limited impact on cure rates and long-term survival. For these reasons, and the recognition that colorectal cancer is long preceded by a polypoid precursor, screening programmes have gained momentum. This Primer provides an overview of the current state of the art of knowledge on the epidemiology and mechanisms of colorectal cancer, as well as on diagnosis and treatment.

Introduction

We live in an era with improved worldwide average living standards and increased access to adequate health care that has considerably improved the diagnosis and treatment of diseases. These measures have had an effect on the average life expectancy in most regions of the world. However, although death rates from communicable diseases have improved globally as a result of these medical improvements, cancer-related mortality has increased by almost 40% over the past 40 years. A further 60% increase is expected in the next 15 years, with 13 million people estimated to die of cancer in 2030. The main causes of cancer-related mortality have also changed, attributable to alterations in disease incidence, the introduction of screening programmes and therapeutic improvements. Colorectal cancer was rather rare in 1950, but has become a predominant cancer in western countries, now accounting for approximately 10% of cancer-related mortality. Reasons explaining this increased incidence include an ageing population and the preponderance of poor dietary habits, smoking, low physical activity and obesity in western countries. The change in incidence is not only apparent in the rates of sporadic disease but also in some familial cancer syndromes. Indeed, given that the rates of Helicobacter pyloriinfection (a causative factor of gastric cancer) have fallen dramatically, colorectal cancer is now the predominant presentation of Lynch syndrome (a hereditary non-polyposis type of colorectal cancer), whereas carriers of this syndrome used to be predominantly affected by gastric cancer.

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Source: krmc