Brain Metastases in Colorectal Cancers

Although colorectal cancer is the most common cancer in Singapore, brain metastases associated with colorectal primaries are quite rare, with reported incidences ranging from less than 1% to 4%. This is a review of the incidence, presentation, and prognosis of brain secondaries from colorectal primaries in our institution.

From a prospectively collected database, 4378 patients underwent surgery for colorectal cancers between 1995 and 2003. Patients who developed brain metastases were identified and their records reviewed retrospectively.

Twenty-seven patients who developed brain metastases were identified, for an incidence of 0.62%. Seventy-one percent of the patients had a tumor in the rectum or sigmoid; 92.6% of patients had metachronous brain secondaries. The median interval between surgery for the primary tumor and the discovery of a brain secondary was 27.5 months. The lung was the most common site of concurrent metastatic disease, with the discovery of a brain secondary a median of 9.7 months after diagnosis of the lung lesion. All patients were symptomatic. The majority of the patients received nonsurgical treatment for the brain lesion. Median survival after diagnosis of brain secondaries was 2.4 months.

The poor survival of the patients in our series could be due to late diagnosis. It may be recommended that a brain scan be performed to screen for a brain secondary when lung and/or liver metastases are discovered, especially in a patient with a left-sided cancer. This may lead to earlier diagnosis, amenability to surgical treatment, and improved survival and quality of life.