Introduction: Colorectal cancer is the third most common cancer in the world. In Singapore, it was the most common cancer in males and second most common cancer in females from 2009 to 2013. The incidence for colorectal cancer is declining, but the mortality remains high. Cancer of the colon is a highly treatable and curable disease when it is localized to the bowel. Timely treatment of cancer, which is defined as the interval between date of diagnosis and starting date of treatment within an assigned time frame, plays an important role for the survival of patients. This is the first study in Southeast Asia looking at multiethnic groups. The study attempts to determine the effect of timely treatment on survival of colorectal cancer patients by using the Singapore cancer registry data.
Methods: Histologically proven colorectal cancer cases of the residents in Singapore diagnosed in 2008-2012 were included. Exclusion criteria for the study were neuroendocrine carcinomas, soft tissue sarcoma, and lymphoma of the bowel. Bivariate analysis was used to describe patient demographic and disease characteristics by survival status of patient as well as by treatment types and stage group. Timely surgery, adjuvant therapy, and neoadjuvant treatment modalities were defined. Cox regression analysis was used to determine the effect of timely treatment on survival of patients by controlling other independent variables of age, sex, the stage of disease, and ethnicity.
Results: A total of 7,739 patients were included in this study. Colorectal cancer was more common in males (55.8%) than in females (44.2%), with a median age of 65.5 years for males and 67.1 years for females. It was more common in Chinese ethnicity (87.7%) followed by Malay (7.4%) and Indian (3.2%). About 40% of patients were diagnosed in early stage and 54.3% in late stage. Primary subsites in order of frequency were sigmoid colon (29%) and rectum (24.4%), followed by rectosigmoid colon (11.4%). About 86% of patients had surgery, of which 47% were treated by surgery alone. More than 75% of patients received timely treatment. Cox regression analysis produced a hazard ratio (HR) of 1.18 (95% CI, 1.02-1.36) for patients who did not receive any type of timely first treatment, an HR of 1.35 (95% CI, 1.17-1.57) for patients with no timely surgery, an HR of 1.4 (95% CI, 1.21-1.62) for patients with no timely adjuvant chemotherapy, and an HR of 2.05 (95% CI, 1.23-3.41) for patients with no timely neoadjuvant therapy.
Conclusion: The study shows that there were significant effects of timely treatment on survival. Information on the timely treatment modalities and its benefits should be included in the public education and emphasized during the treatment planning with patients for better compliance and improved outcomes. Some delays are avoidable and perhaps the causes of these avoidable delays should be identified and resolved to further enhance quality of service in health care.