Optimal Timing of Surgical Resection After Radiation in Locally Advanced Rectal Adenocarcinoma: An Analysis of the National Cancer Database.

BACKGROUND: In the treatment of rectal cancer, a longer radiation-surgery interval from the end of neoadjuvant radiation therapy to surgery has been associated with higher rates of complete pathologic response (pCR), but the optimal interval with respect to survival has not been established. Data from the National Cancer Database (NCDB) was used to evaluate the impact of radiation-surgery interval on oncologic outcomes. METHODS: The NCDB was searched for patients diagnosed with nonmetastatic rectal cancer who underwent preoperative radiation followed by radical surgical resection. A Cox proportional hazards model was constructed to examine the influence of radiation-surgery interval while controlling for potential confounding factors. Sensitivity analysis was used to confirm the results of the model. RESULTS: A cohort of 6397 patients meeting all inclusion and exclusion criteria from 2004-2006 was identified, and the pCR rate for this cohort was 6.9%. Of those who experienced a pCR, 76.2% had done so by 60 days. Intervals greater than 60 days were associated with higher rates of positive surgical margins (6.7 vs. 4.8%, p = 0.009) and lower rates of sphincter-preserving surgery (64.9 vs. 68.9%, p = 0.007). An interval greater than 60 days was associated with significantly shorter survival (hazard ratio (HR), 1.314; 95% CI 1.191-1.449; p < 0.001). CONCLUSIONS: Radiation-surgery interval beyond 60 days is associated with increased rate of positive surgical margins, decreased rate of sphincter-preserving surgery, and decreased survival. Delay of surgery for rectal cancer beyond 60 days after the completion of neoadjuvant therapy should be done with caution.

Effect of Polyether Ether Ketone on Therapeutic Radiation to the Spine: A Pilot Study.

STUDY DESIGN: Cadaveric model. OBJECTIVES: To compare the effect of PEEK versus conventional implants on scatter radiation to a simulated tumor bed in the spine SUMMARY OF BACKGROUND DATA.: Given the highly vasculature nature of the spine, it is the most common place for bony metastases. After surgical treatment of a spinal metastasis, adjuvant radiation therapy is typically administered. Radiation dosing is primarily limited by toxicity to the spinal cord. The scatter effect caused by metallic implants decreases the accuracy of dosing and can unintentionally increase the effective dose seen by the spinal cord. This represents a dose-limiting factor for therapeutic radiation postoperatively. METHODS: A cadaveric thorax specimen was utilized as a metastatic tumor model with two separate three-level spine constructs (one upper thoracic and one lower thoracic). Each construct was examined independently. All four groups compared included identical posterior instrumentation. The anterior constructs consisted of either: an anterior polyether ether ketone (PEEK) cage, an anterior titanium cage, an anterior bone cement cage (polymethyl methacrylate), or a control group with posterior instrumentation alone. Each construct had six thermoluminescent detectors to measure the radiation dose. RESULTS: The mean dose was similar across all constructs and locations. There was more variability in the upper thoracic spine irrespective of the construct type. The PEEK construct had a more uniform dose distribution with a standard deviation of 9.76. The standard deviation of the others constructs was 14.26 for the control group, 19.31 for the titanium cage, and 21.57 for the cement (polymethyl methacrylate) construct. CONCLUSION: The PEEK inter-body cage resulted in a significantly more uniform distribution of therapeutic radiation in the spine when compared with the other constructs. This may allow for the application of higher effective dosing to the tumor bed for spinal metastases without increasing spinal cord toxicity with either fractionated or hypofractionated radiotherapy. LEVEL OF EVIDENCE: N/A.

The effect of radiation therapy in the treatment of adult soft tissue sarcomas of the extremities: a long-term community-based cancer center experience.

The aim of the study was to determine the effect of external beam radiotherapy (RT) in the treatment of extremity soft tissue sarcoma (STS) before or after limb-sparing surgery (LSS) in a community-based setting. Patients presenting to our institution from 1992 to 2010 and meeting eligibility criteria were stratified into low (G1) or high (G2, G3) pathologic grade and evaluated. Major complication events, including amputation, radiation-induced sarcoma, and pathologic fracture, were assessed. Kaplan-Meier techniques and Cox proportional hazards regression models were used. One hundred and sixty-two eligible patients underwent LSS for extremity STS (120 high grade, 42 low grade). Median time of follow-up was 5.1 years (0.8-20.3 years). RT was administered to 111 patients. In unadjusted models, RT significantly decreased the risk of local recurrence (LR) in high-grade STS patients (P = 0.005) and had a trend for improved recurrence-free survival (RFS) (P = 0.069). In multivariable-adjusted models, RT significantly improved time to LR (P = 0.001), RFS (P = 0.003), and overall survival (OS) (P = 0.003). Analysis of all patients showed those who underwent RT had a major complication rate (MCR) of 16.2%, compared to 3.9% in the no RT group (P = 0.037); however, the difference in MCR did not differ significantly when the analysis was restricted to high-grade sarcomas. In our large experience of patients with extremity STS undergoing limb sparing surgery (LSS), RT significantly improved local recurrence (LR), RFS, and OS, in patients with high-grade tumors. Efficacy benefits of RT should be weighed against potential complications. External beam RT should be considered in patients with resected high-grade sarcomas.