Dr. Shyam P Lohani

Cells in our body normally grow, divide, and then die in order to keep the body healthy and functioning properly. Sometimes this process goes beyond control. Cells keep growing uncontrollably and dividing even when they are supposed to die. Colorectal cancer may develop when the cells lining the colon and rectum multiply uncontrolled.
Colon cancer is a type of cancer that starts in the colon (large intestine) or rectum. The large intestine and rectum are the organs that make up the lower portion of our digestive system. Colon cancer typically affects older adults, although it can happen at a young age. It usually begins as small, noncancerous, or benign clumps of cells called polyps that develop inside the colon. Over a period of time, some of these polyps can become colon cancers.

Incidences
In terms of mortality, colorectal cancer is the second leading cause of cancer deaths worldwide. In 2020, an estimated 915,880 people died from colorectal cancer. This figure includes 576,858 people with colon cancer and 339,022 others with rectal cancer (Cancer.Net, 2022). The incidence and mortality rates of colorectal cancer vary markedly around the world. Globally, it is the third most commonly diagnosed cancer in males and the second in females, according to the World Health Organisation (WHO). A large proportion of cases are accounted for behavioural risk factors such as diet, alcohol intake, and physical inactivity.

The highest incidence rates of colorectal cancer are found in Australia and New Zealand, Europe, and North America, and the lowest rates are seen in Africa and South and Central Asia. These geographic differences appear to be attributable to differences in dietary and environmental exposures, low socioeconomic status, and lower rates of screening.
It has been recommended that people at average risk of colorectal cancer start regular screening at the age of 45. However, other experts recommend regular screening in average-risk individuals to start no later than at the age of 50. For people with a personal or a family history of colorectal polyps or cancer, or inflammatory bowel disease, screening may need to begin before the age of 45. Men and women should undergo screening since colorectal polyps and cancer affects both genders.

The colorectal cancer can be detected early with the help of several screening options. The screening techniques include the fecal occult blood test (FOBT), flexible sigmoidoscopy, colonoscopy, and computed tomographic colonography. FOBT screening is recommended for colorectal cancer in men and women aged 50 to 74 (The European Union, 2003).
Colorectal cancer may remain symptomless in the early stages. If it does, they may change in bowel habits, diarrhea or constipation, a feeling that the bowel does not empty properly, blood in feces that makes it look dark brown or black, blood from the rectum, abdominal pain and bloating, feeling full, even after a long time since a meal, fatigue or tiredness, unexplained weight loss and anemia.

Around 70 per cent of cases happen for no clear reason, while 10 per cent appear to be inherited and 20 per cent happen in family clusters. Some other associated factors are older age, male, people with a low income, a diet low in fibre and high in animal protein, saturated fats, and calories, a diet high in red or processed meats, alcohol, smoking, and low level of physical activity.
Obesity or overweight, inflammatory bowel disease, type 2 diabetes, certain genetic features, breast, ovary, or uterine cancer history, radiation therapy for abdominal cancer in childhood, and having polyps in the colon or rectum are other risk factors for colorectal cancer. Environmental and genetic factors can increase the likelihood of developing colon cancer. The majority of colorectal cancers are sporadic rather than familial, although familial history results in the most striking increase in the risk.

Lifestyle modifications
Treatment of colorectal cancer depends on several factors. These include the size and location of tumors, the stage of cancer, whether the cancer is recurrent, and the overall health of the person. Chemotherapy, radiation therapy, and surgery are treatment options available. Palliative care has a great role in managing symptoms, such as pain, and thus, improves the quality of life.

Colorectal cancer can affect people of any age, and it is not possible to prevent it. However, some measures may help reduce the risk of developing colon cancer. Dietary measures such as eating plenty of fibre, fruits, and vegetables, eating quality carbohydrates, limiting the intake of red and processed meats, opting for healthy fats, such as avocados, olive oil, fish oils, and nuts may help in the reduction of colorectal cancer.

There is evidence that regular moderate exercise may help lower the risk of colorectal cancer. Exercise can also help reduce the risk of obesity, which is associated with colorectal and other cancers. There is some evidence that taking aspirin may help reduce the risk in some people.

Symptoms of colorectal cancer may not appear until the later stages. When symptoms appear, the severity varies depending on the size of cancer and its location in the large intestine. Anyone with a risk of developing colorectal cancer should consider for screening. Nepal lacks effective screening and prevention strategies, thus, it is urged upon all the stakeholders to initiate regular screening to most at-risk people throughout the country. Early diagnosis and appropriate treatment improve the chances of better outcomes thus greatly reducing cancer mortality.

(Dr. Lohani is the clinical director at the Nepal Drug and Poison Information Centre. lohanis@gmail.com)