Changing patterns of bone and brain metastases in patients with colorectal cancer

Background: Therapeutic advances for patients with metastatic colorectal cancer (CRC) have been associated with prolonged survival. This study was undertaken to test the hypothesis that expanded treatment options and resultant improved survival for patients with metastatic CRC are associated with an increased incidence of metastases at uncommon sites.

Patients and methods: Patients with metastatic CRC evaluated from 1993 to 2002 at the Fox Chase Cancer Center were identified. Medical records were abstracted to obtain the following: date of diagnosis/metastasis, primary tumor site, therapeutic agents received, survival, and site(s) of metastases.

Results: The records of 1020 patients were reviewed. Incidence of bone and brain metastases were 10.4% (95% CI, 8.6%-12.4%) and 3% (95% CI, 2.2%-4.5%), respectively. Bone metastases were more common with increased numbers of active systemic agents received: 0 (3.7%), 1 (9.4%), 2 (10.9%), 3 (16.3%), and 4/5 (17.4%; P = 0.001; trend test). Patients receiving irinotecan or oxaliplatin were more likely to develop bone metastases (13.2% vs. 8.3%, P = 0.01 for irinotecan; 16.9% vs. 9%, P = 0.003 for oxaliplatin). Patients with primary rectal versus primary colon cancer were more likely to develop bone metastases (16% vs. 8.6%; P = 0.001). Patients with lung metastases were more likely to have bone metastases (16.1% vs. 6.4%; P < 0.0001) or brain metastases (6.2% vs. 1.2%; P < 0.0001) than those without.

Conclusion: These data demonstrate that the incidence of bone and brain metastases in patients with CRC is more common than previously reported and is associated with receipt of multiple systemic treatments. As survival improves for this patient population, clinicians should be aware of the potential for metastases at previously uncommon sites.