Personalising colorectal cancer treatment
Colorectal cancer is a cancer that starts in the colon or the rectum. The colon and rectum make up the large intestine. There is a rising incidence of this cancer in India, especially in the metropolitan cities - 55,000 new cases are diagnosed each year. This is attributed to lifestyle factors including being overweight, lack of physical activity, or a diet with red meat, junk food and lack of fruits and vegetables. Smokers and alcoholics are likely to develop colorectal cancer. Although average age for developing this cancer is 50 to 60 years, more cases are being seen at 25 to 30 years. The common symptoms of colorectal cancer are blood in stools, diarrhea or constipation and vague abdominal complaints.
Early diagnosis can cure over 80 to 90% of cases and thus screening tests are recommended after the age of 40 years annually. Stool-based tests looking for presence of hidden blood is carried fecal occult blood test (FOBT).
Screening colonoscopy is recommended only in high risk cases viz, persons with family history of colon cancer. Biopsy test is mandatory to confirm the diagnosis. Once the diagnosis is confirmed, CT scans of chest and abdomen are done for staging. Depending on the stage of the cancer, treatment is advised. In early stages, patients are usually managed with surgery followed by 3 to 6 months of adjuvant chemotherapy and or radiotherapy (for rectum cancer). The cure rates in early stages exceed 80%. In advanced stages, cancer chemotherapy and targeted therapy are the mainstay of therapy. Molecular tests of genes like K ras, N ras, and B raf are required to select the targeted drugs like bevacizumab/cetuximab. Several treatment lines are carried in a sequential fashion to improve quality of life and longevity to convert this disease into a chronic ailment ( greater than 3 to 4 years ). Next generation sequencing and immunotherapy are new treatment options for these patients. Finally, patients with liver- only metastasis are considered potentially curable if radical surgery is done. Thus, there is lot of hope today for patients diagnosed with colorectal cancer.