Pre-operative versus post-operative radiosurgery for brain metastasis: Effects on treatment volume and inter-observer variability.

PURPOSE/OBJECTIVES: Compared to post-operative whole brain radiotherapy, resection cavity radiosurgery reduces impact on neuro-cognitive function and improves quality-of-life. However, coverage of the operative tract, in addition to tumour bed, may lead to large treatment volumes and inter-observer variability. We hypothesized that pre-operative radiosurgery reduces target volume size and inter-observer variability compared to post-operative radiosurgery. MATERIALS/METHODS: We identified 10 consecutive patients, with solitary brain metastasis, treated with post-operative cavity radiosurgery.Pre- and post-operative axial T1 contrast MRI were co-registered with the planning CT scans. Three radiation oncologists independently contoured the target volumes on the pre- and post-operative imaging. A 2mm-PTV margin was utilized for both strategies and radiosurgery treatment plans were generated. The following parameters were evaluated in the 2 plans: Mean target volume (cc), 50% isodose volume (cc), Inter-observer variability (Jaccard Index JI) and Conformity Index (CI). RESULTS: There was no significant difference in the mean target volume, nor 50% isodose volume, between pre- and post-operative strategies. (17.6 (95% CI 9.98 - 25.22) versus 19.4 (95% CI 10.11 - 28.69) cc, P=0.80; 61.7 (95% CI 38.4 - 85.0) vs 77.7 (95% CI 34.94 - 120.46) cc, P=0.65). There was significantly less inter-observer variability and improved conformity in the pre-operative group (Mean JI 0.84(95% CI 0.82 - 0.86) versus 0.70 (95% CI 0.62 - 0.78), P = 0.005; Mean CI 1.32 (95% CI 1.26 - 1.38) vs 1.45 (95% CI 1.36 - 1.54), P= 0.01). Planned subgroup analysis did not reveal any significant difference (between pre- vs post-op) in the mean volume of cystic versus non-cystic metastasis. Deep lesions (>2.5cm from dura) had a larger post-operative target volume (25.8 (95% CI 15.1 - 36.5) vs 12.3 (95% CI 6.54 - 18.06) cc, P=0.06) compared to superficial lesions. CONCLUSION: Pre-operative radiosurgery has less inter-observer variability and improved plan conformity. However, there was no difference in mean target volume between the pre- versus post-operative radiation. Contouring guidelines, and peer review, may help to reduce inter-observer variability for cavity radiosurgery.

Sci-Thur AM: Planning - 10: Improved dosimetric accuracy for patient specific quality assurance using a dual-detector measurement method for cyberknife output factors.

The measurement of output factors for small fields is challenging and can lead to large dose errors in patient treatments if corrections for detector size and scatter from high-Z material are not applied. Due to its high spatial resolution and near tissue equivalence, GAFCHROMIC® film potentially provides a correction free measure of output factors but it can be challenging to obtain high quality dosimetric results using this film. We propose minimizing errors in the clinical determination of small field output factors by employing diode measurements with Monte-Carlo generated corrections for small fields ≤10 mm diameter and using small volume ion chambers for apertures >10 mm diameter with independent validation using radiochromic film. We performed patient specific quality assurance (QA) measurements for 9 patients using GAFCHROMIC® film and an A16 small volume ion chamber in a head-shaped phantom, employing this hybrid dual detector method for relative output factor measurements within the Multiplan treatment planning system. Our results suggest that consistent output factors can be determined using this method with experimental verification using GAFCHROMIC® film dosimetry. For the patient specific QA using film, we achieve good dosimetric agreement (<2σ) of the measured and calculated average dose for pixels within the 80% isodose line. For patient specific QA using the micro-ion chamber, we get good agreement (<3%) for cone sizes greater than 5 mm. The differences observed for the 5 mm cone plans are consistent with a 1 mm radial setup uncertainty for patient positioning using the Cyberknife system.

Irinotecan in combination with 5-fluorouracil and folinic acid or with cisplatin in patients with advanced gastric or esophageal-gastric junction adenocarcinoma: results of a randomized phase II study.

BACKGROUND: To identify the most effective of two combinations, irinotecan/5-fluorouracil (5-FU)/folinic acid (FA) and irinotecan/cisplatin, in the treatment of advanced gastric cancer, for investigation in a phase III trial. PATIENTS AND METHODS: Patients were randomized to receive irinotecan [80 mg/m2 intravenously (i.v.)], FA (500 mg/m2 i.v.) and a 22-h infusion of 5-FU (2000 mg/m2 i.v.), weekly for 6 weeks with a 1-week rest, or irinotecan (200 mg/m2 i.v.) and cisplatin (60 mg/m2 i.v.), on day 1 for 3 weeks. RESULTS: A total of 115 patients were eligible for analysis in the per-protocol population. The overall response rate in the irinotecan/5-FU/FA arm (n=59) was 42.4%, with a complete response rate of 5.1%. Corresponding figures for the irinotecan/cisplatin arm (n=56) were 32.1% and 1.8%, respectively. The median time to progression was 6.5 months (irinotecan/5-FU/FA) and 4.2 months (irinotecan/cisplatin) (P < 0.0001), with median survival times of 10.7 and 6.9 months, respectively (P=0.0018). The major toxicity was grade 3/4 neutropenia, which was more pronounced with irinotecan/cisplatin than with irinotecan/5-FU/FA (65.7% versus 27%). Diarrhea was the main grade 3/4 non-hematological toxicity with both irinotecan/5-FU/FA (27.0%) and irinotecan/cisplatin (18.1%). CONCLUSIONS: Both combinations were active, with acceptable safety profiles. Irinotecan/5-FU/FA was selected as the most effective combination for investigation in a phase III trial in advanced gastric cancer.

Secretory breast cancer in a 7.5-year old boy.

Breast cancer is extremely rare in children, and consequently no consensus has been reached on the optimal treatment modalities. The medical history and treatment plan for a 7.5-year old male breast cancer patient is described. Radical mastectomy with sentinel node biopsy was performed in October 2002. As no malignant cells were detected in the sentinel node, and no BRCA1-2 mutations were detected, no further radio- or chemotherapy was performed. A "wait-and-see" policy was decided on. Further treatment will be given if this becomes necessary with the development of metastases.

[Radiation sensitivity testing and late neurological complications following radiosurgery for AVM: the use of SF2 from fibroblasts as a predictive factor]. / Radiosensibilité et séquelles neurologiques tardives suite à la radiochirurgie de malformation artérioveineuse : la SF2 comme nouveau facteur prédictif.

PURPOSE: To identify SF2 as a prognostic factor of late complications from radiosurgery in patients treated for AVM. PATIENTS AND METHODS: Five patients with AVM treated in three canadian institutions and who suffered clinically significant neurological sequelaes secondary to radiosurgery were identified. Their fibroblasts were cultured and their radiation sensitivity tested to determine the SF2 for each patient. RESULTS: Patients who developed a neurological complication from radionecrosis, secondary to radiosurgery had an SF2 different than the two control patients with AVM and no complications and also from a group of five cancer patients without late radiation complications (P = 0.005). CONCLUSION: Radiosurgery is an elective procedure. The identification of a subgroup of patients who are radiosensitive and at a higher risk of radiation induced complications can allow the treatment team to reduce the risk of such complications. SF2 as a new predictive factor should be incorporated in predictive models of risk from treatment of AVM by radiosurgery. This work needs to be confirmed in a larger cohort of patients.

Treatment planning aids in prostate cancer: friend or foe?

BACKGROUND: Rectal barium is commonly used as a treatment planning aid for prostate cancer to delineate the anterior rectal wall. Previous research at the Ottawa Regional Cancer Centre demonstrated that retrograde urethrography results in a systematic shift of the prostate. We postulated that rectal barium could also cause prostate motion. PURPOSE: The study was designed to evaluate the effects of rectal barium on prostate position. METHODS AND MATERIALS: Thirty patients with cT1-T3 prostate cancer were evaluated. Three fiducial markers were placed in the prostate. During simulation, baseline posterior-anterior and lateral films were taken. Repeat films were taken after rectal barium opacification. The prostate position (identified by the fiducials) relative to bony landmarks was compared before and after rectal barium. Films were analyzed using PIPsPro software. RESULTS: The rectal barium procedure resulted in a significant displacement of the prostate in the anterior and superior direction. The mean displacement of the prostate measured on the lateral films was 3.8 mm (SD: 4.4 mm) in the superior direction and 3.0 mm (SD: 3.1) in the anterior direction. CONCLUSIONS: Rectal barium opacification results in a systematic shift of the prostate. This error could result in a geographic miss of the target; therefore, alternate methods of normal tissue definition should be used.

[Effectiveness of doxorubicin-docetaxel or doxorubicin-cyclophosphamide combination in advanced breast cancer with distant metastasis]. / Doxorubicin + docetaxel-, illetóleg doxorubicin + cyclophosphamid-kezeléssel elérhetó eredmények távoli áttétet adó emlórákban.

Between June 1996 and March 1998 a multinational multicentric phase III randomised comparative study was made for comparing 1. the effectiveness, 2. the adverse events and 3. the quality of life of two combinations i.e. DD versus DC. 18 patients were treated with DD and 15 patients with DC. Age, tumour stage, visceral involvement, receptor status were well matched in the two groups. Good partial remission was obtained in 10 patients treated with DD whereas only seven remissions were seen in the DC arm. Response duration was similar in the 2 arms. No difference in adverse events was observed.

[The role of irinotecan in the treatment of advanced colorectal cancer] / Az irinotecan szerepe az elôrehaladott colorectalis carcinoma kezelésében.

PURPOSE: The purpose of the study was the evaluation of efficacy and the side effects of irinotecan in treatment of advanced colorectal cancer. METHODS: The authors presented their experiences with irinotecan in the treatment of 10 patients suffering from advanced colorectal cancer. The dose of irinotecan was 350 mg/m(2) every 21 days. Seven out of ten patients have taken oral fluoroquinolon to investigate its effect on the incidence of febrile episodes in case of febrile neutropenia. Three out of ten patients did not receive any antibiotic. The authors have examined the efficacy and safety of the treatment. RESULTS: One complete remission was obtained. Authors describe the observed side effects and the administered supportive care against serious complications. DISCUSSION: Serious diarrhoea has not been found in case of these 10 patients. The diarrhoea caused by irinotecan can be stopped by loperamide. The authors give accounts of early and following results.

A prospective comparison of three systems of patient immobilization for prostate radiotherapy.

PURPOSE: The study compared the setup reliability of 3 patient immobilization systems, a rubber leg cushion, the alpha cradle, and the thermoplastic Hipfix device, in 77 patients with cT1-T3, N0, M0 prostate cancer receiving conformal radiotherapy. METHODS AND MATERIALS: Port films were analyzed and compared to simulation films to estimate the setup errors in the three coordinate axes (anterior-posterior, cranial-caudal, medial-lateral). A total vector error was calculated from these shifts. RESULTS: The Hipfix was found significantly superior to the other two devices in reducing mean setup errors in all axes (p < 0.005). The average field-positioning error with the Hipfix ranged from 1.9 mm to 2.6 mm for all axes, whereas the deviation for the other two systems ranged from 2.7 to 3. 4 mm. Errors greater than 10 mm were virtually eliminated with the Hipfix system. There was a reduction in the mean total vector error in the alpha cradle and Hipfix patient cohorts over time, reflecting improved efficacy as a result of experience. CONCLUSION: There was a significant difference in the performance of each immobilization device. The Hipfix was consistently more reliable in reducing setup errors than the other devices.

[Irinotecan--experience with second-line treatment in advanced colorectal cancer] . / Irinotecan--második vonalbeli kezeléssel szerzett tapasztalatok elórehaladott colorectalis daganatokban.

The prognosis for patients with advanced colorectal cancer who fail to respond to a 5-FU based therapy is poor. About 7% response rate can be achieved with second line therapeutic regiments, the overall survival is about 6-7 months. The aim of authors was to assess the efficacy and toxicity profile of irinotecan (CAMPTO) in patients with advanced colorectal cancer, resistant to 5-FU based chemotherapy. From October 1996 to November 1998 19 previously treated metastatic colorectal cancer patients with documented progression were recruited. Irinotecan was given at a dose of 350 mg/m2 i.v. over 90 min. every 3 week. Tumor response and toxicity were assessed using WHO criteria. Median age: 59.7 years (42-72). Tumor sites: 12/19 colon, 7/19 rectum. 11/19 patients had 1 metastatic site, 8/19 had 2 or more metastatic sites. CR: 0/19, PR: 3/19, MR: 2/19, SD: 10/19, PD: 4/19. Median time to progression was 9.1 months (range 1.5-22). The overall median survival was 15.5 months (range 2.5-37). Grade 3-4 delayed diarrhoea occurred in 26.3% of patients. Grade 3 neutropenia occurred in 15.7% of patients. Preliminary results confirm the clinical value of irinotecan in 5-FU resistant metastatic colorectal cancer with tolerable toxicity profile. Irinotecan should be considered as the basic chemotherapeutic agent for second line treatment of metastatic colorectal cancer.

Respiratory-induced prostate motion: quantification and characterization.

PURPOSE: The precise localization of the prostate is critical for dose-escalated conformal radiotherapy. This study identifies and characterizes a potential cause of inaccurate prostatic localization-respiratory-induced movement. METHODS AND MATERIALS: Prostate movement during respiration was measured fluoroscopically using implanted gold fiducial markers. Twenty sequential patients with CT(1)-T(3) N(0) M(0) prostate carcinoma were evaluated prone, immobilized in customized thermoplastic shells. A second 20 patients were evaluated both prone (with and without their thermoplastic shells) and supine (without their shells). RESULTS: When the patients were immobilized prone in thermoplastic shells, the prostate moved synchronously with respiration. In the study the prostate was displaced a mean distance of 3.3 +/- 1.8 (SD) mm (range, 1-10.2 mm), with 23% (9/40) of the displacements being 4 mm or greater. The respiratory-associated prostate movement decreased significantly when the thermoplastic shells were removed. CONCLUSION: Significant prostate movement can be induced by respiration when patients are immobilized in thermoplastic shells. This movement presumably is related to transmitted intraabdominal pressure within the confined space of the shells. Careful attention to the details of immobilization and to the possibility of respiratory-induced prostate movements is important when employing small field margins in prostatic radiotherapy.

The efficacy of a combination of etoposide, ifosfamide, and cisplatin in the treatment of patients with soft tissue sarcoma.

BACKGROUND: Successful chemotherapy for patients with soft tissue sarcoma (STS) has been limited by a lack of active drugs. The most effective single agents are doxorubicin, dacarbazine, and, more recently, ifosfamide. Previously the most widely used combination has been CYVADIC (cyclophosphamide, vincristine, doxorubicin, and dacarbazine). In one randomized trial, ifosfamide was superior to cyclophosphamide; two nonrandomized studies also reported favorable results. Etoposide monotherapy was successful in 8%; the effectiveness of cisplatin was 5-23%. In view of these findings, the authors treated STS patients with an etoposide, cisplatin, and ifosfamide (VIP) combination. METHODS: The eligibility criteria included histologically confirmed, inoperable, metastatic or locally recurrent STS; a World Health Organization (WHO) performance status of 0-2; a maximum age of 75 years; and progressive, measurable disease. A total of 104 patients were treated from January 1990 to June 1997. The median age of the patients was 42.4 years. The patients were treated with a combination of etoposide (100mg/m(2) for 5 days), ifosfamide (2000 mg/m(2) for 2 days), and cisplatin (20mg/m(2) for 5 days) once a month via a peripheral vein. The treatment response and the toxicity were assessed according to WHO criteria. RESULTS: Of 104 evaluable patients, 47 responded. The overall response rate was 46% (complete response: 10%; partial response: 36%). In 43 patients the disease remained stable (41%). Remission duration was 4.6 months. Toxicity was moderate. The main adverse events were alopecia (100%), nausea and vomiting (73%), and leukopenia (29%). CONCLUSIONS: This new combination is promising for the treatment of patients with advanced STS.

Effects of urethrography on prostate position: considerations for radiotherapy treatment planning of prostate carcinoma.

PURPOSE: Retrograde urethrography is commonly used to define the prostate apex at simulation. This study evaluated the hypothesis that urethrography causes prostate displacement, resulting in an error in treatment planning. METHODS AND MATERIALS: Forty-five patients with carcinoma of the prostate were evaluated. Gold seeds were placed in the apex, posterior wall, and base of the gland. In the first 20 patients, the position of the seed-defined apex was compared at simulation (with urethrogram) and on day 1 of treatment (without urethrogram). In the second cohort of 25 patients, the effects of urethrography on prostate position were evaluated directly at simulation by comparing the position of apex pre- and post-urethrography. An analysis was performed to estimate the possible impact of urethrogram-induced prostate motion on target coverage. RESULTS: The mean superior displacement in the first and second cohort was 5.2 mm and 6.8 mm, respectively (combined mean shift 6.1 mm). With a 10-mm field margin below the tip of the urethrogram cone, 56% of patients in this study would have inadequate planning target volume (PTV) coverage. CONCLUSION: Retrograde urethrography causes a significant superior shift of the prostate. Strict reliance on urethrography in determining the inferior field margin could result in inadequate treatment.

Severe normal tissue complication correlates with increased in vitro fibroblast radiosensitivity in radical prostate radiotherapy: a case report.

The radiation responses of fibroblasts taken from four patients undergoing radiotherapy for prostate cancer were evaluated in vitro. One patient exhibited a severe normal tissue late reaction after radiotherapy, and the fibroblasts from this patient also showed increased radiosensitivity. The other three patients exhibited a normal clinical response, and their fibroblast response in vitro was also considered normal when compared with previously published data from our laboratory. When cells were allowed to repair potentially lethal damage (PLDR), the differences between cell lines were reduced; therefore, a deficiency in PLDR did not cause the differences in radiosensitivity. Fractionated radiation resulted in elevated survival due to repair of sublethal damage (SLDR), and the differences in radiosensitivity were increased. In addition, the survival curves displayed an upward bending nature, indicative of an adaptive response. Thus, adaptive response and ability to modify it may play an important role in fractionated radiotherapy. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 336-342 (2000).

Changes in apoptotic and mitotic activity in rectal carcinoma after short-term cytostatic therapy as possible predictive factors.

Fifteen patients with rectal adenocarcinoma were endoscopically biopsied and given short-term [5 fluorouracil (5FU) (600 mg/m2) and Ca-Folinate (60 mg/m2) for two days] cytostatic therapy. Seven days later the tumor was resected or a second biopsy was performed. Apoptotic and mitotic indices were determined in the tumor tissue before and after the short-term chemotherapy. The patients were treated thereafter with long-term, intermittent 5 FU administration and followed up clinically for 4-13 months. Three patients showed progression of the disease, twelve improved or showed no tumor progression. An increase of the apoptotic index and decrease of the mitotic index after the short-term cytostatic treatment were seen in the tumor tissue of responder cases. Non-responders showed increase or no change in mitotic activity, and decrease or no change in apoptotic activity. These findings suggest that apoptotic and mitotic response to short-term cytostatic therapy may be additional predictive factor in rectal adenocarcinoma.

Maintenance treatment with medroxyprogesterone acetate in patients with advanced breast cancer responding to chemotherapy: results of a randomized trial. Essen Breast Cancer Study Group.

The purpose of this randomized phase III trial was to study whether medroxyprogesterone acetate (MPA) maintenance treatment prolongs the time to progression in advanced breast cancer patients responding to an induction chemotherapy. Patients with progressive advanced breast cancer previously untreated with anthracylines and progestins were given epirubicin (30 mg/m2) and ifosfamide (2 g/m2) on days 1 and 8 at 3-weekly intervals. Patients without disease progression after 6 cycles of chemotherapy were randomly assigned to receive, until progression, either no treatment or MPA at a daily total dose of 500 mg. Ninety patients were randomized: 46 to the MPA arm and 44 to the observation arm. Median time to progression was longer in the MPA arm: 4.9 months versus 3.7 months in the intent-to-treat analysis (p = 0.02), and 4.9 months versus 3.0 months in the secondary efficacy analysis (p = 0.012). Seven patients were removed from MPA due to side effects. The changes in patient-rated quality of life scores were similar in both groups. The median length of survival from randomization was 17.4 months for patients receiving MPA and 18.3 months for patients randomized to observation (p = 0.39). In conclusion, in patients with advanced breast cancer achieving remission or non-progression with 6 cycles of epirubicin and ifosfamide chemotherapy, MPA maintenance treatment led to a significant, though modest, prolongation of the time to progression without affecting overall survival of the study patients.

[Low-dose leucovorin and interferon-alpha as modulators of 5-fluorouracil for adjuvant chemotherapy of colorectal cancer]. / Colorectalis carcinomák kis dózisú leukovorin és interferon-alpha modulált adjuváns 5-fluorouracil kemoterápiája.

It has recently been published the results of a prospective, comparative study for adjuvant chemotherapy of 164 colorectal cancer patients. Pathological stages were Dukes B 79, C 85 of the cases. The site of primary tumour was colon 108, rectum 56 of the patients. The treatment protocols were as follows: 425 mg/m2 5-fluorouracil plus 20 mg/m2 leucovorin on days 1-5 at 28 days cycles six times (LV group). The IFN group received the same chemotherapy completed with weekly 3 x 3 MIU interferon alpha. Both treatment groups were well balanced. The mean follow up time was 38.1 months. There were 91 patients of relapse and 65 deaths this time. The time to progression was 15 months in the LV group and 12.7 months in the IFN group (p < 0.05). The mean survival time was 24 months in the LV group compared to 22.3 of the IFN group. The frequency and sites of relapses did not differ statistically between the both groups. The preoperative CEA-level was elevated in 42 cases. The mean survival time was 26.4 months in the cases having normal CEA-level compared to 16.1 months of the cases with high-level (p < 0.001). The side-effects were transient and mild, while in the group treated with interferon were more instances of fever, fatigue, flu-like syndrome, psychic disorders, depression and agitation. The administration of interferon had to be interrupted in 4 cases. The results of interim analysis suggest choosing the so-called Mayo protocol for the standard adjuvant treatment of colorectal cancer.

Epirubicin and ifosfamide in metastatic breast cancer.

In a randomized, phase II trial, we evaluated the effectiveness of continued chemotherapy with epirubicin/ ifosfamide versus unmaintained treatment interruption in advanced metastatic breast cancer. Three hundred fifty-seven patients were enrolled and 331 were evaluable for response. Complete response was achieved in 25 patients (8%) and partial response in 121 patients (37%). Pretreatment status correlated significantly with response (complete and partial response). While 54% of unpretreated patients responded, only 42% of the patients responded who had been pretreated with adjuvant chemotherapy and 33% who had been pretreated in the metastatic stage of disease; 69 patients (21%) had disease progression. Of 11 patients pretreated in both the adjuvant and metastatic setting, only two responded. Toxicity of treatment was mild, with leukopenia being the treatment-limiting factor. Thrombocyte levels were not altered significantly by treatment. Thus, there seems to be room for dose escalation using granulocyte colony-stimulating factor. There was no considerable cardiotoxicity, central nervous system toxicity, or cystitis observed. The low rate of cardiotoxicity appeared to be related to dose fractionation of epirubicin. After randomization of patients to treatment interruption versus continuation of chemotherapy, a longer relapse-free survival was observed for patients who continued chemotherapy (mean relapse-free survival, 2+ months); however, this did not translate into prolonged survival. The cumulative scores of toxicity and quality of life parameters showed increasing superiority for treatment interruption. Therefore, a strategy of treatment until maximum response and subsequent treatment interruption seems to be superior to treatment continuation.

Lateral electron equilibrium and electron contamination in measurements of head-scatter factors using miniphantoms and brass caps.

The head-scatter factor (Sh) can be measured with a narrow miniphantom or a metal cap provided it is completely covered by the photon beam and its lateral size is thick enough to prevent electron contamination contributions. The effects of lateral electron equilibrium (LEE) and electron contamination on the Sh values were studied. The EGS4 Monte Carlo technique was used to calculate the minimum beam radii (rLEE) required to achieve complete LEE for photon beams ranging from 60Co to 24 MV. The measurement shows that the error introduced to the Sh value due to lateral electron disequilibrium is negligible. The radii of the miniphantoms or the sidewall thicknesses of the caps can be reduced below rLEE provided they are thick enough to prevent the effect of electron contamination.

Asymmetric arc technique for posterior pharyngeal wall and retropharyngeal space tumors.

PURPOSE: Tumors of the posterior pharyngeal wall and nasopharyngeal cancer with retropharyngeal extension can partly encircle the cervical vertebrae. Treating the patient within spinal cord tolerance can cause a geographic miss. A simple technique has been developed to avoid this problem. METHODS AND MATERIALS: The standard fields for posterior pharyngeal wall and nasopharyngeal tumors are used up to 36-40 Gy. A planning computed tomography (CT) scan is taken during the second or third week of treatment with the patient fitted in a new shell ensuring that the cord is straight and parallel to the treatment couch. The asymmetric arc technique consists of two posterior arcs with closure of one jaw beyond the central axis. Each arc delivers the total dose to each ipsilateral side, while the median region of the U-shaped volume is treated by the summation of both arcs. RESULTS: We have treated 10 patients using asymmetric arcs in the last 3 years. This technique proved to be a versatile way of treating targets wrapped around the spine. The technique allows better individualization for target volume irregularities than the partial rotation with a central bar.