Changhoon Song

Elective pelvic versus prostate bed-only salvage radiotherapy following radical prostatectomy

PurposeTo compare the impact of elective whole pelvic radiotherapy (WPRT) versus prostate bed-only radiotherapy (PBRT) on biochemical relapse-free survival (bRFS) in prostate cancer patients treated with salvage radiotherapy following radical prostatectomy (RP).Patients and methodsIn our database, 163xa0lymph node-negative prostate cancer patients who had undergone salvage radiotherapy (SRT) for biochemical relapse after RP between Septemberxa02004 and Aprilxa02012 were identified. PBRT was administered to 134xa0patients (the PBRT group), while the remaining 29xa0patients (the WPRT group) received WPRT.ResultsMedian follow-up was 57xa0months (range 18–122xa0months). In the propensity score-matched cohort, the 4-year bRFS of the WPRT group was significantly higher compared to the PBRT group (63.1xa0vs. 43.4u2009%, pu2009=u20090.034). Subgroup analysis showed that the bRFS of patients who had two or more risk factors (seminal vesicle invasion, Roach score for lymph node invasionxa0≥u200945u2009%, and number of harvested lymph nodesxa0≤u20095) and were treated with WPRT was significantly improved compared to those who received PBRT (hazard ratio, HR 0.33; 95u2009% confidence interval, CIxa00.13–0.83; pu2009=u20090.018).ConclusionElective WPRT for SRT may improve bRFS in patients with unfavorable risk factors. These results need to be confirmed by a prospective randomized trial.ZusammenfassungZielVergleich der Auswirkungen der gezielten Beckenstrahlentherapie (WPRT) gegenüber der Prostatastrahlentherapie (PBRT) hinsichtlich des biochemischen rezidivfreien Überlebens (bRFS) bei Prostatakarzinompatienten, die nach radikaler Prostatektomie (RP) mit einer Salvage-Strahlentherapie (SRT) behandelt wurden.Patienten und MethodenAus unserer Datenbank wurden 163 lymphknotennegative Patienten mit Prostatakrebs identifiziert, die sich nach RP zwischen September 2004 und April 2012 wegen einem biochemischen Rückfall einer rettenden SRT unterzogen hatten. PBRT wurde 134xa0Patienten verabreicht (PBRT-Gruppe), während die übrigen 29xa0Patienten eine WPRT erhielten (WPRT-Gruppe).ErgebnisseDie mediane Nachbeobachtungszeit betrug 57xa0Monate (Spanne: 18–122xa0Monate). In der auf den Propensity-Score abgestimmten Kohorte war das 4-Jahres-bRFS der WPRT-Gruppe im Vergleich zur PBRT-Gruppe signifikant höher (63,1 vs. 43,4u2009%; pu2009=u20090,034). Eine Untergruppenanalyse zeigte, dass sich das bRFS der Patienten, die zwei oder mehr Risikofaktoren hatten (Samenblasenbefall, Roach-Score für Lymphknotenbefall ≥u200945u2009% und Zahl der entfernten Lymphknoten ≤u20095) und mit WPRT behandelt wurden, im Vergleich zu diejenigen, die PBRT erhalten hatten, deutlich verbessert (Hazard-Ratio 0,33; 95u2009%-Konfidenzintervall 0,13–0,83; pu2009=u20090,018).FazitEine gezielte WPRT-Strahlentherapie kann das bRFS bei Patienten mit ungünstigen Risikofaktorenverbessern. Diese Ergebnisse müssen in einer prospektiven randomisierten Studie bestätigt werden.

Elective pelvic versus prostate bed-only salvage radiotherapy following radical prostatectomy: A propensity score-matched analysis.

PurposeTo compare the impact of elective whole pelvic radiotherapy (WPRT) versus prostate bed-only radiotherapy (PBRT) on biochemical relapse-free survival (bRFS) in prostate cancer patients treated with salvage radiotherapy following radical prostatectomy (RP).Patients and methodsIn our database, 163xa0lymph node-negative prostate cancer patients who had undergone salvage radiotherapy (SRT) for biochemical relapse after RP between Septemberxa02004 and Aprilxa02012 were identified. PBRT was administered to 134xa0patients (the PBRT group), while the remaining 29xa0patients (the WPRT group) received WPRT.ResultsMedian follow-up was 57xa0months (range 18–122xa0months). In the propensity score-matched cohort, the 4-year bRFS of the WPRT group was significantly higher compared to the PBRT group (63.1xa0vs. 43.4u2009%, pu2009=u20090.034). Subgroup analysis showed that the bRFS of patients who had two or more risk factors (seminal vesicle invasion, Roach score for lymph node invasionxa0≥u200945u2009%, and number of harvested lymph nodesxa0≤u20095) and were treated with WPRT was significantly improved compared to those who received PBRT (hazard ratio, HR 0.33; 95u2009% confidence interval, CIxa00.13–0.83; pu2009=u20090.018).ConclusionElective WPRT for SRT may improve bRFS in patients with unfavorable risk factors. These results need to be confirmed by a prospective randomized trial.ZusammenfassungZielVergleich der Auswirkungen der gezielten Beckenstrahlentherapie (WPRT) gegenüber der Prostatastrahlentherapie (PBRT) hinsichtlich des biochemischen rezidivfreien Überlebens (bRFS) bei Prostatakarzinompatienten, die nach radikaler Prostatektomie (RP) mit einer Salvage-Strahlentherapie (SRT) behandelt wurden.Patienten und MethodenAus unserer Datenbank wurden 163 lymphknotennegative Patienten mit Prostatakrebs identifiziert, die sich nach RP zwischen September 2004 und April 2012 wegen einem biochemischen Rückfall einer rettenden SRT unterzogen hatten. PBRT wurde 134xa0Patienten verabreicht (PBRT-Gruppe), während die übrigen 29xa0Patienten eine WPRT erhielten (WPRT-Gruppe).ErgebnisseDie mediane Nachbeobachtungszeit betrug 57xa0Monate (Spanne: 18–122xa0Monate). In der auf den Propensity-Score abgestimmten Kohorte war das 4-Jahres-bRFS der WPRT-Gruppe im Vergleich zur PBRT-Gruppe signifikant höher (63,1 vs. 43,4u2009%; pu2009=u20090,034). Eine Untergruppenanalyse zeigte, dass sich das bRFS der Patienten, die zwei oder mehr Risikofaktoren hatten (Samenblasenbefall, Roach-Score für Lymphknotenbefall ≥u200945u2009% und Zahl der entfernten Lymphknoten ≤u20095) und mit WPRT behandelt wurden, im Vergleich zu diejenigen, die PBRT erhalten hatten, deutlich verbessert (Hazard-Ratio 0,33; 95u2009%-Konfidenzintervall 0,13–0,83; pu2009=u20090,018).FazitEine gezielte WPRT-Strahlentherapie kann das bRFS bei Patienten mit ungünstigen Risikofaktorenverbessern. Diese Ergebnisse müssen in einer prospektiven randomisierten Studie bestätigt werden.

Impact of Lymph Node Ratio on Oncologic Outcomes in ypStage III Rectal Cancer Patients Treated with Neoadjuvant Chemoradiotherapy followed by Total Mesorectal Excision, and Postoperative Adjuvant Chemotherapy

Purpose To evaluate the prognostic impact of the lymph node ratio (LNR) in ypStage III rectal cancer patients who were treated with neoadjuvant chemoradiotherapy (NCRT). Materials and Methods We retrospectively reviewed the data of 638 consecutive patients who underwent NCRT followed by total mesorectal excision, and postoperative adjuvant chemotherapy for rectal cancer from 2004 to 2011. Of these, 125 patients were positive for lymph node (LN) metastasis and were analyzed in this study. Results The median numbers of examined and metastatic LNs were 17 and 2, respectively, and the median LNR was 0.143 (range, 0.02–1). Median follow-up time was 55 months. In multivariate analyses, LNR was an independent prognostic factor for overall survival (OS) (hazard ratio [HR] 2.17, p = 0.041), disease-free survival (DFS) (HR 2.28, p = 0.005), and distant metastasis-free survival (DMFS) (HR 2.30, p = 0.010). When ypN1 patients were divided into low (low LNR ypN1 group) and high LNR (high LNR ypN1 group) according to a cut-off value of 0.152, the high LNR ypN1 group had poorer OS (p = 0.043) and DFS (p = 0.056) compared with the low LNR ypN1 group. And there were no differences between the high LNR ypN1 group and the ypN2 group in terms of the OS (p = 0.703) and DFS (p = 0.831). Conclusions For ypN-positive rectal cancer patients, the LNR was a more effective prognostic marker than the ypN stage, circumferential resection margin, or tumor regression grade after NCRT, and could be used to discern the high-risk group among ypN1 patients.

Improved survival with postoperative radiotherapy in thymic carcinoma: A propensity-matched analysis of Surveillance, Epidemiology, and End Results (SEER) database

OBJECTIVESnThymic carcinoma is a rare and aggressive malignancy with poor prognosis. Although postoperative radiotherapy (PORT) is used for obtaining better locoregional tumor control, its association with survival has not been established. This study evaluated the prognostic impact of PORT in thymic carcinoma.nnnMATERIALS AND METHODSnWe identified patients diagnosed with thymic carcinoma between 2004 and 2013 using the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching with Kaplan-Meier and Cox-regression analyses were used to assess prognosis.nnnRESULTSnIn the unmatched population (n=312), 184 (59%) patients underwent PORT. The 5-year overall survival rates were better with receipt of PORT, both before and after matching (P=0.012 and 0.007, respectively). After adjusting for related covariates (n=256), age ≥63 years (P=0.023), Masaoka stage III (P=0.028) and IV (P<0.001), debulking surgery (P=0.021), and no receipt of PORT (P=0.013) were independently poor prognostic factors. In subgroup analyses, favorable survival impacts of PORT were observed for Masaoka stage III tumors (hazard ratio [HR] 0.31, 95% confidence interval [CI] 0.15-0.66), tumors sized >6.0cm (HR 0.48, 95% CI 0.26-0.89), node-negative status (HR 0.58, 95% CI 0.33-1.00), and surgical extent of local excision or partial removal (HR 0.44, 95% CI 0.22-0.86).nnnCONCLUSIONnOn SEER analysis, survival benefits of PORT in thymic carcinoma were demonstrated. With strong prognostic associations of Masaoka stage and types of surgery, PORT should be considered for non-metastatic locally advanced tumors with limited surgical resection.

Comparison of Dosimetric Performance among Commercial Quality Assurance Systems for Verifying Pretreatment Plans of Stereotactic Body Radiotherapy Using Flattening-Filter-Free Beams

The purpose of this study was to compare the performance of different commercial quality assurance (QA) systems for the pretreatment verification plan of stereotactic body radiotherapy (SBRT) with volumetric arc therapy (VMAT) technique using a flattening-filter-free beam. The verification for 20 pretreatment cancer patients (seven lung, six spine, and seven prostate cancers) were tested using three QA systems (EBT3 film, I’mRT MatriXX array, and MapCHECK). All the SBRT-VMAT plans were optimized in the Eclipse (version 11.0.34) treatment planning system (TPS) using the Acuros XB dose calculation algorithm and were delivered to the Varian TrueBeam® accelerator equipped with a high-definition multileaf collimator. Gamma agreement evaluation was analyzed with the criteria of 2% dose difference and 2 mm distance to agreement (2%/2 mm) or 3%/3 mm. The highest passing rate (99.1% for 3%/3 mm) was observed on the MapCHECK system while the lowest passing rate was obtained on the film. The pretreatment verification results depend on the QA systems, treatment sites, and delivery beam energies. However, the delivery QA results for all QA systems based on the TPS calculation showed a good agreement of more than 90% for both the criteria. It is concluded that the three 2D QA systems have sufficient potential for pretreatment verification of the SBRT-VMAT plan.

Risk prediction model for disease-free survival in women with early-stage cervical cancers following postoperative (chemo)radiotherapy

Purpose: To investigate disease-free survival (DFS) and prognostic factors following the administration of postoperative (chemo)radiotherapy in patients with early-stage cervical cancers. Methods: The medical records of 1,069 patients from 10 participating institutions were reviewed. Statistically and clinically established factors were considered as candidates for constructing the prediction model. This model was validated, using bootstrapping to correct for optimistic bias. Results: The 5-year DFS rate was 81.1%, with a median follow-up period of 59.6 months. The statistically significant prognostic factors were as follows: pelvic lymph node metastasis, histologic type, parametrial invasion, lymphovascular space invasion, and tumor size. The nomogram for DFS was constructed, and it demonstrated a good discrimination performance, with an internally validated concordance index of 0.72. Conclusions: Our predictive model exhibited accurate predictions and may be useful in designing clinical trials to study if further chemotherapy can reduce the recurrence of disease in high-risk patients.

Emerging Role of Radiotherapy in Stage IV Prostate Cancer

Recently published retrospective studies using population based database showed prostate-directed radiation therapy could help stage IV prostate cancer patients with survival benefit compared with convention hormonal therapy alone. Also, small retrospective studies suggested metastasis-directed therapy using stereotactic radiation therapy (SBRT) in oligometastatic setting could provide excellent local control, progression free survival advantage and defer hormonal therapy timing resulting in the improvement of quality of life. These newly emerging roles of radiation therapy in stage IV prostate cancer are discussed in following sections.

Impact of Tumor Regression Grade as a Major Prognostic Factor in Locally Advanced Rectal Cancer after Neoadjuvant Chemoradiotherapy: A Proposal for a Modified Staging System

There is ongoing debate regarding the significance of complete or near-complete response after neoadjuvant chemoradiotherapy (CRT) for rectal cancer. This study assessed the prognostic value of the Dworak tumor regression grade (TRG) following neoadjuvant CRT and surgery primarily in patients with pathological stage (ypStage) II and III rectal cancer. The records of 331 patients who underwent neoadjuvant CRT followed by total mesorectal excision between 2004 and 2015 were retrospectively reviewed. Patients were categorized as having a good response (GR, TRG 3/4, n = 122) or a poor response (PR, TRG 1/2, n = 209). At a median follow-up of 65 months, five-year disease-free survival (DFS) was higher in the GR group than in the PR group (91.3% vs. 66.6%, p < 0.001). Patients with a GR and ypStage II disease had a five-year DFS that was indistinguishable from that of patients with ypStage 0–I disease (92.3% vs. 90.7%, p = 0.885). Likewise, patients with a GR and ypStage III disease had a five-year DFS similar to those with ypStage II disease (76.0% vs. 75.9%, p = 0.789). A new modified staging system that incorporates grouped TRG (GR vs. PR) was developed. The prognostic performance of this modified stage and the ypStage was compared with the Harrell C statistic. C statistic of the modified stage was higher than that of the ypStage (0.784 vs. 0.757, p = 0.012). The results remained robust after multivariate Cox regression analyses. In conclusion, a GR to neoadjuvant CRT is an independent predictor of good DFS and overall survival and further stratifies patients so as to estimate the risk of recurrence and survival among patients with ypStage II and III rectal cancer.

Optimal planning strategy among various arc arrangements for prostate stereotactic body radiotherapy with volumetric modulated arc therapy technique

Abstract Background The aim of this study was to determine the optimal strategy among various arc arrangements in prostate plans of stereotactic body radiotherapy with volumetric modulated arc therapy (SBRT-VMAT). Patients and methods To investigate how arc arrangements affect dosimetric and biological metrics, SBRT-VMAT plans for eighteen patients were generated with arrangements of single-full arc (1FA), single-partial arc (1PA), double-full arc (2FA), and double-partial arc (2PA). All plans were calculated by the Acuros XB calculation algorithm. Dosimetric and radiobiological metrics for target volumes and organs at risk (OARs) were evaluated from dosevolume histograms. Results All plans were highly conformal (CI<1.05, CN=0.91) and homogeneous (HI=0.09-0.12) for target volumes. For OARs, there was no difference in the bladder dose, while there was a significant difference in the rectum and both femoral head doses. Plans using 1PA and 2PA showed a strong reduction to the mean rectum dose compared to plans using 1FA and 2FA. Contrastively, the D2% and mean dose in both femoral heads were always lower in plans using 1FA and 2FA. The average tumor control probability and normal tissue complication probability were comparable in plans using all arc arrangements. Conclusions The use of 1PA had a more effective delivery time and produced equivalent target coverage with better rectal sparing, although all plans using four arc arrangements showed generally similar for dosimetric and biological metrics. However, the D2% and mean dose in femoral heads increased slightly and remained within the tolerance. Therefore, this study suggests that the use of 1PA is an attractive choice for delivering prostate SBRT-VMAT.

Epidemiology of Intracranial Metastases in Korea: A National Cohort Investigation

Purpose To investigate the epidemiologic features of intracranial metastases (ICMET) in Korea, we performed a cohort study using the National Health Insurance Service–National Sample Cohort database, which comprised healthcare usage information of approximately 1 million Korean individuals over 12 years. Materials and Methods We enrolled 998,602 subjects, after excluding 18,218 subjects diagnosed with any cancer during the washout period (2002-2004). The observation period was 9 years (2005-2013; 8,725,438 person-years). The initial diagnosis date of ICMET and the primary cancer was recorded. The incidence was determined based on the number of incident cases and observation size, whereas survival was estimated using death statistics from the database. Results Through observation period, a total 776 subjects developed ICMET. The age-standardized incidence of ICMET was 8.2 per 100,000 person-years. The mean interval between the initial diagnosis date of the primary cancer and ICMET was 13.1 months. Patients with ICMET had shorter survival than those without ICMET (30.9 months vs. 81.4 months, p < 0.001). The ICMET incidence among the cancer patients was 5.0 per 1,000 person-years; it was highest in lung cancer cases, followed by breast and liver cancer cases. Moreover, ICMET from lung cancer was the most common metastasis type, followed by ICMET from liver and breast cancer. Conclusion The incidence of ICMET was 8.2 per 100,000 person-years among the Korean population and 5.0 per 1,000 person-years among cancer patients. Most of the ICMET cases arose from lung cancer. ICMET also critically influenced survival in cancer patients.