Conventional MRI does not reliably distinguish radiation necrosis from tumor recurrence after stereotactic radiosurgery

Distinguishing radiation necrosis (RN) from tumor recurrence after stereotactic radiosurgery (SRS) for brain metastases is challenging. This study assesses the sensitivity (SN) and specificity (SP) of an MRI-based parameter, the "lesion quotient" (LQ), in characterizing tumor progression from RN. Records of patients treated with SRS for brain metastases between 01/01/1999 and 12/31/2009 and with histopathologic analysis of a subsequent contrast enhancing enlarging lesion at the treated site at a single institution were examined. The LQ, the ratio of maximal nodular cross sectional area on T2-weighted imaging to the corresponding maximal cross sectional area of T1-contrast enhancement, was calculated by a neuroradiologist blinded to the histopathological outcome. Cutoffs of <0.3, 0.3-0.6, and >0.6 have been previously suggested to have correlated with RN, mixed findings and tumor recurrence, respectively. These cutoff values were evaluated for SN, SP, positive predictive value (PPV) and negative predictive value (NPV). Logistic regression analysis evaluated for associated clinical factors. For the 51 patients evaluated, the SN, SP, PPV and NPV for identifying RN (LQ < 0.3) were 8, 91, 25 and 73 %, respectively. For the combination of recurrent tumor and RN (LQ 0.3-0.6) the SN, SP, PPV and NPV were 0, 64, 0 and 83 %. The SN, SP, PPV and NPV of the LQ for recurrent tumor (LQ > 0.6) were 59, 41, 62 and 39 %, respectively. Standard MRI techniques do not reliably discriminate between tumor progression and RN after treatment with SRS for brain metastases. Additional imaging modalities are warranted to aid in distinguishing between these diagnoses.

Marginal recurrence requiring salvage radiotherapy after stereotactic body radiotherapy for spinal metastases

INTRODUCTION

We sought to quantify and identify risk factors associated with margin recurrence (MR) requiring salvage radiotherapy after stereotactic body radiation therapy (SBRT) for spinal metastases.

METHODS

We retrospectively reviewed patients with spinal metastases who were treated with single-fraction SBRT between 2006 and 2009. Gross tumor was contoured, along with either the entire associated vertebral body(ies) or the posterior elements, and included in the planning target volume. No additional margins were used. MR was defined as recurrent tumor within one vertebral level above or below the treated lesion that required salvage radiotherapy. Only patients who presented for 3-month post-SBRT follow-up were included in the analysis. Fine and Gray competing risk regression models were generated to identify variables associated with higher risks of MR. MR was plotted using cumulative incidence analysis.

RESULTS

SBRT was delivered to 208 lesions in 149 patients. Median follow-up was 8.6 months, and median survival was 12.8 months. The median prescribed dose was 14 Gy (10-16 Gy). MR occurred in 26 (12.5%) treated lesions, at a median time of 7.7 months after SBRT. Patients with paraspinal disease at the time of SBRT (20.8% vs. 7.6% of patients; p = 0.02), and those treated with <16 Gy (16.3% vs. 6.3% of patients, p = 0.14) had higher rates of MR. Both variables were associated with significantly higher risk of MR on multivariate analysis.

CONCLUSION

SBRT for spinal metastases results in a low overall rate of MR. The presence of paraspinal disease at the time of SBRT and a dose of <16 Gy were associated with higher risks of MR.

Stereotactic radiosurgery for single brainstem metastases: the cleveland clinic experience

PURPOSE

To assess the imaging and clinical outcomes of patients with single brainstem metastases treated with stereotactic radiosurgery (SRS).

MATERIALS AND METHODS

We retrospectively reviewed the data from patients with single brainstem metastases treated with SRS. Locoregional control and survival were calculated using the Kaplan-Meier method. Prognostic factors were assessed using a Cox proportional hazards model.

RESULTS

Between 1997 and 2007, 43 patients with single brainstem metastases were treated with SRS. The median age at treatment was 59 years, the median Karnofsky performance status was 80, and the median follow-up was 5.3 months. The median dose was 15 Gy (range, 9.6-24), and the median conformality and heterogeneity index was 1.7 and 1.9, respectively. The median survival was 5.8 months from the procedure date. Of the 33 patient with post-treatment imaging available, a complete radiographic response was achieved in 2 (4.7%), a partial response in 8 (18.6%), and stable disease in 23 (53.5%). The 1-year actuarial rate of local control, distant brain control, and overall survival was 85%, 38.3%, and 31.5%, respectively. Of the 43 patients, 8 (19%) died within 2 months of undergoing SRS, and 15 (36%) died within 3 months. On multivariate analysis, greater performance status (hazard ratio [HR], 0.95, p = .004), score index for radiosurgery (HR, 0.7; p = .004), graded prognostic assessment score (HR, 0.48; p = .003), and smaller tumor volume (HR, 1.23, p = .002) were associated with improved survival. No Grade 3 or 4 toxicities were observed.

CONCLUSION

The results of our study have shown that SRS is a safe and effective local therapy for patients with brainstem metastases.

Risks and benefits associated with novel phase 1 oncology trial designs

BACKGROUND

Although aggressive dose escalation strategies were designed to improve the risk-benefit profile of phase 1 oncology trials, they have not been adequately studied. The prevalence of several novel trial designs and their association with a variety of clinical endpoints was evaluated.

METHODS

A review of the literature was performed to identify phase 1 oncology studies of cytotoxic agents published from 2002 through 2004.

RESULTS

Of 955 phase 1 oncology articles initially identified, 149 studies, comprising 4532 patients, were analyzed. Only 34% of studies utilized aggressive dose escalation schemes, 22% permitted intrapatient dose escalation, and only 28% enrolled fewer than 3 patients to any dose level. Studies that allowed intrapatient dose escalation or used fewer than 3 patients per dose were not associated with different rates of response or toxicity, nor did they increase the number of patients who received the recommended phase 2 dose. However, aggressive dose escalations were associated with increased rates of both hematologic (17% vs 10%) and nonhematologic (17% vs 13%) toxicity with similar response rates. Only studies that used conservative dose escalation designs and those that studied U.S. Food and Drug Administration (FDA)-approved agents required fewer patients to complete a trial. Trials of FDA-approved agents were also associated with higher response rates than trials of non-FDA-approved agents (10% vs 2%), without an increased risk of toxicity.

CONCLUSIONS

Several novel aggressive design strategies intended to improve the risk-benefit profile of phase 1 oncology trials are not associated with improved clinical outcome, and may be harmful in certain instances.

Adenoid cystic carcinoma of the cervix

BACKGROUND

Adenoid cystic carcinoma of the cervix is a rare and aggressive neoplasm for which there are no standardized treatment protocols.

CASE

A 38-year-old G3P3 Asian female diagnosed with a stage Ib adenoid cystic carcinoma of the cervix with intermediate risk histologic features received a type III hysterectomy in July 2004. She refused external beam radiotherapy, but agreed to be treated with adjuvant vaginal cuff radiation. She has been closely followed and has no evidence of disease to date.

CONCLUSION

Patients with stage Ib adenoid cystic carcinoma of the cervix, especially those with histologic features associated with a higher risk of recurrence, should receive aggressive local therapy, following the guidelines established for similarly staged patients with squamous cell carcinoma of the cervix.