Top Line: How does local control influence the risk of widespread progression and survival after SBRT for oligometastatic cancer?
The Study: SBRT does a great job at controlling sites of oligometastatic disease, and in some groups such as NSCLC this translates to improved overall survival. But how strongly does local control influence the risk of subsequent progression or death? This study used a large database of >1000 patients treated with SBRT for >1700 oligometastases to explore the relationship between local tumor control and the subsequent risk of widespread progression and death. Primary sites included NSCLC (25.2%), colorectal (22.7%), prostate (12.8%), and breast (8.1%). Most (57%) had a solitary oligomet and just 8.6% had 4-5 mets. The cumulative rate of local recurrence was 10% at 1 year, 19.6% at 2 years, and 23.9% at 3 years. The respective rates of widespread progression were 24.7%, 36.9%, and 45.1%, and the respective rates of OS were 84.1%, 69.9%, and 56.7%. Patients who had local failure within 6 months of SBRT were at a significantly higher risk (>2x) of subsequent widespread progression and death. They also found that failure at any treated site carried the same risk of progression and death as progression at all treated sites. The authors tested multiple alpha/beta ratios and found that an a/B of 60 was most predictive of local control. A minimum dose of 41.2 Gy in 5 fractions for smaller tumors (<27cc) and 55 Gy in 5 fractions for larger tumors (>27cc) was necessary to achieve a >95% rate of local control.
TBL: This study shows that local control from SBRT for oligometastatic cancer is strongly associated with the subsequent risk of progression and death. It also confirms that minimum dose to the GTV is an important factor in achieving local control. Finally, controlling all known disease is necessary to reduce the risk of progression and death. | Cao, Radiother Oncol 2023
The Study: SBRT does a great job at controlling sites of oligometastatic disease, and in some groups such as NSCLC this translates to improved overall survival. But how strongly does local control influence the risk of subsequent progression or death? This study used a large database of >1000 patients treated with SBRT for >1700 oligometastases to explore the relationship between local tumor control and the subsequent risk of widespread progression and death. Primary sites included NSCLC (25.2%), colorectal (22.7%), prostate (12.8%), and breast (8.1%). Most (57%) had a solitary oligomet and just 8.6% had 4-5 mets. The cumulative rate of local recurrence was 10% at 1 year, 19.6% at 2 years, and 23.9% at 3 years. The respective rates of widespread progression were 24.7%, 36.9%, and 45.1%, and the respective rates of OS were 84.1%, 69.9%, and 56.7%. Patients who had local failure within 6 months of SBRT were at a significantly higher risk (>2x) of subsequent widespread progression and death. They also found that failure at any treated site carried the same risk of progression and death as progression at all treated sites. The authors tested multiple alpha/beta ratios and found that an a/B of 60 was most predictive of local control. A minimum dose of 41.2 Gy in 5 fractions for smaller tumors (<27cc) and 55 Gy in 5 fractions for larger tumors (>27cc) was necessary to achieve a >95% rate of local control.
TBL: This study shows that local control from SBRT for oligometastatic cancer is strongly associated with the subsequent risk of progression and death. It also confirms that minimum dose to the GTV is an important factor in achieving local control. Finally, controlling all known disease is necessary to reduce the risk of progression and death. | Cao, Radiother Oncol 2023