Hypofractionated Radiotherapy for Early-Stage Breast Cancer: A Propensity Score Matched Analysis

Background@#In patients with early-stage breast cancer, the treatment results of hypofractionated radiation therapy (RT) and conventional RT are evaluated in efficacy and cost. @*Methods@#We retrospectively evaluated 280 patients with early-stage (Tis-2N0M0) breast cancer (including 100 hypofractionated RT patients) with regards to treatment outcomes according to the RT schedule. The median whole-breast RT dose was 42.56 Gy/16 fractions for hypofractionated RT and 50.4 Gy/28 fractions for conventional RT. Most patients (n = 260, 92.9%) additionally received a tumor bed boost RT. We used propensity score matching (PSM) analysis to balance the baseline risk factors for recurrence. The co-primary endpoints of this study were disease-free survival (DFS) and ipsilateral breast tumor recurrence (IBTR).DFS or IBTR was analyzed using the Kaplan-Meier survival curve and log-rank test. @*Results@#Total 89 pairs of matched patients (1:1 matching, n = 178) were finally evaluated.The median follow-up was 23.6 months. After matching, the 3-year DFS was 100% in the hypofractionated RT group and 98.4% in the conventional RT group; there was no significant difference in DFS between the groups (P = 0.374). Furthermore, the IBTR did not differ between the hypofractionated RT and conventional RT groups (P = 0.374) after matching. The 3-year overall survival was not different between two groups (both 100%). Hypofractionated RT saved 26.6% of the total cost of RT compared to conventional RT. Additionally, the acute skin toxicity rate (≥ grade 2) was also not significantly different between the groups (hypofractionated RT: 10.1% vs. conventional RT: 2.2%). @*Conclusion@#Hypofractionated RT showed good IBTR and DFS, which were compatible to those in conventional RT in breast cancer. Hypofractionated RT is expected to be used more widely because of its low cost and convenience.

Maximum standardized uptake value at pre-treatment PET in estimating lung cancer progression after stereotactic body radiotherapy

PURPOSE: This study aimed to identify the feasibility of the maximum standardized uptake value (SUVmax) on baseline 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) as a predictive factor for prognosis in early stage primary lung cancer treated with stereotactic body radiotherapy (SBRT). MATERIALS AND METHODS: Twenty-seven T1-3N0M0 primary lung cancer patients treated with curative SBRT between 2010 and 2018 were retrospectively evaluated. Four patients (14.8%) treated with SBRT to address residual tumor after wedge resection and one patient (3.7%) with local recurrence after resection were included. The SUVmax at baseline PET/CT was assessed to determine its relationship with prognosis after SBRT. Patients were divided into two groups based on maximum SUVmax on pre-treatment FDG PET/CT, estimated by receiver operating characteristic curve. RESULTS: The median follow-up period was 17.7 months (range, 2.3 to 60.0 months). The actuarial 2-year local control, progressionfree survival (PFS), and overall survival were 80.4%, 66.0%, and 78.2%, respectively. With regard to failure patterns, 5 patients exhibited local failure (in-field failure, 18.5%), 1 (3.7%) experienced regional nodal relapse, and other 2 (7.4%) developed distant failure. SUVmax was significantly correlated with progression (p = 0.08, optimal cut-off point SUVmax > 5.1). PFS was significantly influenced by pretreatment SUVmax (SUVmax > 5.1 vs. SUVmax ≤ 5.1; p = 0.012) and T stage (T1 vs. T2-3; p = 0.012). CONCLUSION: SUVmax at pre-treatment FDG PET/CT demonstrated a predictive value for PFS after SBRT for lung cancer.

Adverse effect of excess body weight on survival in cervical cancer patients after surgery and radiotherapy

PURPOSE: This study aimed to assess the effects of body mass index (BMI) on survival in cervical cancer patients who had undergone surgery and radiotherapy (RT). MATERIALS AND METHODS: We retrospectively reviewed the medical records of 70 cervical cancer patients who underwent surgery and RT from 2007 to 2012. Among them, 40 patients (57.1%) had pelvic lymph node metastases at the time of diagnosis. Sixty-seven patients (95.7%) had received chemotherapy. All patients had undergone surgery and postoperative RT. Median BMI of patients was 22.8 kg/m² (range, 17.7 to 35.9 kg/m²). RESULTS: The median duration of follow-up was 52.3 months (range, 16 to 107 months). Twenty-four patients (34.3%) showed recurrence. Local failure, regional lymph nodal failure, and distant failure occurred in 4 (5.7%), 6 (8.6%), and 17 (24.3%) patients, respectively. The 5-year actuarial pelvic control rate was 83.4%. The 5-year cancer-specific survival (CSS) and disease-free survival (DFS) rates were 85.1% and 65.0%, respectively. The presence of pelvic lymph node metastases (n = 30) and being overweight or obese (n = 34, BMI ≥ 23 kg/m²) were poor prognostic factors for CSS (p = 0.003 and p = 0.045, respectively). Of these, pelvic lymph node metastasis was an independent prognostic factor (p = 0.030) for CSS. CONCLUSION: Overweight or obese cervical cancer patients showed poorer survival outcomes than normal weight or underweight patients. Weight control seems to be important in cervical cancer patients to improve clinical outcomes.

Correction: Adverse effect of excess body weight on survival in cervical cancer patients after surgery and radiotherapy

The authors noticed that the original version of this paper contains typographical error in Fig. 2.

Eribulin Mesylate Combined with Local Treatment for Brain Metastasis from Breast Cancer: Two Case Reports / 한국유방암학회지

The prognosis associated with brain metastasis arising from breast cancer is very poor. Eribulin is a microtubule dynamic inhibitor synthesized from halichondrin B, a natural marine product. In a phase III study (EMBRACE), eribulin improved overall survival in patients with heavily pretreated metastatic breast cancers. However, these studies included few patients with brain metastases. Metastatic brain tumors (MBT) were detected during first-line palliative chemotherapy in a 43-year-old woman with breast cancer metastasis to the lung and mediastinal nodes; the genetic subtype was luminal B-like human epidermal growth factor receptor 2 (HER2)-negative. Whole brain radiotherapy (WBRT) followed by eribulin treatment continuously decreased the size, and induced regression, of the MBT with systemic disease stability for 12 months. Another 48-year-old woman with metastatic breast cancer (HER2+ subtype) presented with MBT. Following surgical resection of the tumor, eribulin with concurrent WBRT showed regression of the MBT without systemic progression for 18 months.

Efficacy of Dose-Escalated Radiotherapy for Recurrent Colorectal Cancer

PURPOSE: This study aimed to evaluate the effects of radiotherapy (RT) on progression-free survival (PFS) for patients with recurrent colorectal cancer. METHODS: We reviewed the records of 22 patients with recurrent colorectal cancer treated with RT between 2008 and 2014. The median radiation dose for recurrent disease was 57.6 Gy (range, 45-75.6 Gy). Patients were divided into 2 groups according to the type of RT: patients underwent RT without previous history of irradiation (n = 14) and those treated with secondary RT (reirradiation: n = 8) at the time of recurrence. RESULTS: The median follow-up period was 24.9 months (range, 4.5-66.6 months). Progression was observed in 14 patients (including 8 with loco-regional failure and 9 with distant metastases). Distant metastases were related to the RT dose (<70 Gy, P = 0.031). The 2-year loco-regional control (LRC), PFS, and overall survival (OS) rates were 74.6%, 45.1%, and 82.0%, respectively. The LRC rate was not different between the patients treated with RT for the first time and those treated with reirradiation (P = 0.101, 2-year LRC 79.5% vs. 41.7%). However, reirradiation was related to poor PFS (P = 0.022) and OS (P = 0.002). An escalated RT dose (≥70 Gy) was associated with a higher PFS (P = 0.014, 2-year PFS 63.5% vs. 20.8%). CONCLUSION: Salvage RT for locally recurrent colorectal cancer can be offered when surgery is impossible. Dose-escalated RT shows a possible benefit in reducing the risk of progression.

Being Overweight or Obese Increases the Risk of Progression in Triple-Negative Breast Cancer after Surgical Resection

This study aimed to evaluate the association between body mass index (BMI) and progression in triple-negative breast cancer (TNBC). We retrospectively reviewed the medical records of 50 patients with TNBC who underwent breast-conserving surgery or mastectomy between 2007 and 2014. All patients were classified according to BMI (median 23.5 kg/m2, range 17.2-31.6 kg/m2): 31 patients (62%) were classified as being overweight or obese (BMI ≥ 23 kg/m2) and 19 patients (38%) were classified as having a normal body weight (BMI < 23 kg/m2). The median follow-up for patients was 31.1 months (range, 6.7-101.9 months). Progression occurred in 7 patients (14%), including 5 ipsilateral breast tumor recurrences, 2 regional lymph node metastases, and 5 distant metastases. Progression was significantly correlated with overweight or obese patients (P = 0.035), while none of the normal weight patients showed progression. The 3-year disease-free survival (DFS) and overall survival (OS) rates were 85.0% and 87.7%, respectively. DFS was significantly reduced in overweight or obese patients compared to that in normal weight patients (P = 0.035). However, OS was not significantly compromised by being overweight or obese (P = 0.134). In conclusion, being overweight or obese negatively affects DFS in TNBC patients.

Association between obesity and local control of advanced rectal cancer after combined surgery and radiotherapy

PURPOSE: The association between metabolism and cancer has been recently emphasized. This study aimed to find the prognostic significance of obesity in advanced stage rectal cancer patients treated with surgery and radiotherapy (RT). MATERIALS AND METHODS: We retrospectively reviewed the medical records of 111 patients who were treated with combined surgery and RT for clinical stage 2-3 (T3 or N+) rectal cancer between 2008 and 2014. The prognostic significance of obesity (body mass index [BMI] ≥25 kg/m²) in local control was evaluated. RESULTS: The median follow-up was 31.2 months (range, 4.1 to 85.7 months). Twenty-five patients (22.5%) were classified as obese. Treatment failure occurred in 33 patients (29.7%), including local failures in 13 patients (11.7%), regional lymph node failures in 5, and distant metastases in 24. The 3-year local control, recurrence-free survival, and overall survival rates were 88.7%, 73.6%, and 87.7%, respectively. Obesity (n = 25) significantly reduced the local control rate (p = 0.045; 3-year local control, 76.2%), especially in women (n = 37, p = 0.021). Segregation of local control was best achieved by BMI of 25.6 kg/m² as a cutoff value. CONCLUSION: Obese rectal cancer patients showed poor local control after combined surgery and RT. More effective local treatment strategies for obese patients are warranted.

The Effect of Probiotics for Preventing Radiation-Induced Morphological Changes in Intestinal Mucosa of Rats

Radiation therapy is an important treatment modality for abdominal or pelvic cancer, but there is a common and serious complication such as radiation-induced enteritis. Probiotics is reported to have positive effects against radiation-induced enteropathy. In this study, morphological changes of bowel mucosa were analyzed in rats to presume the effect of probiotics on radiation-induced enteritis and its correlation with radiation dose. A total of 48 adult male Sprague-Dawley rats were randomly assigned to two groups and received a solution containing 1.0x108 colony-forming units of Lactiobacillus acidophilus or water once daily for 10 days. Each of two groups was divided into three subgroups and abdomino-pelvic area of each subgroup was irradiated with 10, 15, and 20 Gy, respectively on the seventh day of feeding the solutions. All rats were sacrificed 3 days after irradiation and the mucosal thickness and villus height of jejunum, ileum and colon were measured. The morphological parameters of the small intestine represented significant differences between two solution groups irradiated 10 or 15 Gy, except for villus height of jejunum in 15 Gy-subgroup (P=0.065). There was no significant morphometric difference between two groups irradiated with 20 Gy of radiation. Probiotics appear to be effective for the morphological shortening of small intestinal mucosa damaged by radiation less than or equal to 15 Gy.

Analysis of Biologically Equivalent Dose of Stereotactic Body Radiotherapy for Primary and Metastatic Lung Tumors / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The purpose of this study was to determine the optimal biologically equivalent dose (BED) for stereotactic body radiotherapy (SBRT) by comparing local control rates in proportion to various total doses and fractionation schedules. MATERIALS AND METHODS: Thirty-four patients with early non-small-cell lung cancer and a single metastatic lung tumor were included in this study. Differences in local control rates were evaluated according to gender, primary tumor site, response, tumor size, and BED. For comparison of BEDs, the prescribed dose for SBRT was stratified according to three groups: high (BED > 146 Gy), medium to high (BED, 106 to 146 Gy), and low to medium (BED or = 3 cm showed a significant dose-response relationship. The observed 2-year local recurrence-free survival rates in patients with a tumor size of or = 3 cm were 96.2% and 50.0%, respectively, which were significantly different (p=0.007). CONCLUSION: BED > 100 Gy is required in order to achieve a > 85% local control rate regardless of tumor size. The optimal dose for small tumors of 150 Gy) may be required for patients with a tumor size larger than 3 cm.

The Suitability of Absorbable Mesh Insertion for Oncoplastic Breast Surgery in Patients with Breast Cancer Scheduled to Be Irradiated / 한국유방암학회지

PURPOSE: The objective of this study was to investigate the influence of radiotherapy on the cosmetic outcome after immediate breast reconstruction using an absorbable mesh in breast cancer. METHODS: From July 2008 to July 2009, 35 breast cancer patients who received immediate breast reconstruction with absorbable mesh insertion at the time of breast conserving surgery followed by radiotherapy were retrospectively studied. RESULTS: In 91% of cases there was an excellent or good cosmetic outcome before the initiation of radiotherapy, and in 8.6% the outcome was fair at this point. However, 6 months after surgery and irradiation, the rate of excellent to good cosmetic outcomes had decreased to 60% and fair outcomes had increased to 25.7%. Contrary to the decreased rate of good cosmetic outcomes from 65.7% to 42.9% at 1 year after operation, the rate of fair to poor outcomes considerably increased from 8.6% to 57.1%. The significant factors affecting cosmetic outcomes were pathology, specimen volume, and the estimated percentage of breast volume excised (EPBVE). Chemotherapy affected the cosmetic outcome at borderline significance level. Age, breast volume tumor site, insertion of drain, radiation dose, and time elapsed between surgery and radiotherapy were not significantly associated with the cosmetic outcome. CONCLUSION: Applying an absorbable mesh for the immediate reconstruction of the breast should be carefully considered in patients with an EPBVE of over 30% who are scheduled to be irradiated.

Volumetric changes in the lumpectomy cavity during whole breast irradiation after breast conserving surgery

PURPOSE: This study was performed to evaluate the change in the lumpectomy cavity volumes before and after whole breast radiation therapy (WBRT) and to identify factors associated with the change of volume. MATERIALS AND METHODS: From September 2009 to April 2010, the computed tomography (CT) simulation data from 70 patients obtained before and after WBRT was evaluated. The lumpectomy cavity volumes were contoured based on surgical clips, seroma, and postoperative changes. Significant differences in the data from pre-WBRT CT and post-WBRT CT were assessed. Multiple variables were examined for correlation with volume reduction in the lumpectomy cavity. RESULTS: The mean and median volume reduction in the lumpectomy cavity after WBRT were 17.6 cm3 and 16.1 cm3, respectively with the statistical significance (p < 0.001). The volume reduction in the lumpectomy cavity was inversely correlated with time from surgery to radiation therapy (R = 0.390). The presence of seroma was significantly associated with a volumetric change in the lumpectomy cavity after WBRT (p = 0.011). CONCLUSION: The volume of lumpectomy cavity reduced significantly after WBRT. As the time from surgery to the start of WBRT increased, the volume reduction in the lumpectomy cavity during WBRT decreased. A strong correlation was observed between the presence of seroma and the reduced volume. To ensure appropriate coverage and to limit normal tissue exposure during boost irradiation in patients who has seroma at the time of starting WBRT, repeating CT simulation at boost planning is suggested.

Comparison of Stereotactic Radiosurgery and Whole Brain Radiotherapy in Patients with Four or More Brain Metastases / 대한방사선종양학회지

PURPOSE: This study was a retrospective evaluation of the efficacy of stereotactic radiosurgery (SRS) in patients with >4 metastases to the brain. MATERIALS AND METHODS: Between January 2004 and December 2006, 68 patients with > or = 4 multiple brain metastases were included and reviewed retrospectively. Twenty-nine patients received SRS and 39 patients received whole brain radiotherapy (WBRT). Patients with small cell lung cancers and melanomas were excluded. The primary lesions were non-small cell lung cancer (69.0%) and breast cancer (13.8%) in the SRS group and non-small cell lung cancer (64.1%), breast cancer (15.4%), colorectal cancer (12.8%), esophageal cancer (5.1%) in the WBRT group. SRS involved gamma-knife radiosurgery and delivered 10~20 Gy (median, 16 Gy) in a single fraction with a 50% marginal dose. WBRT was delivered daily in 3 Gy fractions, for a total of 30 Gy. After completion of treatment, a follow-up brain MRI or a contrast-enhanced brain CT was reviewed. The overall survival and intracranial progression-free survival were compared in each group. RESULTS: The median follow-up period was 5 months (range, 2~19 months) in the SRS group and 6 months (range, 4~23 months) in the WBRT group. The mean number of metastatic lesions in the SRS and WBRT groups was 6 and 5, respectively. The intracranial progression-free survival and overall survival in the SRS group was 5.1 and 5.6 months, respectively, in comparison to 6.1 and 7.2 months, respectively, in the WBRT group. CONCLUSION: SRS was less effective than WBRT in the treatment of patients with >4 metastases to the brain.

Clinical Outcome after Breast Conserving Surgery and Radiation Therapy for Early Breast Cancer / 대한방사선종양학회지

PURPOSE: This study was performed to evaluate the disease-free survival and risk factors of recurrence in early breast cancer patients who have undergone breast conserving surgery and radiation therapy. MATERIALS AND METHODS: From March 1997 to December 2002, 77 breast cancer patients who underwent breast conserving surgery and radiation therapy were reviewed retrospectively. The median follow-up time was 58.4 months (range 43.8~129.4 months) and the mean subject age was 41 years. The frequency distribution of the different T stages, based on the tumor characteristics was 38 (49.3%) for T1, 28 (36.3%) for T2, 3 for T3, 7 for Tis and 1 for an unidentified sized tumor. In addition, 52 patients (67.5%) did not have axillary lymph metastasis, whereas 14 patients (18.1%) had 1~3 lymph node metastases and 3 (0.03%) had more than 4 lymph node metastases. The resection margin was negative in 59 patients, close (< or =2 mm) in 15, and positive in 4. All patients received radiation therapy at the intact breast using tangential fields with a subsequent electron beam boost to the tumor bed at a total dose ranging from 59.4 Gy to 66.4 Gy. Patients with more than four positive axillary lymph nodes received radiation therapy (41.4~60.4 Gy) at the axillary and supraclavicular area. Chemotherapy was administered in 59 patients and tamoxifen or fareston was administered in 29 patients. RESULTS: The 5 year overall survival and disease-free survival rates were 98.08% and 93.49%, respectively. Of the 77 patients, a total of 4 relapses (5.2%), including 1 isolated supraclavicular relapse, 1 supraclavicular relapse with synchronous multiple distant relapses, and 2 distant relapses were observed. No cases of local breast relapses were observed. Lymph node metastasis or number of metastatic lymph nodes was not found to be statistically related with a relapse (p=0.3289) nor disease-free survival (p=0.1430). Patients with positive margins had a significantly shorter disease-free survival period (p<0.0001) and higher relapse rates (p=0.0507). However, patients with close margins were at equal risk of relapse and disease-free survival as with negative margins (p=1.000). Patients younger than 40 years of age had higher relapse rates (9.3% vs. 0%) and lower disease-free survival periods, but the difference was not statistically significant (p=0.1255). The relapse rates for patients with tumors was 14% for tumor stage T2, compared to 0% for tumor stage T1 tumors (p=0.0284). A univariate analysis found that disease-free survival and relapse rates, T stage, positive resection margin and mutation of p53 were significant factors for clinical outcome. CONCLUSION: The results of this study have shown that breast conservation surgery and radiation therapy in early breast cancer patients has proven to be a safe treatment modality with a low relapse rate and high disease-free survival rate. The patients with a positive margin, T2 stage, and mutation of p53 are associated with statistically higher relapse rates and lower disease-free survival.

The Protective Effects of Vitamin C on Hepatotoxicity Induced by Radiation / 대한방사선종양학회지

PURPOSE: This study was carried out to determine the protective effects of vitamin C on the hepatotoxicity induced by radiation. MATERIALS AND METHODS: The Spraque Dawley rats were randomly divided into 3 groups; the control group, the radiation exposed group, and the radiation and vitamin C-treated group. SOD activity, catalase, malondialdehyde and liver enzymes were analyzed to assess the antioxidant effects of vitamin C. RESULTS: The increased level of malondialdehyde and the decreased catalase activity that were induced by radiation were improved after vitamin C but there was no statistical significance among three groups. The superoxide dismutase activity of the liver was increased by vitamin C, but there were no statistically significant differences between the vitamin C-treated group and the non vitamin C-treated group. The level of liver enzymes in sera such as glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactate dehyrogenase and alkaline phosphatase were remarkably elevated by radiation. The levels of those enzymes were decreased in the vitamin C-treated group and statistical significance was noted for the GPT level (p<0.01). On the lectromicrographic findings, the hepatic cell destruction was considerably decreased in the vitamin C-treated group. CONCLUSION: Vitamin C is thought to be an effective antioxidant against the hepatotoxicity induced by radiation.

Treatment Outcome of Postoperative Radiotherapy in Extrahepatic Bile Duct Cancer / 대한방사선종양학회지

PURPOSE: To evaluate the efficacy of radiotherapy, and the factors affecting survival in patients of extrahepatic bile duct cancer, by analyzing the results of postoperative radiotherapy. MATERIALS AND METHODS: Between October 1991 and July 2001, 21 patients with extrahepatic bile duct cancer, who received radiotherapy after a radical resection, were retrospectively reviewed. The patients' ages ranged from 39 to 75 years, with a median of 61 years, and a male to female ratio of 16 to 5. The numbers of patients with proximal and distal bile duct cancer were 14 and 7, respectively. From the postoperative pathological examination, 19 of the patients were found to have microscopic residues, and 7 to be lymph node positive. Patients with AJCC stages I, II and III were 10, 10 and 1, respectively. The total radiation dose administered was 4,500~6,300 cGy, with a median dose of 5,040 cGy. The follow up period was 20~81 months, with a median of 57.5 months. RESULTS: The overall and disease free survival rates at 3 and 5 years were 41.0 and 29.3%, and 41.6 and 29.7%, respectively. The influences of age, sex, tumor location, differentiation, microscopic residue, neural invasion, T and N stage, the stage itself, the dose of radiation and chemotherapy, on survival were evaluated. The T stage and the stage itself were found to be significant from a univariate analysis (p< 0.05), but the degree of significance was limited by the small number of patients. A recurrence occurred in 12 patients (57.1%), 5 in locoregional sites, 4 in distant sites and 3 in a combination of locoregional and distant sites, and the sites of distant metastasis were the liver, 6, and the bone, 1. Grade 2 or 3 acute leucopenias occurred in 2 patients and grade 2 chronic peptic ulcers occurred in 4, who were all recovered by conservative management. CONCLUSION: Postoperative radiotherapy is feasible in extrahepatic bile duct cancer, with tolerable toxicity, but prospective studies, with a large patient enrollment, are needed for the evaluation of the effects of postoperative radiotherapy and the related prognostic factors.

Optimal Radiation Therapy Field for Malignant Astrocytoma and Glioblastoma Multiforme / 대한방사선종양학회지

PURPOSE: This study was performed to determine the optimal radiation therapy field for the treatment of malignant astrocytoma and glioblastoma multiforme. MATERIALS AND METHODS: From Jan. 1994 to Mar. 2000, 21 patients with malignant astrocytoma and glioblastoma multiforme, confirmed as recurrent by follow up MRI after surgery and radiation therapy, were analyzed. The distance from the margin of the primary lesion to the recurrent lesion was measured. The following factors were analyzed to investigate the influence of these factors to recurrence pattern; tumor size, degree of edema, surgical extent, gamma knife radiosurgery and multiple lesions. RESULTS: Among the 21 patients, 18 (86%) were recurred within 2 cm from the primary lesion site. 12 within 1 cm, 6 between 1 and 2 cm. The other 3 patients all with multiple lesions, were recurred at 3, 4, 5 cm, from the primary lesion site. The recurrence pattern was not influenced by the factors of tumor size, extent of edema, surgical extent, or gamma knife radiosurgery. However, patients with multiple lesions showed a tendency of recurrence at sites further from the primary lesion. CONCLUSIONS: Most (86%) of the recurrences of malignant astrocytoma and glioblastoma multiforme occurred within 2 cm from the primary lesion site. The width of treatment field does not need to be changed according to tumor size, degree of edema, surgical extent, or gamma knife radiosurgery. However, the treatment field for multiple lesions appears to be wider than that for a single lesion.