Solitary Brain Metastasis from Early-Onset Colorectal Cancer, Transient Response to Emergency Radiotherapy: A Rare Case Report

<jats:p>Colorectal cancer (CRC) is one of the most common malignancies worldwide, and while metastasis commonly occurs in the liver and lungs, brain metastases from CRC are rare. Solitary brain metastasis in young adults is particularly uncommon. This case report a rare presentation of brain metastasis in a patient with a history of colorectal cancer. Emergency radiotherapy is often considered for symptomatic patients with intracranial hypertension or rapid neurological deterioration, but its benefits may be transient in aggressive tumor biology. We report the case of a 35-year-old male with a history of T3N2bM1a colorectal adenocarcinoma who presented with new-onset neurological symptoms, including headaches and right-sided hemiparesis. CT imaging revealed multiple brain lesions, including solid and hemorrhagic components with erosion of the left frontalis bone and brain edema, suggestive of metastatic disease. Given the rapid neurological decline, the patient was managed with a multidisciplinary approach, including corticosteroids to reduce cerebral edema, followed by whole-brain radiotherapy (WBRT) to address the metastatic lesions. Neurological symptoms improved within days, with partial resolution of hemiparesis. Surgical resection was deferred due to high perioperative risk and patient preference. The clinical improvement was short-lived. Follow-up imaging at 3 months demonstrated lesion progression with increased mass effect, accompanied by worsening neurological function after 4 months. This case highlights the rare occurrence of solitary brain metastasis from CRC in a young patient. It underscores the potential but transient benefit of emergency radiotherapy in rapidly deteriorating neurological states. Early recognition, individualized treatment planning remain essential in optimizing quality of life.</jats:p>