Predicting the benefit of stereotactic body radiotherapy of colorectal cancer metastases

Sara Lindberg; Eva Onjukka; Peter Wersäll; Caroline Staff; Rolf Lewensohn; Giuseppe Masucci; Karin Lindberg

doi:10.1016/j.ctro.2022.07.006

Predicting the benefit of stereotactic body radiotherapy of colorectal cancer metastases

Clin Transl Radiat Oncol. 2022 Jul 21:36:91-98. doi: 10.1016/j.ctro.2022.07.006. eCollection 2022 Sep.

Authors

Sara Lindberg^{1

2}, Eva Onjukka^{1

3}, Peter Wersäll^{1

4}, Caroline Staff⁵, Rolf Lewensohn^{1

2}, Giuseppe Masucci^{1

2}, Karin Lindberg^{1

2}

Affiliations

¹ Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden.
² Section of Head, Neck, Lung and Skin Tumours, Theme Cancer, Karolinska University Hospital, Stockholm, Sweden.
³ Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.
⁴ Department of Radiotherapy, Karolinska University Hospital, Stockholm, Sweden.
⁵ Capio St. Göran Hospital, Stockholm, Sweden.

Abstract

Aim: To evaluate Stereotactic body radiotherapy (SBRT) in metastatic colorectal cancer (mCRC) and identify the benefit of the treatment by using a predictive algorithm.

Methods: 85 patients treated with SBRT for mCRC were retrospectively analyzed. The CLInical Categorical Algorithm (CLICAL©) was used to predict probability of relapse after SBRT. Variables pre-SBRT were tested for significance for time to relapse (TTR). The patients' CLICAL© score was the mean of sub-scores of each significant variable's effect on the endpoint. Patients with similar scores were grouped into four signatures dependent on level of benefit after SBRT.

Results: Median age was 69 years (42-88), 63 % had a performance status 0 and 47 % were treated for a single metastasis. At the time of the analysis, 90 % had relapsed (95 % out-of-field). Median TTR was 7.3 months (4.6-8.5), and the 2-year relapse-free rate was 15 % (95 %CI = 7-22). The CLICAL© signature III-IV predicted a low risk of relapse if receiving high dose SBRT to all metastases or to lung metastases only. Signature I-II had a short TTR, why SBRT for these patients was judged non-beneficial.

Conclusion: The benefit from SBRT varies among mCRC patients. CLICAL© may serve as a screening tool for SBRT referrals but needs to be validated.