Joo Hwan Lee

A comparison of dosimetric parameters between tomotherapy and three-dimensional conformal radiotherapy in rectal cancer

PurposeTomotherapy for intensity-modulated radiation has been demonstrated to reduce unnecessary irradiations to adjacent organs at risk (OARs). The purpose of this study was to compare the dosimetric parameters between Tomotherapy and three-dimensional conformal radiotherapy (3D-CRT) in rectal cancer patients.Materials and methodsWe redesigned three-dimensional conformal plans for 20 rectal cancer patients who had received short-course preoperative radiotherapy with Tomotherapy. The target coverage for 3D-CRT and Tomotherapy was evaluated with the following including the mean dose, VnGy, Dmin, Dmax, radiation conformality index (RCI), and radical dose homogeneity index (rDHI).ResultsThe mean PTV dose for Tomotherapy is significantly higher than that observed for the 3D-CRT (p = 0.043). However, there is no significant difference in the V23.25Gy, V26.25Gy, V27.5Gy, and RCI values between Tomotherapy and 3D-CRT. However, the average rDHI (p < 0.001) value for Tomotherapy was significantly lower than that reported for the 3D-CRT. Tomotherapy significantly lowered the mean level of irradiation doses to the bladder, small bowel, and femur heads as compared to 3D-CRT.ConclusionsTomotherapy could produce a favorable target coverage and significant dose reduction for the OARs at the expense of acceptable dose inhomogeneity of the PTV compared with 3D-CRT in rectal cancer patients.

The role of postoperative pelvic radiation in stage IV rectal cancer after resection of primary tumor.

Purpose To evaluate the effect of pelvic radiotherapy (RT) in patients with stage IV rectal cancer treated with resection of primary tumor with or without metastasectomy. Materials and Methods Medical records of 112 patients with stage IV rectal cancer treated with resection of primary tumor between 1990 and 2011 were retrospectively reviewed. Fifty-nine patients received synchronous or staged metastasectomy whereas fifty-three patients did not. Twenty-six patients received pelvic radiotherapy. Results Median overall survival (OS), locoregional recurrence-free survival (LRFS), and progression-free survival (PFS) of all patients was 27, 70, and 11 months, respectively. Pathologic T (pT), N (pN) classification and complete metastasectomy were statistically significant factors in OS (p = 0.040, 0.020, and 0.002, respectively). RT did not improve OS or LRFS. There were no significant factors in LRFS. pT and pN classification were also significant prognostic factors in PFS (p = 0.010 and p = 0.033, respectively). In the subgroup analysis, RT improved LRFS in patients with pT4 disease (p = 0.026). The locoregional failure rate of the RT group and the non-RT group were 23.1% and 33.7%, showing no difference in the failure pattern of both groups (p = 0.260). Conclusion Postoperative pelvic RT did not improve LRFS of all metastatic rectal cancer patients; however, it can be recommended to patients with pT4 disease. A complete resection of metastatic masses should be performed if possible.

High-Dose-Rate Brachytherapy for the Treatment of Vaginal Intraepithelial Neoplasia

Purpose Vaginal intraepithelial neoplasia (VAIN), a rare premalignant condition, is difficult to eradicate. We assess the effectiveness of high-dose rate intracavitary brachytherapy (HDR-ICR) in patients with VAIN or carcinoma in situ (CIS) of the vagina after hysterectomy. Materials and Methods We reviewed 34 patients treated for posthysterectomy VAIN or CIS of the vagina by brachytherapy as the sole treatment. All patients underwent a coloposcopic-directed punch biopsy or had abnormal cytology, at least 3 consecutive times. All patients were treated with a vaginal cylinder applicator. The total radiation dose was mainly 40 Gy in 8 fractions during the periods of 4 weeks at a prescription point of the median 0.2 cm (range, 0 to 0.5 cm) depth from the surface of the vaginal mucosa. Results Acute toxicity was minimal. Seven patients had grade 1/2 acute urinary and rectal complications. There were 15 cases of late toxicity, predominantly vaginal mucosal reaction in 12 patients. Of these patients, two patients suffered from grade 3 vaginal stricture and dyspareunia continuously. After a median follow-up time of 48 months (range, 4 to 122 months), there were 2 recurrences and 2 persistent diseases, in which a second-line therapy was needed. The success rate was 88.2%. The average prescription point in failure patients was 1.1 mm from the surface of the vagina compared to an average of 2.6 mm in non-recurrent patients (p=0.097). Conclusion HDR-ICR is an effective treatment method in VAIN patients. In spite of high cure rates, we should consider issues regarding vaginal toxicity and radiation techniques to reduce the occurrence of failure and toxicity.

Displacement of Surgical Clips during Postoperative Radiotherapy in Breast Cancer Patients Who Received Breast-Conserving Surgery.

Purpose Surgical clips are used as a target for postoperative breast radiotherapy, and displacement of surgical clips would result in inaccurate delivery of radiation. We investigated the displacement range of surgical clips in the breast during postoperative radiotherapy following breast-conserving surgery. Methods A total of 178 patients who received breast-conserving surgery and postoperative radiation of 59.4 Gy in 33 fractions to the involved breast for 6.5 weeks were included. Surgical clips were used to mark the lumpectomy cavity during breast-conserving surgery. Patients undertook planning computed tomography (CT) scan for whole breast irradiation. Five weeks after beginning radiation, when the irradiation dose was 45 Gy, planning CT scan was performed again for a boost radiotherapy plan in all patients. The surgical clips were defined in both CT images and compared in lateromedial (X), anteroposterior (Y), superoinferior (Z), and three-dimensional directions. Results The 90th percentile of displacement of surgical clips was 5.31 mm (range, 0.0–22.2 mm) in the lateromedial direction, 7.1 mm (range, 0.0–14.2 mm) in the anteroposterior direction, and 6.0 mm (range, 0.0–10.0 mm) in the superoinferior direction. The 90th percentile of three-dimensional displacement distance was 9.8 mm (range, 0.0–28.2 mm). On the multivariate analysis, seroma ≥15 mL was the only independent factor associated with the displacement of surgical clips. In patients with seroma ≥15 mL, the 90th percentile of displacement of surgical clips was 15.1 mm in the lateromedial direction, 12.7 mm in the anteroposterior direction, 10.0 mm in the superoinferior direction, and 21.8 mm in the three-dimensional distance. Conclusion A target volume expansion of 10 mm from surgical clips may be sufficient to compensate for the displacement of clips during postoperative radiotherapy after breast-conserving surgery. For patients who had a seroma, a replanning CT scan for a boost radiation should be considered to ensure exact postoperative radiotherapy in breast cancer.

Evaluation of tissue computed tomography number changes and dosimetric shifts after conventional whole-breast irradiation in patients undergoing breast-conserving surgery

The aim of this study was to assess tissue computed tomography (CT) number changes and corresponding dosimetric shifts in repeatedly performed simulation CT (re-sim CT) scans after conventionally fractionated irradiation in breast cancer patients. A total of 28 breast cancer patients who underwent breast-conserving surgery were enrolled in this study. All the patients had received 50.4 Gy of conventional whole-breast irradiation (WBI) and underwent re-sim CT scans for tumor bed boost. For evaluation of dosimetric shifts between initial and re-sim CT scans, electron boost plans in the same field size with the same monitor unit with source-to-skin distance of 100 cm were conducted. Dosimetric parameters (V105%, V103%, V100%, V98%, V95%, V90%: Vx% indicates volumes which receive X% of prescribed doses) between initial and re-sim CT scans were compared. The CT number data (CTmean, CTmax, CTmin) of the original and irradiated CT (re-sim CT) scans from each representative structure (lung, rib bone, soft tissue, muscle, etc.) were examined and recruited. CT numbers showed highly variable changes. Soft tissue CTmean and muscle CTmax/CTmin showed statistically and significantly increased values in the CT (re-sim CT) compared to the original CT scans. Rib bone CTmean/CTmin showed statistically and significantly decreased values in the re-sim CT compared to the original CT scans. Other CT number values showed no statistically significant changes. Among the dosimetric parameters, only V105% (p = 0.015, mean = 3.07 cc versus 1.63 cc) and V103% (p = 0.017, mean = 13.8 cc versus 11.9 cc) exhibited statistically increased values in the re-sim CT compared to the original CT scans. CT number changes after conventional WBI were different according to tissue component. For electron boost plans, the implementation of a re-sim CT might be helpfully considered because significant dosimetric factor changes were observed especially in the high-dose areas (hot spots: V105% and V103%).

Adjuvant and Salvage Radiation Therapy for Prostate Cancer After Radical Prostatectomy

Although radical prostatectomy (RP) provides excellent cancer control, tumor recurrence occurred in approximately 15–40% of patients within 5 years usually with elevated prostate-specific antigen (PSA) level [1, 2]. Postoperative radiation therapy is recommended for patients with adverse risk factors after complete surgical resection, subclinical disease detected by elevated postoperative serum PSA, or clinical tumor recurrence in prostatic fossa.

Treatment outcome of diffuse large B-cell lymphoma involving the head and neck: Two-institutional study for the significance of radiotherapy after R-CHOP chemotherapy

Abstract This study was performed to analyze the treatment outcome for diffuse large B-cell lymphoma (DLBCL) involving the head and neck and to evaluate the role of radiotherapy in the rituximab era. Fifty-six patients diagnosed with DLBCL involving the head and neck were assessed. All patients were treated with 6 cycles of rituximab, cyclophosphamide, adriamycin, vincristine, and prednisolone (R-CHOP). After chemotherapy, radiation was delivered to the head and neck area in a median dose of 36 Gy. Radiation was delivered using 3-dimensional radiotherapy (n  =  25) or intensity-modulated radiotherapy (n  =  31). Primary endpoints were relapse-free survival (RFS), overall survival (OS), and local control rate. After median follow-up time of 45 months, the 5-year RFS and OS rates were 72% and 61%, respectively. Fourteen (25%) of 56 patients relapsed; 1 had a local relapse, 11 had distant relapses, and 2 had both local and distant relapses. The final local control rate after radiotherapy was 94%. Age, performance status, international prognostic index score, and radiotherapy response were significant prognostic factors for both RFS and OS in the multivariate analysis. Incidence of acute grade 3 and 4 hematologic toxicity was 9% and 4%, respectively. Grade 3 nonhematologic toxicity occurred in 2 (4%) patients, and there was no grade 4 nonhematologic toxicity for the irradiated patients. Excellent local control and survival rates can be achieved with R-CHOP followed by radiotherapy in patients with DLBCL involving the head and neck. Treatment-related toxicity after the introduction of modern radiotherapy was acceptable and limited.