PurposeComputed tomography (CT) is inferior to magnetic resonance imaging (MRI) in cervical tumor delineation, but similar in identification of organs at risk (OAR). The trend to over-estimate high-risk and low-risk clinical target volume (HRCTV, IRCTV) on CT can lead to under-estimation of dose received by 90% (D90) of the ‘actual’ CTV. This study aims to evaluate whether CT-guided planning delivers adequate dose to the ‘actual’ targets while spares the OAR similarly.Material and methodsMRI-guided high-dose-rate image-guided brachytherapy (IGBT) was performed in 11 patients. The pre-brachytherapy CTs were retrospectively contoured to generate CT-guided plans. MRI-based contours (HRCTVmri, IRCTVmri, bladdermri, rectummri, and sigmoidmri) were fused to CT plans for dosimetric comparison with MRI-guided plans. Paired 2-tailed t-test and Wilcoxon signed-rank test were used to analyze data.Results63.6% of CT plans achieved the HRCTVmriD90 constraint (≥ 7.2 Gy in one fraction), compared with 90.9% for MRI plans. > 90% of both modalities achieved the OAR’s constraints (EMBRACE). The percentage of CT and MRI plans that achieved the aims (EMBRACE II) for bladder, rectum, and sigmoid were 36.4% vs. 81.8%, 63.6% vs. 63.6%, and 72.7% vs. 72.7%, respectively. There were no statistically significant differences in HRCTVmriD90, IRCTVmriD90, or dose received by the most exposed 2 cm3 (D2cc) of OARmri between the modalities. Excluding the CT plans not achieving HRCTVmriD90 constraint, there were significant increase in bladdermriD2cc, rectummriD2cc, and sigmoidmriD2cc, compared with MRI plans (0.9 Gy/Fr, 95% CI 0.2-1.5, p = 0.018; 0.9 Gy/Fr, 95% CI 0.3-1.4, p = 0.009; 0.5 Gy/Fr, 95% CI 0.2-0.9, p = 0.027, respectively).ConclusionsMRI-based IGBT remains the gold standard. CT planning may compromise HRCTVmriD90 or increase OARmriD2cc, which could decrease local control or increase treatment toxicity.
The optimal timing of chemoradiotherapy (CRT) in patients with gastric cancer remains unclear. We sought to compare the survival outcomes between neoadjuvant CRT (NCRT) vs. postoperative CRT (postCRT) in patients with gastric cancer. We hypothesized that NCRT would be associated with better survival compared to postCRT. Materials/Methods: We retrospectively reviewed patients with gastroesophageal junction (GEJ) or gastric adenocarcinoma who underwent surgical resection and NCRT or postCRT between 2005-2017 at a single institution. Clinical parameters such as sex, age, performance status, histology, stage, surgical outcomes, chemotherapy (CTX), and radiotherapy (RT) regimen were analyzed. CRT-related toxicity was graded according to CTCAE v5.0. The primary endpoint was overall survival (OS), assessed from the time of diagnosis. Survival analysis was conducted using Cox proportional hazards regression and Kaplan Meier estimates. Results: We identified 152 patients, and median follow-up was 37.5 months. Median age was 63. 77% were male. 93% had an ECOG <2. Tumor location was gastroesophageal junction (GEJ) in 58% and gastric in 42%. Clinical stage was mostly II (44%) or III (44%). 102 (67%) patients underwent NCRT while 50 (33%) underwent postCRT. Patients who received NCRT were more likely to be male (83% vs. 64%; p Z 0.013) and have a GEJ tumor (76% vs. 22%, p<0.001), greater number of involved lymph nodes (median 1 vs. 0; p Z 0.005), and higher clinical stage (p Z 0.002). Median RT dose was 50.4 Gy for neoadjuvant RT and 45.0 Gy for postoperative RT (p<0.001). Concurrent CTX was carboplatin/taxol (47%), cisplatin/fluorouracil (FU; 17%), or FOLFOX (folinic acid/FU/oxaliplatin; 14%) in the neoadjuvant setting and single-agent with FU (86%) in the postoperative setting (p<0.001). The NCRT group had a pathologic complete response (pCR) rate of 26% and had greater rate of R0 resection compared to the postCRT group (95% vs. 76%; p Z 0.002). NCRT vs. postCRT was associated with a lower rate of any Grade 3 or higher toxicity (10% vs. 54%; p<0.001). Only 1% had treatment break(s) in the NCRT setting vs. 10% in the postCRT setting (p Z 0.015). On multivariable analysis of OS, NCRT vs. postCRT (HR Z 0.57 [95% CI 0.36-0.91]; p Z 0.020) and R0 resection (HR Z 0.50 [95% CI 0.27-0.90]; p Z 0.021) were independently associated with lower hazards of death. The estimated 5-year OS was 67% (95% CI 0.55-0.76) in the NCRT group vs. 40% (95% CI 0.26-0.54) in the postCRT group (log-rank p Z 0.003). Conclusion: NCRT was associated with a higher rate of R0 resection and longer OS with a lower toxicity compared to postCRT. Our findings suggest NCRT is superior to postCRT and support randomized trials to establish the optimal timing of CRT in gastric cancer.
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