Stereotactic body radiation therapy for melanoma and renal cell carcinoma: impact of single fraction equivalent dose on local control

<p>Abstract</p> <p>Background</p> <p>Melanoma and renal cell carcinoma (RCC) are traditionally considered less radioresponsive than other histologies. Whereas stereotactic body radiation therapy (SBRT) involves radiation dose intensification via escalation, we hypothesize SBRT might result in similar high local control rates as previously published on metastases of varying histologies.</p> <p>Methods</p> <p>The records of patients with metastatic melanoma (n = 17 patients, 28 lesions) or RCC (n = 13 patients, 25 lesions) treated with SBRT were reviewed. Local control (LC) was defined pathologically by negative biopsy or radiographically by lack of tumor enlargement on CT or stable/declining standardized uptake value (SUV) on PET scan. The SBRT dose regimen was converted to the single fraction equivalent dose (SFED) to characterize the dose-control relationship using a logistic tumor control probability (TCP) model. Additionally, the kinetics of decline in maximum SUV (SUV_max) were analyzed.</p> <p>Results</p> <p>The SBRT regimen was 40-50 Gy/5 fractions (n = 23) or 42-60 Gy/3 fractions (n = 30) delivered to lung (n = 39), liver (n = 11) and bone (n = 3) metastases. Median follow-up for patients alive at the time of analysis was 28.0 months (range, 4-68). The actuarial LC was 88% at 18 months. On univariate analysis, higher dose per fraction (p < 0.01) and higher SFED (p = 0.06) were correlated with better LC, as was the biologic effective dose (BED, p < 0.05). The actuarial rate of LC at 24 months was 100% for SFED ≥45 Gy v 54% for SFED <45 Gy. TCP modeling indicated that to achieve ≥90% 2 yr LC in a 3 fraction regimen, a prescription dose of at least 48 Gy is required. In 9 patients followed with PET scans, the mean pre-SBRT SUV_maxwas 7.9 and declined with an estimated half-life of 3.8 months to a post-treatment plateau of approximately 3.</p> <p>Conclusions</p> <p>An aggressive SBRT regimen with SFED ≥ 45 Gy is effective for controlling metastatic melanoma and RCC. The SFED metric appeared to be as robust as the BED in characterizing dose-response, though additional studies are needed. The LC rates achieved are comparable to those obtained with SBRT for other histologies, suggesting a dominant mechanism of in vivo tumor ablation that overrides intrinsic differences in cellular radiosensitivity between histologic subtypes.</p

Association of Radiotherapy Duration With Clinical Outcomes in Patients With Esophageal Cancer Treated in NRG Oncology Trials: A Secondary Analysis of NRG Oncology Randomized Clinical Trials

IMPORTANCE: For many types of epithelial malignant neoplasms that are treated with definitive radiotherapy (RT), treatment prolongation and interruptions have an adverse effect on outcomes. OBJECTIVE: To analyze the association between RT duration and outcomes in patients with esophageal cancer who were treated with definitive chemoradiotherapy (CRT). DESIGN, SETTING, AND PARTICIPANTS: This study was an unplanned, post hoc secondary analysis of 3 prospective, multi-institutional phase 3 randomized clinical trials (Radiation Therapy Oncology Group [RTOG] 8501, RTOG 9405, and RTOG 0436) of the National Cancer Institute-sponsored NRG Oncology (formerly the National Surgical Adjuvant Breast and Bowel Project, RTOG, and Gynecologic Oncology Group). Enrolled patients with nonmetastatic esophageal cancer underwent definitive CRT in the trials between 1986 and 2013, with follow-up occurring through 2014. Data analyses were conducted between March 2022 to February 2023. EXPOSURES: Treatment groups in the trials used standard-dose RT (50 Gy) and concurrent chemotherapy. MAIN OUTCOMES AND MEASURES: The outcomes were local-regional failure (LRF), distant failure, disease-free survival (DFS), and overall survival (OS). Multivariable models were used to examine the associations between these outcomes and both RT duration and interruptions. Radiotherapy duration was analyzed as a dichotomized variable using an X-Tile software to choose a cut point and its median value as a cut point, as well as a continuous variable. RESULTS: The analysis included 509 patients (median [IQR] age, 64 [57-70] years; 418 males [82%]; and 376 White individuals [74%]). The median (IQR) follow-up was 4.01 (2.93-4.92) years for surviving patients. The median cut point of RT duration was 39 days or less in 271 patients (53%) vs more than 39 days in 238 patients (47%), and the X-Tile software cut point was 45 days or less in 446 patients (88%) vs more than 45 days in 63 patients (12%). Radiotherapy interruptions occurred in 207 patients (41%). Female (vs male) sex and other (vs White) race and ethnicity were associated with longer RT duration and RT interruptions. In the multivariable models, RT duration longer than 45 days was associated with inferior DFS (hazard ratio [HR], 1.34; 95% CI, 1.01-1.77; P = .04). The HR for OS was 1.33, but the results were not statistically significant (95% CI, 0.99-1.77; P = .05). Radiotherapy duration longer than 39 days (vs ≤39 days) was associated with a higher risk of LRF (HR, 1.32; 95% CI, 1.06-1.65; P = .01). As a continuous variable, RT duration (per 1 week increase) was associated with DFS failure (HR, 1.14; 95% CI, 1.01-1.28; P = .03). The HR for LRF 1.13, but the result was not statistically significant (95% CI, 0.99-1.28; P = .07). CONCLUSIONS AND RELEVANCE: Results of this study indicated that in patients with esophageal cancer receiving definitive CRT, prolonged RT duration was associated with inferior outcomes; female patients and those with other (vs White) race and ethnicity were more likely to have longer RT duration and experience RT interruptions. Radiotherapy interruptions should be minimized to optimize outcomes

Stereotactic Body Radiation Therapy

XXV, 421 p. 120 illus. in color.online resource

Should we customize PTV expansions for BMI? Daily cone beam computerized tomography to assess organ motion in postoperative endometrial and cervical cancer patients

AimA single-institution review assessing patient characteristics contributing to daily organ motion in postoperative endometrial and cervical cancer patients treated with intensity-modulated radiotherapy (IMRT).BackgroundThe Radiation Therapy Oncology Group has established consensus guidelines for postoperative pelvic IMRT, recommending a 7[[ce:hsp sp="0.25"/]]mm margin on all three axes of the target volume.Materials and methodsDaily shifts on 457 radiation setups for 18 patients were recorded in the x axis (lateral), y axis (superior–inferior) and z axis (anterior–posterior); daily positions of the planning tumor volume were referenced with the initial planning scan to quantify variations.ResultsOf the 457 sessions, 85 (18.6%) had plan shifts of at least 7[[ce:hsp sp="0.25"/]]mm in one of the three dimensions. For obese patients (body mass index [BMI][[ce:hsp sp="0.25"/]]≥[[ce:hsp sp="0.25"/]]30), 75/306 (24.5%) sessions had plan shifts ≥7[[ce:hsp sp="0.25"/]]mm. Odds of having a shift ≥7[[ce:hsp sp="0.25"/]]mm in any direction was greater for obese patients under both univariate (OR 4.227, 95% CI 1.235–14.466, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.021) and multivariate (OR 5.000, 95% CI 1.341–18.646, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.016) analyses (MVA). Under MVA, having a BMI[[ce:hsp sp="0.25"/]]≥[[ce:hsp sp="0.25"/]]30 was associated with increased odds of shifts in the anterior–posterior (1.173[[ce:hsp sp="0.25"/]]mm, 95% CI 0.281–2.065, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.001) and lateral (2.074[[ce:hsp sp="0.25"/]]mm, 95% CI 1.284–2.864, p[[ce:hsp sp="0.25"/]

Clinical and Dosimetric Impact of 2D kV Motion Monitoring and Intervention in Liver Stereotactic Body Radiation Therapy

Purpose: Positional errors resulting from motion are a principal challenge across all disease sites in radiation therapy. This is particularly pertinent when treating lesions in the liver with stereotactic body radiation therapy (SBRT). To achieve dose escalation and margin reduction for liver SBRT, kV real-time imaging interventions may serve as a potential solution. In this study, we report results of a retrospective cohort of liver patients treated using real-time 2D kV-image guidance SBRT with emphasis on the impact of (1) clinical workflow, (2) treatment accuracy, and (3) tumor dose. Methods and Materials: Data from 33 patients treated with 41 courses of liver SBRT were analyzed. During treatment, planar kV images orthogonal to the treatment beam were acquired to determine treatment interventions, namely treatment pauses (ie, adequacy of gating thresholds) or treatment shifts. Patients were shifted if internal markers were >3 mm, corresponding to the PTV margin used, from the expected reference condition. The frequency, duration, and nature of treatment interventions (ie, pause vs shift) were recorded, and the dosimetric impact associated with treatment shifts was estimated using a machine learning dosimetric model. Results: Of all fractions delivered, 39% required intervention, which took on average 1.9 ± 1.6 minutes and occurred more frequently in treatments lasting longer than 7 minutes. The median realignment shift was 5.7 mm in size, and the effect of these shifts on minimum tumor dose in simulated clinical scenarios ranged from 0% to 50% of prescription dose per fraction. Conclusion: Real-time kV-based imaging interventions for liver SBRT minimally affect clinical workflow and dosimetrically benefit patients. This potential solution for addressing positional errors from motion addresses concerns about target accuracy and may enable safe dose escalation and margin reduction in the context of liver SBRT

A phase II study of neoadjuvant therapy with cisplatin, docetaxel, panitumumab plus radiation therapy followed by surgery in patients with locally advanced adenocarcinoma of the distal esophagus (ACOSOG Z4051)

4062 Background: Multiple clinical trials have incorporated preoperative chemotherapy and radiation (RT) in an attempt to improve local tumor control, distant disease failure and overall survival rates for locally advanced but resectable adenocarcinoma of the distal esophagus and gastroesophageal junction (GEJ). This multicenter, cooperative group study combined active chemotherapy agents cisplatin (C), docetaxel (D) and the targeted EGFR agent panitumumab (P) in the induction phase followed by concurrent chemotherapy (CDP) and radiation. Pathologic complete response (pCR), a surrogate for improved survival, was the primary endpoint. Methods: From 01/15/09 to 07/22/11, 70 patients (pts) with Siewert I or II adenocarcinomas and clinical stages T3N0M0, T2-3N1M0 or T2-3N0-1M1a (celiac LN ≤ 2 cm) were accrued. Patients received cisplatin (40 mg/m2), docetaxel (40 mg/m2) and panitumumab (6 mg/kg) on weeks 1, 3, 5, 7, 9 with RT (5040 cGy, 180 cGy/day x 28d) beginning week 5. The decision rule had a 90% power with a 0.10 significance level to detect a pCR rate of at least 35%. Secondary objectives included near-pathologic complete response (near-pCR), toxicity, and overall and disease-free survival rates. Results: Five pts were ineligible. Of the remaining 65 pts (59 M, 6 F; median age 61), 12 pts did not undergo surgery (5 progressed, 4 refused, 3 other). Of the 58 evaluable pts, the pCR rate was 32.8% (90% CI: 22.6% -42.9%) and near-pCR 22.4% (90% CI: 13.4%-31.4%). Total doses of C, D, and P were achieved in 76%, 80%, and 73%, respectively (n = 70). 66 pts (94%) received the total RT dose. Sixteen pts (23%) had a grade 4+ non-heme adverse event possibly related to treatment. Venous thrombosis (5 pts) was most common. Conclusions: The CDP regimen in the neoadjuvant setting in patients with esophageal adenocarcinomas is active (pCR + near-pCR = 55.2%) and feasible. The toxicity though tolerable is substantial