Stereotactic body radiation therapy for liver and lung oligometastases from colorectal cancer: safety, local efficacy and prognostic factors / 中华放射肿瘤学杂志

Oligometastasis is an intermediate status between the locally advanced and wide spread disease. Patients with oligometastasis may obtain long-term survival after local treatment. Stereotactic body radiation therapy (SBRT) can deliver radical ablative doses in a small number of fractions, which is a highly precise local ablation therapy. Approximately half of patients diagnosed with colorectal cancer (CRC) will develop metastases, with the liver and lung as the most common site of involvement. In this article, the safety, local efficacy and prognostic factors of SBRT for liver and lung oligometastases from CRC were illustrated. The highlights of SBRT implementation were also discussed. SBRT is safe and effective for oligometastases from CRC under respiratory motion management and robust quality assurance.

Four-dimensional computed tomography scan analysis of liver tumor motion treated with abdominal compression during stereotactic treatment / 中华放射肿瘤学杂志

Objective:To explore the motion and influencing factors of implanted gold markers in guiding liver stereotactic body radiation therapy (SBRT) using abdominal compression.Methods:Twenty patients with oligometastatic colorectal cancer or primary hepatocellular carcinoma from January 2016 to December 2019 were included. All patients were treated with SBRT under abdominal compression, with 1-3 gold markers were implanted within 2 cm from the lesion before positioning. Four-dimensional computed tomography (4DCT) scan was used for treatment planning. The respiratory cycle was divided into 0-90% respiratory phase images based on the respiratory signal, which were reconstructed by the system (Pinnacle 3 version 9.1; Philips Medical System, Madison, WI, USA), and cone beam CT validation images before radiation exposure were obtained. The liver volume was divided into 3 parts: within 2 cm from the main hepatic portal vein, 2-5 cm from the main hepatic portal vein, and>5 cm from the main hepatic portal vein. The motion of different tumor locations was evaluated. Results:The average intrafractional motion amplitude was (2.63±2.81) mm in the cranial-caudal (CC) direction, (1.35±1.23) mm in the anterior-posterior (AP) direction, and (0.76±0.88) mm in the left-right (LR) direction, respectively. The average interfractional motion amplitude was (3.45±3.06) mm, (2.64±2.60) mm, and (2.23±2.07) mm, respectively. Both the intra-or inter-fractional motion amplitudes in the CC direction were the highest, followed by those in the AP and LR direction (all P<0.001). The motion varied at different tumor locations. The longer distance from the main hepatic portal vein, the larger the intrafractional motion (all P<0.05). To cover the 95% population-based confidence interval, the internal target volume (ITV) was suggested to include the expansion of 3.9 mm, 5.2 mm and 7.9 mm in the LR, AP and CC direction. The expansion of 4.3 mm, 4.4 mm and 6.1 mm was delivered within 2 cm from the main hepatic portal vein, and 3.5 mm, 7.3 mm and 9.7 mm>5 cm from the main hepatic portal vein, respectively. The expansion varied significantly depending on the tumor location, whereas the motion in the CC direction was the largest regardless of the tumor location. The longer distance of the tumor from the main portal vein, the larger expansion in the CC direction. The expansion of tumor > 5 cm from the main portal vein in the AP direction was larger than that of inner parts. Conclusion:Liver tumors at different locations require individual external expansion of ITV.

Correlation analysis between MRI parameters and prognosis in locally advanced rectal cancer patients receiving chemoradiotherapy / 中华放射肿瘤学杂志

Objective:To investigate the relationship between MRI parameters and clinical prognosis before and after chemoradiotherapy in patients with locally advanced rectal cancer.Methods:Clinical and follow-up data of 96 patients with locally advanced rectal cancer who were initially treated in the Cancer Hospital of Chinese Academy of Medical Sciences from 2015 to 2017 were retrospectively analyzed. All patients received preoperative chemoradiotherapy, followed by delayed radical surgery at 6-13 weeks after radiotherapy. MRI assessment was performed twice around radiotherapy which were within 4 weeks before the treatment and 4-8 weeks after it. Correlation analysis was utilized to determine the association between MRI assessment and 3-year disease-free survival (DFS).Results:Of the all patients, 80 (83%) had T 3 stage, 16(17%) had T 4 stage, 14 (15%) had N 0 stage, and 82 (86%) had N 1-2 stage. Among them, 69(72%) and 58(60%) patients were positive for MRF and EMVI. The median dose of radiotherapy was 50 Gy, and all patients were sensitized by simultaneous capecitabine. After chemoradiotherapy, T-downstage rate of the whole group was 24%, and 50% for the N-downstage rate. The MRF-and EMVI-positive rates were significantly decreased to 37% and 27% after chemoradiotherapy (both P<0.001). Univariate and multivariate analyses showed that N staging and EMVI status change were significantly correlated with the 3-year DFS. Conclusion:MRI after concurrent chemoradiotherapy reveals that positive EMVI throughout the treatment and N 1-N 2 staing are poor prognostic factors of DFS, suggesting the need for improving the treatment.