Oligometastatic Colorectal Cancer: is Single-site Bony Colorectal Metastasis a Treatable Condition?

Introduction: A potentially resectable bony metastasis in the context of oligometastatic colorectal cancer is uncommon. Bony metastases are usually considered a late event with poor prognosis and generally associated with liver and/or lung metastases.

Index Case: A previously healthy 33-year-old gentleman, with no family history of colorectal cancer, presented with rectal bleeding and at colonoscopy had a biopsy-proven adenocarcinoma of the rectum, 7 cm from the anal verge. Imaging also showed an isolated bone metastasis in the left ischial tuberosity. Following recovery from an anterior resection and a segment 5 metastasectomy, he underwent resection of the bony metastasis with a left type 3 internal hemipelvectomy. Three years from the bony resection, there is no evidence of recurrence on imaging.

Discussion: Osseous metastases are usually treated with palliative intent with bisphosphonates or external radiation, with surgical fixation of pathological fractures in some cases. Median survival after diagnosis of bone metastases is less than 10 months. Surgery is perhaps the only way of potentially achieving cure in patients with single-site bony metastases from colorectal cancer. Reports of such surgery in the literature are however very scant.

Conclusion: Our case is unusual and ongoing follow up is required. However, current disease-free status at conventional and functional imaging is encouraging. A multidisciplinary and indeed multicentre approach may be needed, and oligometastatic disease, even to a bone, may be amenable to curative surgical intervention in highly selected cases.