martes, 29 de enero de 2019

Colorectal Cancer and Crohn’s Disease

Download PDF Copy

By Phoebe Hinton-SheleyReviewed by Liji Thomas, MD

The hallmarks of cancer – the characteristic features of cancer formation - include sustaining cell division even after it is no longer needed, as well as evasion of growth suppressor molecules.

The spread of the cancer (metastasis), as well as the formation of a new blood supply and resisting cell death, are all marks of the beginning of a cancerous growth. In addition to these hallmarks of cancer, there are general health conditions which can increase the chances of developing cancer, including inflammation. Inflammation can come about in many ways, including injury or some types of inflammatory disease.

Crohn’s Disease

Crohn’s disease is a relapsing inflammatory bowel disorder, grouped with ulcerative colitis, and is a hereditary condition which directly affects the bowel. It mainly presents as severe gastrointestinal pain, fever, diarrhoea, clinical signs of bowel obstruction, and the passage of blood and mucus. It has been found to affect all ages and ethnicities. It has been the subject of a fair amount of scientific research into treatments and/or cures.

It is an autoimmune disorder – meaning that the patient’s own immune system attacks the cells and tissues of the bowel. The reasons for this are unknown, and treatment therefore consists of immunosuppressant drugs such as very mild chemotherapy tablets. This can leave Crohn’s disease patients at risk of contracting rare diseases, as they are immunocompromised due to both the condition itself, and the immunosuppressant treatments.

Connections Between Crohn’s Disease and Colorectal Cancer

Because Crohn’s Disease is a chronic inflammatory disorder, these patients are at an increased risk of colorectal cancer. However, this is modified by the age of the patients. A study performed in 2014 showed that younger patients with Crohn’s disease had only a slightly elevated risk of colorectal cancer, compared to adult patients who had a moderate risk of colorectal cancer.

It was also observed in this study that male patients were at a much greater risk of developing colorectal cancer (60% higher), as well as having a greater cumulative incidence after 40 years of having the disease. The reason for this extreme increase in risk is unknown. Also, the incidence of colorectal cancer in both Caucasian and African patients with inflammatory bowel disease was found to be almost identical.

It is thought that cancer is a ‘disease of the elderly’, because cancer tends to affect the older generations disproportionately. There are obviously many exceptions to this rule – however, colorectal cancer incidence increases dramatically with age. For example, in a study performed in 2009, under 50 cases of colorectal cancer per 100,000 people in the 45-49 years age category were observed – compared to over 175 cases per 100,000 people in the 65-69 years age category. This number only continued to increase with age – with the causes being attributed to continued cell replication within the bowel, as well as the possibility of chronic inflammatory disorders of the bowel, such as Crohn’s disease, over a long period of time.

Colorectal cancer is not a condition limited to those over the age of 40; however, it is clear that the risk greatly increases with age - especially if the patient already has an inflammatory condition of the bowel. Therefore, patients with Crohn’s disease should undergo regular testing for colorectal cancer, as well as other conditions linked with the disease (e.g. ulcerative colitis).