Victy Y.W. Wong

Salvage radiation therapy for locally recurrent nasopharyngeal carcinoma

PURPOSE To study the treatment outcome in patients with locally recurrent nasopharyngeal carcinoma (NPC) and to explore whether a combination of high-dose-rate (HDR) intracavitary brachytherapy and external beam radiation therapy (ERT) could improve the therapeutic ratio. METHODS AND MATERIALS Ninety-one patients with nonmetastatic locally recurrent NPC who were treated with curative intent during the years 1990-1999 were retrospectively analyzed. Eighty-two patients had histologically proven carcinoma. The remaining 9 had clinical and imaging features suggestive of local recurrence. The Hos T-stage distribution at recurrence (rT) was as follows: rT1-37, rT2-14, rT3-40. Total equivalent dose (TED) was calculated by the linear-quadratic formula without a time factor correction. For those treated by combined-modality treatment (CMT), the TED was taken as the summation of the equivalent dose by ERT and the absolute dose delivered to floor of the sphenoid by brachytherapy. Eight patients were treated solely with brachytherapy, all receiving 24-45 Gy in 3-10 sessions. Forty-one patients were treated with ERT alone receiving a median TED of 57.3 Gy (range, 49.8-62.5 Gy). Forty-two patients were treated by CMT with a median equivalent dose of 50 Gy (range, 40-60 Gy) given by ERT and 14.8 Gy by brachytherapy (range, 3-29.6 Gy). Multivariate analyses were performed using the Cox regression proportional hazards model. RESULTS The 5-year actuarial overall survival rate, disease specific survival rate and local failure-free survival (LFFS) rate for the whole group were 30%, 33. 3% and 37.8%, respectively. The 3-year LFFS rates of rT1, rT2, and rT3 diseases were 64%, 61.5%, and 18.4%, respectively (p = 0.001). Of the 8 patients treated with brachytherapy alone, 4 failed locally. Further analyses were concentrated on the ERT (41 patients) and CMT (42 patients) groups. The 3-year LFFS rates of rT1, rT2, and rT3 diseases were 66.7%, 66.7%, and 18.4%, respectively (p = 0.0008). Better local control for patients who received a TED of 60 Gy or greater was shown. The corresponding 3-year LFFS rates were 29% and 60% (p = 0.0004). Subgroup analysis on the ERT and CMT groups showed a 3-year LFFS rate of 33.5% and 57% (p = 0.003). ERT group had an excess of patients with rT3 disease. Further analysis was performed on the rT1-2 patients showing a trend toward improvement in local control in favor of the CMT group (3-year LFFS rates: CMT, 71.7%; ERT, 54%; p = 0.13). Multivariate analyses showed that rT stage (p = 0.002) and TED (p = 0.01; HR, 0.93; 95% confidence interval, 0.88-0. 98) remained significant. The 5-year major and central nervous system (CNS) complication-free rates were 26.7% and 47.8%. The following factors were found to be significant on univariate analyses for both complications in the ERT and CMT groups: (1) Modality of treatment: more complications with ERT group; and (2) rT stage. Multivariate analyses showed that the rT stage was significant for predicting the occurrence of major (p = 0.004) and CNS complications (p = 0.04). CONCLUSION For rT1-2 local recurrences, CMT with at least 60 Gy TED is recommended. The high incidence of major late complications is of serious concern. Ways of improving the local control of Hos rT3 disease and reducing the risk of late complications should be explored.

Salvage brachytherapy for patients with locally persistent nasopharyngeal carcinoma

PURPOSE Locally persistent nasopharyngeal carcinoma (NPC) carries an increased risk of local failure if additional treatment is not given. This study was conducted to evaluate the outcomes of patients with locally persistent NPC as treated by high-dose-rate (HDR) intracavitary brachytherapy, and to explore whether routine brachytherapy boost could improve the local control. METHODS AND MATERIALS Eighty-seven patients with locally persistent NPC treated during 1990-1998 with HDR intracavitary brachytherapy were retrospectively analyzed. Fibreoptic nasopharyngoscopy was performed 3-6 weeks after completion of the primary external radiation therapy (ERT). Biopsies were only taken from suspicious areas. Those with complete regression of local disease were put on observation. Eighty-seven patients were shown to have persistent viable disease at a median time of 6 weeks post-RT. The distribution according to Hos staging system at initial diagnosis was as follows: Stage I-8, II-33, III-41, IV-5; T1-19, T2-48, T3-20; N0-32, N1-22, N2-28, N3-5. CT scan for restaging was not performed after the documentation of persistent disease. Our policy was to treat all patients with persistent disease with brachytherapy irrespective of the extent of disease just prior to brachytherapy. They were treated with HDR intracavitary brachytherapy, with either cobalt sources or an iridium source, giving 22.5-24 Gy in 3 weekly sessions in all but 4 patients. This dose was prescribed at a distance of 1.5 cm from the center of the surface as defined by the sources in the first six patients and subsequently reduced to 1 cm for the others. Twelve patients were treated with neoadjuvant chemotherapy. To compare the efficacy of brachytherapy, another 383 consecutive nonmetastatic patients, treated with curative intent by ERT, during the years 1990-1993, were evaluated. Multivariate analysis was performed using the Cox regression proportional hazards model. RESULTS The 5-year actuarial local failure-free survival (LFFS) rates and disease-specific survival rates for the brachytherapy group and ERT group were 85% and 76.6% (p = 0.15), and 72% and 67.8% (p = 0.2), respectively. The corresponding 5-year actuarial LFFS rates for T1, T2, and T3 disease were 94.7%, 88.2%, 67.4%, and 84.1%, 79.8%, 62.6%. In assessing the local control, only the T staging was significant on multivariate analysis (p = 0.0004). Other parameters such as age, sex, and persistence of disease (giving brachytherapy) were all nonsignificant. Complications were comparable between the two groups. In the persistent group, the local failure rates of the patients treated with and without neoadjuvant chemotherapy were 17% (2/12) and 13% (10/75) respectively. When analyzed according to different brachytherapy sources, the 5-year LFFS rates of the T1, T2, and T3 patients treated with iridium and cobalt sources were 100% vs. 85.7 (p = 0.19), 93.6% vs. 70% (p = 0.04), and 67.7% vs. 60% (p = 0.72). The difference was statistically significant for the T2 groups. When early T-stage (T1 and T2) patients were grouped together for analysis, the iridium group again showed a statistically significant improvement in 5-year LFFS rate when it was compared with the cobalt group (95.3% vs. 76.5%, p = 0.03) and the ERT alone group (95.3% vs. 81.5%, p = 0.03). The improvement of local control is attributed to a higher nasopharyngeal mucosal dose that is achieved by using small-size flexible applicators with an iridium source. It is interesting to note that the 5-year LFFS rates for the ERT alone group (T1: 84.1%, T2: 79.8%, T3: 62.6%) are comparable to the corresponding rates of the cobalt group. This information supports our speculation that an adequate booster treatment could compensate for inadequate primary treatment. The prognosis of patients with locally recurrent NPC is grave. Maximizing the local control is therefore crucial for the survival of the patients. (ABSTRACT TRUNCATED)

Hypofractionated stereotactic radiotherapy for medically inoperable stage I non-small cell lung cancer – report on clinical outcome and dose to critical organs

We report 20 cases using hypofractionation stereotactic radiotherapy in medically inoperable stage I non-small cell lung cancer with dose escalation of 45-54 Gy prescribed at 85 or 90% isodose level in 3-4 fractions. Two-year local control and cancer-specific survival were 94.7 and 77.6%, respectively, with minimal toxicity. Though, large fraction size can be safely given to peripheral lung tumors, normal tissue tolerance to hypofractionated radiotherapy to esophagus, trachea, main bronchi, aorta and heart remains unknown. Therefore we also reported the maximum point doses to these critical organs to contribute information to extend this technique to more centrally located lung tumors in future.

Treatment results of high-dose-rate remote afterloading brachytherapy for cervical cancer and retrospective comparison of two regimens

PURPOSE To review the treatment results and complications of high-dose-rate (HDR) intracavitary brachytherapy for patients with carcinoma of the cervix in a single institute and to compare them with those of low-dose-rate (LDR) brachytherapy reported in the literature. METHODS AND MATERIALS Two hundred twenty patients with carcinoma of the cervix were treated by primary radiotherapy between 1991 and 1998. The median age was 63 (range 24-84). The distribution according to Federation of Gynecology and Obstetrics (FIGO) staging system was as follows: Stage IB, 11.4%; IIA, 9.1%; IIB, 50.9%; IIIA, 3.6%; IIIB, 23.2%; and IVA, 1.8%. They were treated with whole pelvic irradiation giving 40 Gy to the midplane in 20 fractions over 4 weeks. This was followed by parametrial irradiation, giving 16-20 Gy in 8-10 fractions. HDR intracavitary brachytherapy was given weekly, with a dose of 7 Gy to point A for three fractions and, starting from 1996, 6 Gy weekly for four fractions. The median overall treatment time was 50 days (range 42-73 days). The median follow-up time was 4.7 years (range 3 months to 11.1 years). Multivariate analysis was performed using the Cox regression proportional hazards model. RESULTS The complete remission rate after radiotherapy was 93.4% (211/226). The 5-year actuarial failure-free survival (FFS) and cancer-specific survival (CSS) rates for stage IB, IIA, IIB, IIIA, IIIB, and IVA were 87.7% and 86.6%, 85% and 85%, 67.8% and 74%, 46.9% and 54.7%, 44.8% and 50.4%, 0% and 25%, respectively. On multivariate analysis, young age (< 50) (p = 0.0054), adenocarcinoma (p = 0.0384), and stage (p = 0.0005) were found to be independent poor prognostic factors. The 5-year actuarial major complication rates (Grade 3 or above) were as follows: proctitis, 1.0%; cystitis, 0.5%; enteritis, 1.3%; and overall, 2.8%. On multivariate analysis, history of pelvic surgery was a significant prognosticator. The two HDR fractionation schedules were not a significant prognosticator in predicting disease control and complications. CONCLUSION Our experience in treating cervical cancer with HDR intracavitary brachytherapy is encouraging. Our treatment results and complication rates were compatible with those of the LDR series. Further studies are eagerly awaited to better define the optimal fractionation schedule for HDR brachytherapy and the schedule on how chemotherapy may be combined with it.

HIGH DOSE RATE INTRACAVITARY BRACHYTHERAPY IN THE TREATMENT OF NASOPHARYNGEAL CARCINOMA

A retrospective study on 61 patients, with local persistent or recurrent nasopharyngeal carcinoma (NPC), treated during 1990-1992 with high dose rate intracavitary brachytherapy alone or combined with external irradiation, is presented. All 39 patients with persistent disease were treated solely with brachytherapy. The actuarial 3-year local failure-free survival (LFFS) rates of the persistent and recurrent groups were 82% and 45% respectively. The corresponding disease specific survival rates were 82% and 62%. Fifteen patients with recurrence received the combined modality treatment and their 3-year LFFS rate was 65%. Three out of 7 patients treated by brachytherapy could be controlled locally. The total dose given to the floor of sphenoid was an important predictor of local control. Of the 23 patients with persistent disease treated with < 17.5 Gy to this area, 6 failed locally as opposed to none of the 16 patients receiving a higher dose (p = 0.031). For those with recurrence treated by the combined modality, none of the 7 patients given >/= 57.5 Gy recurred while 5 local failures were observed among those receiving a smaller dose (p = 0.041). The general implications of these results for the treatment of NPC recurrence are discussed.

High dose rate brachytherapy for carcinoma of the oral tongue

PURPOSE The purpose of this study is to assess the feasibility of treating early-staged tongue cancer with high dose rate (HDR) remote afterloading technique. Furthermore, a new figure of merit, the Geometry Index (GI), is introduced to quantify the quality of the implants. METHODS AND MATERIALS Between 1994 and 1995, eight patients with carcinoma of the oral tongue were treated solely with interstitial implant using the HDR remote afterloading technique. Five patients had T1 N0 disease and the remaining three had T2 N0 disease. Elective neck treatment was withheld. The male-to-female ratio was 1:1, and the mean age 60 years (range: 32-72 years). The median follow-up time was 26 months (range: 6-30 months). The afterloading catheters were positioned through the submandibular approach with the assistance of templates. Six patients had single planar implant and the remaining two had double planar implant. The median number of catheters inserted was 5 (range: 4-9). The median dose given was 60 Gy in 10 fractions over 6 days. The interfraction interval was 7 h. Mandibular and maxillary shields were inserted prior to treatment. Thomadsen et al. introduced the use of Implant Quality Index (QI). We introduce a new parameter, GI, which is defined as ratio of the QI of the nonoptimized executed implant to the corresponding QI value of the nonoptimized idealized implant. RESULTS The mucositis lasted for 6 to 20 weeks (median: 10 weeks). There was no local failure up to a median follow-up of 26 months. Two patients developed ipsilateral neck node metastases at 2 and 4 months following implant, respectively. One patient had involvement at level II and the other failed at level I to III. Both patients were salvaged by neck node dissection and regionally remained in control. One patient with multiple nodal metastases and extracapsular spread developed biopsy-proven liver metastases and succumbed 6 months following implant. One patient treated with double planar implant developed Grade 3 necrosis of the soft tissue and bone. This complication is largely preventable now, as we have acquired more technical expertise. The mean GI values for the single and double planar implants were 0.88 (range: 0.84-0.91) and 0.8, respectively. This correlates with our practical experience that it is more difficult to maintain a good geometry as double planar implant is required. The GI gives a better view of the geometry of implant as it compares the nonoptimized QI of the executed implant with its ideal counterpart. The failure to achieve a high GI in double planar implants is presumed to relate to technical difficulties rather than variation in individual performance. CONCLUSION Our preliminary experience in treating early-staged tongue cancer with the HDR remote afterloading technique is inspiring, as it gives a local control rate of 100% with acceptable morbidity. Further studies are eagerly awaited to delineate the optimum schedule for this modality of treatment. It is hoped that the GI values, which represents the skills of insertion, could be routinely reported so that treatment results between different centers could be compared in a more precise manner.

Stereotactic Radiotherapy for Locally Recurrent Nasopharyngeal Carcinoma

PURPOSE To study the treatment outcome in patients with locally recurrent nasopharyngeal carcinoma (NPC) who were treated with stereotactic radiotherapy (SRT). METHODS AND MATERIALS Thirty patients with non-metastatic, locally recurrent NPC who were treated with curative intent between 1998 and 2002 were retrospectively analyzed. The International Union Against Cancer T-stage distribution at recurrence (rT) was as follows: rT1-14, rT2-7, rT3-3, and rT4-6. All patients were treated with SRT with a daily fractional dose of 2.5-4.5 Gy (median, 3 Gy) in 8-22 fractions (median, 18 fractions). Total equivalent dose (TED) was calculated by the linear-quadratic formula without a time factor correction. RESULTS The 5-year actuarial overall survival rate, disease-specific survival rate, and local failure-free survival (LFFS) rate for the whole group were 40%, 41.4%, and 56.8%, respectively. The 3-year LFFS rates of rT1-2 and rT3-4 diseases were 65% and 66.7%, respectively. Seven of nine patients who received a TED <55 Gy recurred locally compared with 4 of 21 patients who received > or =55 Gy. Their corresponding 5-year LFFS rates were 22.2% and 75.8% (p = 0.005). The TED was the only factor significant in affecting the local control on univariate analyses. CONCLUSION SRT is an effective treatment for locally recurrent NPC. TED > or =55 Gy should be given to secure a higher local control rate. The late complication rates were acceptable for patients with rT1-2 disease. For patients with rT3-4 disease, more works need to be done to further decrease the late complications.

High dose rate brachytherapy for early stage oral tongue cancer

High dose rate (HDR) interstitial brachytherapy of the oral tongue is a new treatment modality. Our study evaluates the outcomes of patients with early stage oral tongue cancer as treated by HDR interstitial implant.

Nasopharyngeal intracavitary brachytherapy: the controversy of T2b disease.

Locally persistent nasopharyngeal carcinoma (NPC) carries an increased risk of local failure if additional treatment is not given. It has been shown that intracavitary brachytherapy is effective in the treatment of patients with T1 and T2a NPC, although its role in the treatment of T2b disease had remained uncertain. The objectives of the current study were to evaluate the outcomes of patients with T2b, locally persistent NPC who were treated with high‐dose‐rate (HDR) intracavitary brachytherapy and to explore whether routine brachytherapy boost could improve the local control of patients who had T2b NPC at initial diagnosis.

CT Verification of Isocentre Relocatability Using Stereotactic Mask Fixation System

AIMS This study introduces a non-invasive method based on computed tomography (CT) verification to ensure patients are accurately positioned before fractionated stereotactic radiotherapy. It enables quality control of mask positioning with reference to the CT images of the treatment plan. MATERIALS AND METHODS A mask system, together with a dental impression moulded mouth bite, was used for patient immobilisation. In order to facilitate relevant image comparison, special alignment during CT localisation was discussed in the study. The accuracy of patient set-up was studied by assessing the isocentre position in relation to the patients anatomical structure. The planning CT images were applied as a reference and the study was applied to 261 cranial applications. RESULTS The results show that the mean and the maximum overall displacements at the isocentre were 0.7 and 2.5 mm, respectively. The mean and the maximum rotational displacement in the axial plane were 0.56 degrees and 2 degrees, respectively. The mean translational displacement and rotational displacement were close to zero when considering the direction of movement. CONCLUSIONS The results indicate that the systematic error of the mask system and the verification method are minimal. Advantages of this technique include the simple set-up, three-dimensional quantification and short study time (10-15 min). It is therefore practical to implement on a routine basis. Investigation of the ability to relocate the mask is also recommended to justify the required safety margin between the clinical and planning target volumes.