354P - Predictive factors and survival outcomes with stereotactic body radiation therapy in treatment of oligometastases in colorectal cancer

Background

Colorectal cancer (CRC) presents among leading causes of death and oligometastases presents a dilemma in treatment options. If treated, CRC with oligometastases can present improved survival. Our study aims to evaluate predictive factors associated with survival when treated with stereotactic body radiation therapy (SBRT).

Methods

A total of 125 metastases in 50 patients were treated with SBRT. Oligometastases was defined as up to 5 lesions in lung in proven primary histopathology of CRC. Survival outcomes in terms of local control (LC), progression free survival (PFS), and overall survival (OS) were assessed along with association of various predictive factors associated with survival outcomes.

Results

Among the 50 patients, Lung was the most common site of metastases (52.5%), followed by liver (34%). Thirty patients had received prior systemic therapy in form of chemotherapy. Median follow-up time was 24 months (6-84 months). The LC rates at 1, 3 and 5 years were 96%, 72% and 69%, respectively. The first site of failure was local only in 20%, distant only in 34%, and local and distant in 16% of the patients. Median PFS was 9.8 months. The overall survival at 1, 3 and 5 years was 87.2%, 62.3%, and 41.4%, respectively. On assessment of predictive factors, metastases more than 3 cm (p =0.012), presence of non-lung metastases (p < 0.001) and progression of treated metastases (p = 0.021) predicted for worse overall survival.Multiple lung metastases and synchronous oligometastatic disease were significantly associated with worse PFS and worse metastases-free survival. On toxicity assessment, no Grade 3 toxicities were found in the cohort.

Conclusions

Stereotactic body radiation therapy presents longer survival in oligometastases in CRC and is a proven treatment modality. Treatment and control of oligometastases predicts for improved overall survival. Further prospective cohorts would better evaluate effective fractionation for patients with oligometastatic CRC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.