In a nutshell
This article summarized what is known about colorectal cancer: age groups most at risk, nationalities most at risk, treatment and prevention.
Some background
Colorectal cancer is the third most common cancer worldwide and an important cause of cancer related death. Roughly 1.2 million new cases are diagnosed and 600,000 people die from colorectal cancer each year. It is more likely to occur in older individuals; the average age at diagnosis is 70 years. The rate of colorectal cancer is highest in Europe, North America and Oceania (includes Micronesia, Fiji and Polynesia). To reduce the mortality rate for patients it is important to pinpoint markers that can predict patient outcome (prognosis) and the best treatment option.
Methods & findings
This article examined 134 papers and summarized some of their most important findings. Two of the main focuses of the article were: markers of prognosis and treatment strategies.
Markers of prognosis
A number of laboratory measurements can be useful for predicting patient outcome and if treatment will be successful. Initially the stage (describes the extent and severity of the cancer) and grade (describes how abnormal tumor cells look under the microscope) of the cancer should be determined. Patients with more aggressive tumors that have spread through the bowel, to lymph nodes (stage III) or distant organs (stage IV) have a worse prognosis. Increased numbers of immune cells around the tumor predicts better patient outcome. This is irrespective of the stage of the cancer.
Genetic markers are often examined in patients. One of the most commonly mutated (abnormal) genes in colorectal cancer patients is KRAS. Patients with mutated KRAS do not respond to some drug treatments.
Certain patients will have tumors that have abnormally high rates of mutation, this is known as microsatellite instability (MSI). Patients with MSI-high tumors have a better prognosis but may not respond well to some chemotherapy.
Treatment strategies
Surgery is the most common curative treatment for colorectal cancer. Originally the only option was open surgery (a large incision into the abdomen), now laparoscopic surgery (smaller incision) also exists. Laparoscopic surgery reduces the blood loss during surgery and improves the recovery time for patients. However, the surgery takes longer and is more costly.
Some patients receive radiotherapy or chemoradiotherapy (chemotherapy and radiotherapy) before surgery (neoadjuvant therapy). Neoadjuvant therapy is used for patients who have higher risk cancers to shrink their tumors before surgery. This decreases the risk of the cancer returning (recurrence) after surgery. Chemotherapy after surgery is also recommended for patients with stage III colon cancer as it can reduce the chance of recurrence. Some patients with higher risk stage II colon cancer can also benefit from chemotherapy after surgery.
The bottom line
The authors reported that colorectal cancer remains one of the most common causes of cancer related death worldwide. However, prognosis has improved in the last decade due to improved treatment and early detection.
