Dr Sitna Mwanzi, Consultant Medical Oncologist at Aga Khan University Hospital

Colorectal Cancer, a Silent Killer with No Early Warning Symptoms

Colorectal cancer is among the top ten cancers in Kenya. This type of cancer can either start at the colon or the rectum otherwise called the large intestine. According to recent Globocan data, there were 1,354 estimated new cases and 937 deaths from colorectal cancer in 2018 in Kenya. There are probably more cases and deaths from colorectal cancer that were not reported or diagnosed.

Healthy cells in the lining of the colon or rectum can change and grow out of control, forming a mass called a tumour which can be cancerous/malignant or benign. A cancerous/malignant tumour is a tumour that can grow and spread to other parts of the body. A benign tumour means the tumour can grow but will not spread.

Colorectal cancer sometimes begins as a polyp, a non-cancerous growth that may develop on the inner wall of the colon or rectum as people age. If not treated or removed, a polyp can become a potentially life-threatening cancer. Finding and removing pre-cancerous polyps can prevent colorectal cancer.

As with many cancers, age is a risk factor for colon cancer especially for those over 50 years. However, we have encountered cases in younger patients in their 30s and 40s and rarely in their 20s. Other risk factors include a family history of colorectal cancer, changes in the genes, smoking, excessive alcohol intake, poor nutrition, lack of physical activity and obesity. In other cases, no obvious risk factor is identified.

Common symptoms of colorectal cancer include a change in bowel habits with stool thinner than normal, constipation, bright red or very dark blood in the stool, diarrhoea, constant fatigue, and discomfort in the abdomen with bloating and frequent gas pain. When the disease has spread to other organs, other symptoms include weight loss, bone pain, yellowness of eyes and urine amongst others. Anyone with these symptoms lasting for more than 2 weeks should seek medical assistance for evaluation.


Although there is no proven way to completely prevent this disease, one may be able to lower their risk. Observing a diet rich in fruits and vegetables and low in red meat, reducing alcohol intake and smoking cessation are important in reducing the risk of colon cancer. Screening from the age of 50 years under the guidance of a clinician is also recommended. Screening can be done using stool tests and/or colonoscopy to visualise the inside part of the colon. A biopsy which involves the removal of a small amount of tissue for examination under a microscope can make a definite diagnosis of colorectal cancer.

Treatment for colorectal cancer depends on several factors, including the type and stage of cancer, possible side effects, and the patient’s preferences and overall health. Treatment can be in form of surgery to remove the tumour and some surrounding healthy tissue during an operation, radiation therapy, chemotherapy, targeted therapy and immunotherapy which involves the use of materials made either by the body or in a laboratory to boost the body’s natural defenses to fight the cancer. In some cases, a combination of these therapies are used.

Even in the stage where the disease has spread to other organs, treatments are available to shrink the tumour and relieve symptoms for the patient. With the advances in medical therapy, patients with advanced disease are surviving longer and with good quality of life. Throughout the treatment journey, whether in early or advanced disease, it is important to support the patient with his or her physical, emotional, and social needs. Health care costs also need to be addressed.

Just like efforts and resources have been put in place to address breast, cervical and prostate cancers by both public and private stakeholders in healthcare, similar investment for colorectal cancer and emphasis on regular screening is vital for early diagnosis at manageable and treatable stages especially because colorectal cancer may not show any symptoms during the early stages.

Doctors should also be on the lookout for warning signs of colorectal cancer when evaluating patients regardless of their age, to avoid delays in making the correct diagnosis and early treatment.

By Dr Sitna Mwanzi, Consultant Medical Oncologist at Aga Khan University Hospital