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Colorectal Cancer: Causes, symptoms and prevention

Post by on Sunday, March 13, 2022

First slide

STOP IT BEFORE IT STARTS

 

Epidemiology

Colorectal cancer is a preventable disease & is the world’s third most common cancer. Every year in March, awareness of colorectal cancer regarding prevention & early detection (screening) is raised all over the world to decrease the incidence & detect the disease in early (curable) stage. As per Globocon 2020 report, it accounts around 10% of all cancers & 9.4% cancer related mortalities throughout the world. In India, colorectal cancer represents 2% of all cancers & around 26880 cases has been registered in different cancer registries all over the country (NCRP 2021 Report). However, CRC is the 4th most common cancer in our Kashmir valley and represents around 7% of all cancers (Khan NA et al ;).

 

Considering the high incidence of CRC all over the world as well as in our part of country, there is dire need to undertake broader action to promote knowledge regarding prevention & early detection of this disease. This may definitely help to decrease incidence as well as increase chances of detecting the disease in early (curable) stage. It is important to note here that if the disease is detected in early stage, there is no need of radical approach for treatment & hence, less therapy induced morbidities & mortalities. So besides curing the disease, the quality of life of such patients will be maintained.

 

Risk factors & their Prevention

Colorectal cancer is associated with several recognized modifiable & non-modifiable risk factors. High intake of red and processed meat, sedentary life Style, obesity, tobacco smoking & alcohol consumption are some of the common modifiable risk factors for colorectal cancer. High consumption of red and processed meat is significantly associated with an increased risk of colorectal cancer. There is around 20% increased risk of developing CRC in people with high consumption of red & processed meat as compared to people with relatively low intake of red & processed meat.

 

Frying, grilling, broiling, or cooking meat over coal at high temperatures can lead to the formation of mutagenic and carcinogenic heterocyclic amines through the interaction of muscle creatine with amino acids and to the formation of N-nitroso compounds. Such substances can induce genetic alterations and form DNA adducts characteristic of colorectal tumors. However, Fish and poultry (alternative sources of protein) have been shown to reduce the risk of colorectal cancer. So, a preventive diet for CRC involves limitation of red or processed meats and consumption of white meat and fish. Besides poor diet, sedentary life style & obesity are two other major risk factors for colorectal cancer.

 

During the past few decades, it has been observed that physical activity levels for both adults and children have steadily declined (especially in developed countries). Those declines in physical activities are suggested to be a result of more time spent watching television, playing computer games and of a decrease in opportunities for physical activity in schools and communities & thus, results in obesity. Various studies have shown that high body mass index & low levels of physical activities are significantly associated with development of colorectal cancer (White MC et al ;).

 

In addition to above, alcohol consumption and cigarette smoking are regarded as two other major risk factors for gastrointestinal cancer, including colorectal cancer (Verma M et al ;). Alcohol as well as cigarette smoking is classified as Group 1 carcinogens with sufficient evidence for colorectal cancer. Cancer Research Fund/American Institute of Cancer Research suggests that there is increased risk of colorectal cancer caused by excessive alcohol consumption (more than 30 g per day of ethanol).

 

Age, inflammatory bowel disease, history of CRC in first-degree relatives, and hereditary factors are some of the non-modifiable risk factors for CRC. The risk of colorectal cancer increases as people get older. Colorectal cancer can occur in young adults and teenagers, but the majority of colorectal cancers occur in people older than 50 years of age. However, it is important to note that while colorectal cancer is still diagnosed most commonly in older adults, the incidence rate for colorectal cancer declined by about 3.6% per year in adults ( aged 55 and older) & increased by 2% per year in adults younger than 55. The reason for this rise in younger adults is not well known and is an active area of research. In addition, most of CRC cases are sporadic and only a small percentage (<5%) are hereditary.

 

So, it is important to consult a genetic counsellor if there is family history of colorectal cancer for testing to find out the specific mutation and such high risk cases can be considered for screening at earlier age to reduce incidence & mortality by detecting the disease in early (curable) stage. In summary, most of the risk factors related to development of colorectal cancer are modifiable & are highly prevalent in our society. Hence, there is dire need to undertake strong and broader action to promote the health knowledge regarding colorectal cancer to decrease incidence and detect the disease in early (curable) disease.

 

Symptoms

Many patients don’t have symptoms in early stages of the disease.  When symptoms appear, they may vary depending on location & size of tumour. A persistent change in bowl habits including diarrhoea or constipation or change in the consistency of stools, rectal bleeding or blood in stools, weakness or fatigue and unexplained weight loss are some of the typical symptoms of colorectal cancer. Don’t neglect and consult a doctor immediately if somebody is persistently experiencing one or more of the above symptoms.

 

Lastly, I will conclude with the message to eat healthy diet (consume more plant-based foods and less red & processed meats), quit smoking, reduce or avoid alcohol consumption, avoid sedentary lifestyles (regular exercise) and manage your weight. These measures may definitely help in reduction of incidence and colorectal cancer related mortalities.

 

 

(Dr Mushtaq Ahmad Sofi is Assistant Professor, Radiation Oncology (SKIMS)

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