This study provided estimates of survival time and identified prognostic factors of colorectal cancer patients in the only oncology referral center in Ethiopia over the period 2012–2016. Our findings revealed that the median age at diagnosis was 46 and 52.8% of them are diagnosed age less than 50, which shows majority of them are young adults and middle aged adults whereas the median age at diagnosis was 70 in Germany. Data from Oman showed that the median age was 56 years and majority of the patients, 61.1%, were older than 50 years. Similarly, in Jordan the median age was 62 for males and 58 for females. More than half of the patients were above age 60 years, which differs from our study result. The contributing factors are age structure of Ethiopia. It might also relate to the unhealthy nutritional habit in Ethiopia (high intake of fats and red meats) and lack of birth registration may contribute as most patients from rural area might not know their exact age. (22, 24, 26)
Around 34% of the patients were metastatic cancer at presentation. This is similar to a report from Oman (36.8) and Kenya (29.1%) but in contrast with reports from Germany (28.1%), in Ghana (24.9%), in Malaysia (24.3%), in Jordan (17.2%) and in Iran (6.8%) of patients were metastatic.(15, 18, 21, 22, 24, 26, 29) The late presentation might be due to patients’ low awareness of colorectal cancer sign and symptoms, lack of screening program, lengthy and poor referral system in Ethiopia. This might have contributed to the observed low survival of patients treated in Tikur Anbesa Specialized hospital in Addis Ababa, Ethiopia.
In our current study, the five year overall survival (OS) rate was 33%, much lower than OS rate in developed countries. Highest five-year survival rate (72%) are in Israel and North Korea. Survival varies from 65% to 70% in North America, Europe and Australia, 63% in Germany and 55% in other developed countries.(13, 14, 26) This could be primarily due to increase in colorectal cancer screening, removal of precancerous adenomas, timely and advanced treatment in developed countries. In developing Asian countries, the five-year survival rate of CRC patients ranged from 33% to 56.9% in Iran, 58.2% in Jordan, 43% & 48.7% in Malaysia, 42% in Oman, 39% in India, 38.6% in Thailand which are above the survival rate of patients in Ethiopia. (14, 15, 18, 22–25, 27, 29) The reason for this difference could be lack of screening programs to detect the cancer at an early stage, poorly developed infrastructure of cancer health cares in Ethiopia. Treatments are also very limited and inaccessible especially for patients living far from TASH, the only oncology and cancer referral center in the country. The five years overall survival rates of colorectal cancer patients in a teaching hospital in Ghana (n = 221) was 16% which is below the overall survival rate in this study.(21) Variation in methodology, population characteristics and observed number of events may have contributed to these differences in findings.
In our study, age at diagnosis is not a significant prognostic factor affecting survival. This is consistent with studies conducted in Malaysia and Ghana(15, 21). However, it was inconsistent with studies conducted in India, Iran, Jordan and Thailand. (17, 18, 20, 22, 25) This might be due to the fact that majority of the study participant were young compared to patients in those studies. Comorbidity is not also a significant prognostic factor affecting patient’s survival. This finding is also in line with reports from Ghana, Iran and Malaysia. (15, 21, 23)
In multivariable Cox regression model, Primary tumor site (P <0.05), lymph node involvement (P <0.01), distant metastasis (P <0.001) and treatment modalities (p< 0.01) were significant prognostic factors for colorectal cancer patients survival. Patients diagnosed with rectal cancer had 76% (HR = 1.761) increased hazard to death compared to colon cancer patients. This is in agreement with reports from Iran where rectal cancer had high risk of death and determines prognosis significantly.(18)
In this study, the hazard of death was significantly higher for those patients who were diagnosed with positive lymph node with (HR = 3.146) compared to node negative. This finding is in line with reports from Ghana, Malaysia, Thailand and Iran.(15, 18, 21, 25) The other finding of this study is the risk of death was four fold higher (HR = 4.221) for those who presented with metastatic cancer compared to non-metastatic cancer patients. This finding is comparable to those reports found in Ghana, Thailand, Jordan, Malaysia and Iran.(15, 18, 21, 22, 25) Node involvement and metastatic cancer at presentation were the major prognostic factors for colorectal cancer patients.
The finding of this study demonstrates that risk of death was significantly lesser (HR = 0.639 &0.521) among those who received adjuvant chemotherapy or/and adjuvant radiotherapy compared to those who only received surgical resection. This is similar to reports from Ghana, Thailand, Iran and Malaysia that adjuvant therapy was a good prognostic factor. (15, 18, 21, 25)
The study was conducted in the only oncology referral center in the country that provides services for majority of cancer cases from all over the country. Hence, our findings may reflect the situation in the whole of Ethiopia. The limitations of this study are possible significant prognostic factors such as family history, lymphovascular invasion; perinural invasion and pre-operative CEA level were not assessed due to the scantiness of the data. The other limitation is that only seven CRC patients died in the institution with a report of detailed causes of death. The death of the remaining 168 patients and causes of deaths were ascertained by telephone interview not from death report which may lead to over detection of death as a result of cause ascertainment bias.