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A Comparison of Dose Distribution from Two Different Intracavitary Brachytherapy Applicator Systems in Cervical Carcinoma
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Abstracts / Brachytherapy 9 (2010) S23eS102
all patients were alive, and no local failures had occurred. Acute toxicities were mild. One grade >3 late event occurred, consisting of meningitis requiring hospitalization.
capability to shape the device to the needed dimensions intraoperatively may be an important advantage over prefabricated dural plaques. A highdose-rate dural boost may also provide dosimetric advantages when planning postoperative external beam radiation, particularly in patients who have previously been irradiated and the spinal cord tolerance is a significant concern. Further work will be necessary to substantiate whether these advantages will result in improved patient outcomes.
GYNECOLOGICAL POSTERS ThursdayeSaturday PO17
Conclusions: Treatment of HGG with the MammoSiteÒ and ConturaÔ devices is technically feasible. Though our initial clinical experience is encouraging, the safety and efficacy of these devices need to be tested in a larger cohort.
PO16 A Novel Application of 32P for High-Dose-Rate Brachytherapy of the Dura During Decompressive Spine Radiosurgery Yoshiya Yamada, M.D.1, Marco Zaider, Ph.D.2, Thomas Golembeski, M.S.3, Lawrence Dauer, Ph.D.2, Mark H. Bilsky, M.D.4 1Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY; 2 Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY; 3IBA Radioisotopes, Inc., Pleasanton, CA; 4Neurosurgery, Memorial Sloan-Kettering Cancer Center, New York, NY. Purpose: The dura is often contaminated with tumor cells in the setting of epidural extension of tumor, even after excellent surgical decompression of epidural disease. Despite the inherent dosimetric benefits of brachytherapy, traditional brachytherapy sources have not been used in regular practice to irradiate the dura. This may be due to excessive dose to the spinal cord or technical concerns which make it impractical. Phosphorus 32 (32P), a beta emitting isotope, was imbedded into a thin flexible soft plastic film in order to deliver high dose extremely short range radiation to the dura. The device has FDA clearance. Materials and Methods: The P32 film is approximately 0.35 mm thick and can deliver a dose of approximately 1 Gy per minute at the surface. After surgical decompression of epidural tumor, a non radioactive blank is cut to the desired shape and size. The blank is overlaid on the actual radioactive film in a water bath. The actual film is then cut to same shape and size, using the blank as a guide. The radioactive film is then carefully placed on the dural surface and left in place until the desired dose is delivered. When there is at least 3 mm of cerebral spinal fluid, a dose of 10 Gy to the dura will deliver less than 1 Gy to the surface of the underlying spinal cord. Results: Two patients have undergone intraoperative 32P dural brachytherapy. In each case, the patient had epidural cord compression requiring surgical decompression and had previously been irradiated at the site. A dose of 10 Gy was prescribed to the surface of the dura. Postoperative image-guided radiotherapy was delivered, taking into account the dose given to the dura. Because of the intraoperative brachytherapy boost, aggressive dosing near the spinal cord during external beam radiation treatment planning was not necessary, improving PTV coverage of the remainder of the volume by 10-20%. No post operative complications have been encountered. The followup is less than 2 months for both patients. Conclusions: Although the experience with the use of a 32P film for dural brachytherapy is very preliminary, it appears to be safe. The flexibility and
A Comparison of Dose Distribution from Two Different Intracavitary Brachytherapy Applicator Systems in Cervical Carcinoma Bishan Basu, M.D., Bikramjit Chakraborti, M.D., Suman Ghorai, M.D., Koushik Ghosh, M.Sc. Radiotherapy, Medical College Hospital, Kolkata, West Bengal, India. Purpose: Brachytherapy is an integral component of curative radiation therapy for the treatment of cervical carcinoma. Although intracavitary brachytherapy (ICBT) is the commonly performed procedure, during ICBT, the choice of applicator system (e.g., Fletcher-Suit, Manchesterstyle, Ring applicator, etc.,) is somewhat arbitrary. But, we thought that applicator geometry may play an important role in dose distribution. And, it may be possible to increase the therapeutic ratio (by selectively sparing the organs-at-risk eg. urinary bladder and rectum) by using one applicator over another. Materials and Methods: Patients suffering from locally advanced cervical carcinoma (unoperated) with ECOG Performance Status 0 or 1 without any other significant co-morbid conditions were enrolled for the study between July 2007 and December 2008. Patients who had contraindications to ICBT were excluded. 22 patients were selected. After completion of EBRT to the whole pelvis, patients underwent intracavitary brachytherapy with tandem and ovoid applicators. Two different types of CT-compatible applicators were used: Manchester-style and Fletcher-style applicators (Varian Medical Systems, Inc., Palo Alto, CA). The purpose was to compare the dose distribution obtained when two different applicators were applied to the same patient. So, in a given patient, if on the first insertion, Manchester-style applicator was used, Fletcher-style applicator was used on the next occasion and vice versa. The sequence of applicator was decided randomly (coin method). Based on the CT scan image of the whole pelvis in the treatment position with the applicator in place, dose was prescribed to Point A (Point H, according to ABS). To maintain comparability, for all insertions, a dose of 8 Gy was prescribed to the leftsided Point A. After adequate optimization the bladder and rectum doses (at ICRU point, 0.1cc, 1.0cc and 2cc volumes) were noted. Also the 100% isodose curve characteristics (maximum height, width & thickness of the 100% isodose curve, the 100% isodose volume as well as the width & thickness of the 100% isodose curve at the level of Point A) were noted. All data were analyzed using appropriate statistical test, i.e., Paired t test. Results: Regarding the 100% isodose characteristics, the 100% isodose volume and the maximum width of the 100% isodose curve were significantly greater (P value !.0001 in both occasions) when Manchester-style applicator was used. However, the dose received by 0.1 cc, 1.0 cc and 2.0 cc of the urinary bladder were also significantly greater (P value !0.0001) with the Manchester-style applicator. No significant difference was found in the rectal doses. Conclusions: The larger 100% isodose volume as well as the greater width of the 100% isodose curve achieved with the use of Manchester-style applicator can be helpful in circumstances where the disease is bulky. However this must be balanced against the increased dose received by the urinary bladder when the same applicator is used. This data must be correlated clinically before coming to any final decision. For clinical correlation, we are collecting relevant data from patients where the Manchester-style applicator was used and comparing them with data received from patients where the Fletcher-style applicator was used. After
Abstracts / Brachytherapy 9 (2010) S23eS102 detailed evaluation and statistical analysis of those data, we may reach a more confident conclusion. PO18 The Impact of Bladder Volume Variations on the Highest Bladder Dose Point Location During HDR Brachytherapy for Cervix Cancer Francois Bachand, M.D., Christina Aquino-Parsons, M.D., Rustom Dubash, M.S., Conrad Yuen, M.Sc., Peter Lim, M.D. Radiation Oncology, Vancouver Cancer Center, BC Cancer Agency, Vancouver, BC, Canada. Purpose: Intracavitary brachytherapy is an essential component of cervical cancer treatment. This treatment can result in a high dose to the bladder wall leading to radiation cystitis. Variations in bladder volume can result in changes in the high dose region of the bladder. We hypothesized that the location of the bladder high dose region varies in both location and dose with variations in bladder volume. Materials and Methods: A retrospective analysis of all HDR brachytherapy planning CT scans was performed in our center. Patients whose multiple scans demonstrated a considerable difference in bladder volume were selected for this analysis. A tandem and ring applicator was used for all implants. All patients were re-planned with standard loading, delivering 600 cGy at Point A. The location (coordinates and quadrants) and the intensity of the maximum bladder dose were compared between the small and large bladder volume scans using the paired t-test. The dose at the maximum bladder dose point defined in the small bladder group was assessed in the larger bladder scans. Results: 10 patients met the inclusion criteria with a mean difference of 191 cc in bladder volume. Mean bladder volume for the small bladder group was 141 cc vs 332 cc for the large bladder group (p ! 0.001). The mean bladder maximum dose point was 798 vs 1102 cGy for the small and large bladder groups respectively (p 5 0.028). The location of the maximum dose point changed quadrants in 7/10 patients. This translation was not demonstrated by the coordinate variation, Y 0.56cm (p 5 0.219) and X 0.24cm (p 5 0.381). The location and the dose of the hotspot did not change in the two patients with the smallest bladder volume difference. However, when the bladder volume difference was greater, the maximum bladder dose point identified in the small bladder group received less dose when the bladder was large (mean difference of 155 cGy, p 5 0.081). Conclusions: The location of the maximum dose point on the posterior wall of the bladder changes with bladder volume variation. With a larger bladder volume, the dose at the maximum dose point increases, but the dose at the maximum bladder dose point identified on the small bladder scans decreases. We hypothesize that bladder filling variations between implants, resulting in changes in the location of the high dose in the bladder, will lead to a decrease in radiation cystitis. We plan to look at this prospectively. PO19 Retrospective Analysis of Toxicity from Vaginal Cuff Brachytherapy Bruce Libby, Ph.D.1, Neil Sen, B.S.2, Bernard F. Schneider, Ph.D., M.D.1 1 Radiation Oncology, University of Virginia, Charlottesville, VA; 2School of Medicine, University of Virginia, Charlottesville, VA. Purpose: In order to determine both the efficacy and toxicities associated with post operative vaginal cuff brachytherapy, patient’s medical records were analyzed to determine rates of complications as well as recurrence rates. Materials and Methods: Medical records of 207 patients who received vaginal cuff brachytherapy at the University of Virginia were examined to compile the rates of radiation induced toxicities. Custom made clear acrylic cylinders of 2.3, 2.6, 3, 3.5, and 4 cm diameter were used, with the cylinder visually confirmed to be centered along the scar. Standard plans for each cylinder size were used, with a treatment length of 4 cm and the dose prescribed to 0.5 cm from the wall of the cylinder. The prescription was 7 Gy/fraction for 3 fractions, delivered 1 week apart. Vaginal cuff brachytherapy was the only radiation treatment used. Data were obtained immediately following the completion of brachytherapy, and at 6,12, 24, and >48 months post treatment.
S87
Results: Of the 207 patients, 144 (69.6%) experienced no radiation induced toxicities at any time. Of the patients who experienced toxicities, vaginitis/ discharge (10.6%) and vaginal stenosis/agglutination (9.7%) were the most prevalent, and most occurred soon after the completion of treatment. Eight patients experienced recurrence of the cancer: 1 patient (0.5%) experienced vaginal vault recurrence, 6 patients (2.9%) had abdominal or pelvic recurrence, and 1 patient (0.5%) had a distant metastasis. Conclusions: A retrospective analysis of adjuvant vaginal cuff brachytherapy shows that the treatment does not result in significant toxicities, and appears to be highly effective in preventing vaginal cuff recurrences following surgery for endometrial cancer.
PO20 High-Dose-Rate Interstitial Brachytherapy in the Management of Carcinoma of The Bartholin Gland: A Single Institution Experience with Long-Term Followup Isabelle Thibault, M.D., Marie-Claude Lavallee, M.Sc., Janelle Morrier, M.Sc., Eric Vigneault, M.D., M.Sc. Radiation Oncology, Centre Hospitalier Universitaire de Que´bec (CHUQ) - L’Hoˆtel-Dieu de Que´bec, Quebec, QC, Canada. Purpose: Carcinoma of the Bartholin gland is a rare malignancy considered by some as part of the vulvar cancers and by others as a distinct entity. Traditional therapeutic approach includes surgery but treatment algorithm including other modalities hasn’t been well defined. The purpose of this study is to assess the role, efficacy and toxicities of high-dose-rate (HDR) interstitial brachytherapy (ISBT) in the management of Bartholin’s gland cancer at L’Hoˆtel-Dieu de Que´bec. Materials and Methods: Between 2001 and 2009, three patients received HDR-ISBT for carcinoma of Bartholin’s gland and were retrospectively reviewed. The implantation procedure consisting of catheter insertion under fluoroscopic guidance through a Syed-Neblett template was performed under general anesthesia. After the procedure, a CT scan was done and dosimetry optimization was performed using inverse planning simulated annealing (IPSA) algorithm. The first treatment was delivered the same day using a HDR remote afterloading system and subsequent fractions were given twice a day. For each woman, tumor and treatment characteristics as well as reasons for ISBT were recorded. RECIST criteria were used to evaluate patient’s response to therapy. Overall survival (OS) and disease-free survival (DFS) were analyzed. Dosevolume histograms (DVH) were generated and doses were converted to equivalent dose in 2-Gy (EQD2). Total EQD2 doses of ISBT and external beam radiation therapy (EBRT) were calculated, with a/b ratio of 10 for tumor and of 3 for normal tissues. DVH parameters for organs at risk (OAR) were compared with literature maximum dose for patients with grade >2 toxicities, which were retrospectively assessed according to CTCAE v3.0. Results: Three patients in their fifties with stage II (n51) or III (n52) carcinoma of Bartholin’s gland were treated with a HDR 192Ir boost of 24 to 30 Gy divided in 5 or 6 fractions in complement to EBRT for 40-45 Gy in 1.8-2.0 Gy/fraction. There were one undifferienciated adenocarcinoma, one adenoid cystic carcinoma and one adenosquamous carcinoma. Two patients received postoperative irradiation for positive surgical margins or gross residual tumor and one patient was treated by radical chemoradiotherapy for locally advanced disease with anal involvement, in an attempt to avoid extensive surgery. All patients achieved a complete response. OS and DFS were both 100% at last followup (range: 55-68 months). Cumulative EQD2 doses to the tumor ranges from 72.3 to 77.5 Gy10 and average V100 was 98.8%. Acute toxicities observed were grade 3 vaginal mucositis (n52), grade 2 rectal mucositis (n51) and grade 2 urethral burning (n51). For late toxicities, 1 patient experienced grade 3 rectal bleeding and at analysis, no direct correlation was observed with its dose-volume values for rectum, as its RD2cc that was 69.3 Gy3. Another woman had grade 2 vaginal stenosis and 1 patient suffered from vaginal necrosis, with grade 3 pain, and she was treated with hyperbaric oxygen therapy. Conclusions: Use of HDR-ISBT in management of Bartholin’s gland carcinoma results in excellent long-term OS and DFS at a cost of possible
Abstracts / Brachytherapy 9 (2010) S23eS102
all patients were alive, and no local failures had occurred. Acute toxicities were mild. One grade >3 late event occurred, consisting of meningitis requiring hospitalization.
capability to shape the device to the needed dimensions intraoperatively may be an important advantage over prefabricated dural plaques. A highdose-rate dural boost may also provide dosimetric advantages when planning postoperative external beam radiation, particularly in patients who have previously been irradiated and the spinal cord tolerance is a significant concern. Further work will be necessary to substantiate whether these advantages will result in improved patient outcomes.
GYNECOLOGICAL POSTERS ThursdayeSaturday PO17
Conclusions: Treatment of HGG with the MammoSiteÒ and ConturaÔ devices is technically feasible. Though our initial clinical experience is encouraging, the safety and efficacy of these devices need to be tested in a larger cohort.
PO16 A Novel Application of 32P for High-Dose-Rate Brachytherapy of the Dura During Decompressive Spine Radiosurgery Yoshiya Yamada, M.D.1, Marco Zaider, Ph.D.2, Thomas Golembeski, M.S.3, Lawrence Dauer, Ph.D.2, Mark H. Bilsky, M.D.4 1Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY; 2 Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY; 3IBA Radioisotopes, Inc., Pleasanton, CA; 4Neurosurgery, Memorial Sloan-Kettering Cancer Center, New York, NY. Purpose: The dura is often contaminated with tumor cells in the setting of epidural extension of tumor, even after excellent surgical decompression of epidural disease. Despite the inherent dosimetric benefits of brachytherapy, traditional brachytherapy sources have not been used in regular practice to irradiate the dura. This may be due to excessive dose to the spinal cord or technical concerns which make it impractical. Phosphorus 32 (32P), a beta emitting isotope, was imbedded into a thin flexible soft plastic film in order to deliver high dose extremely short range radiation to the dura. The device has FDA clearance. Materials and Methods: The P32 film is approximately 0.35 mm thick and can deliver a dose of approximately 1 Gy per minute at the surface. After surgical decompression of epidural tumor, a non radioactive blank is cut to the desired shape and size. The blank is overlaid on the actual radioactive film in a water bath. The actual film is then cut to same shape and size, using the blank as a guide. The radioactive film is then carefully placed on the dural surface and left in place until the desired dose is delivered. When there is at least 3 mm of cerebral spinal fluid, a dose of 10 Gy to the dura will deliver less than 1 Gy to the surface of the underlying spinal cord. Results: Two patients have undergone intraoperative 32P dural brachytherapy. In each case, the patient had epidural cord compression requiring surgical decompression and had previously been irradiated at the site. A dose of 10 Gy was prescribed to the surface of the dura. Postoperative image-guided radiotherapy was delivered, taking into account the dose given to the dura. Because of the intraoperative brachytherapy boost, aggressive dosing near the spinal cord during external beam radiation treatment planning was not necessary, improving PTV coverage of the remainder of the volume by 10-20%. No post operative complications have been encountered. The followup is less than 2 months for both patients. Conclusions: Although the experience with the use of a 32P film for dural brachytherapy is very preliminary, it appears to be safe. The flexibility and
A Comparison of Dose Distribution from Two Different Intracavitary Brachytherapy Applicator Systems in Cervical Carcinoma Bishan Basu, M.D., Bikramjit Chakraborti, M.D., Suman Ghorai, M.D., Koushik Ghosh, M.Sc. Radiotherapy, Medical College Hospital, Kolkata, West Bengal, India. Purpose: Brachytherapy is an integral component of curative radiation therapy for the treatment of cervical carcinoma. Although intracavitary brachytherapy (ICBT) is the commonly performed procedure, during ICBT, the choice of applicator system (e.g., Fletcher-Suit, Manchesterstyle, Ring applicator, etc.,) is somewhat arbitrary. But, we thought that applicator geometry may play an important role in dose distribution. And, it may be possible to increase the therapeutic ratio (by selectively sparing the organs-at-risk eg. urinary bladder and rectum) by using one applicator over another. Materials and Methods: Patients suffering from locally advanced cervical carcinoma (unoperated) with ECOG Performance Status 0 or 1 without any other significant co-morbid conditions were enrolled for the study between July 2007 and December 2008. Patients who had contraindications to ICBT were excluded. 22 patients were selected. After completion of EBRT to the whole pelvis, patients underwent intracavitary brachytherapy with tandem and ovoid applicators. Two different types of CT-compatible applicators were used: Manchester-style and Fletcher-style applicators (Varian Medical Systems, Inc., Palo Alto, CA). The purpose was to compare the dose distribution obtained when two different applicators were applied to the same patient. So, in a given patient, if on the first insertion, Manchester-style applicator was used, Fletcher-style applicator was used on the next occasion and vice versa. The sequence of applicator was decided randomly (coin method). Based on the CT scan image of the whole pelvis in the treatment position with the applicator in place, dose was prescribed to Point A (Point H, according to ABS). To maintain comparability, for all insertions, a dose of 8 Gy was prescribed to the leftsided Point A. After adequate optimization the bladder and rectum doses (at ICRU point, 0.1cc, 1.0cc and 2cc volumes) were noted. Also the 100% isodose curve characteristics (maximum height, width & thickness of the 100% isodose curve, the 100% isodose volume as well as the width & thickness of the 100% isodose curve at the level of Point A) were noted. All data were analyzed using appropriate statistical test, i.e., Paired t test. Results: Regarding the 100% isodose characteristics, the 100% isodose volume and the maximum width of the 100% isodose curve were significantly greater (P value !.0001 in both occasions) when Manchester-style applicator was used. However, the dose received by 0.1 cc, 1.0 cc and 2.0 cc of the urinary bladder were also significantly greater (P value !0.0001) with the Manchester-style applicator. No significant difference was found in the rectal doses. Conclusions: The larger 100% isodose volume as well as the greater width of the 100% isodose curve achieved with the use of Manchester-style applicator can be helpful in circumstances where the disease is bulky. However this must be balanced against the increased dose received by the urinary bladder when the same applicator is used. This data must be correlated clinically before coming to any final decision. For clinical correlation, we are collecting relevant data from patients where the Manchester-style applicator was used and comparing them with data received from patients where the Fletcher-style applicator was used. After
Abstracts / Brachytherapy 9 (2010) S23eS102 detailed evaluation and statistical analysis of those data, we may reach a more confident conclusion. PO18 The Impact of Bladder Volume Variations on the Highest Bladder Dose Point Location During HDR Brachytherapy for Cervix Cancer Francois Bachand, M.D., Christina Aquino-Parsons, M.D., Rustom Dubash, M.S., Conrad Yuen, M.Sc., Peter Lim, M.D. Radiation Oncology, Vancouver Cancer Center, BC Cancer Agency, Vancouver, BC, Canada. Purpose: Intracavitary brachytherapy is an essential component of cervical cancer treatment. This treatment can result in a high dose to the bladder wall leading to radiation cystitis. Variations in bladder volume can result in changes in the high dose region of the bladder. We hypothesized that the location of the bladder high dose region varies in both location and dose with variations in bladder volume. Materials and Methods: A retrospective analysis of all HDR brachytherapy planning CT scans was performed in our center. Patients whose multiple scans demonstrated a considerable difference in bladder volume were selected for this analysis. A tandem and ring applicator was used for all implants. All patients were re-planned with standard loading, delivering 600 cGy at Point A. The location (coordinates and quadrants) and the intensity of the maximum bladder dose were compared between the small and large bladder volume scans using the paired t-test. The dose at the maximum bladder dose point defined in the small bladder group was assessed in the larger bladder scans. Results: 10 patients met the inclusion criteria with a mean difference of 191 cc in bladder volume. Mean bladder volume for the small bladder group was 141 cc vs 332 cc for the large bladder group (p ! 0.001). The mean bladder maximum dose point was 798 vs 1102 cGy for the small and large bladder groups respectively (p 5 0.028). The location of the maximum dose point changed quadrants in 7/10 patients. This translation was not demonstrated by the coordinate variation, Y 0.56cm (p 5 0.219) and X 0.24cm (p 5 0.381). The location and the dose of the hotspot did not change in the two patients with the smallest bladder volume difference. However, when the bladder volume difference was greater, the maximum bladder dose point identified in the small bladder group received less dose when the bladder was large (mean difference of 155 cGy, p 5 0.081). Conclusions: The location of the maximum dose point on the posterior wall of the bladder changes with bladder volume variation. With a larger bladder volume, the dose at the maximum dose point increases, but the dose at the maximum bladder dose point identified on the small bladder scans decreases. We hypothesize that bladder filling variations between implants, resulting in changes in the location of the high dose in the bladder, will lead to a decrease in radiation cystitis. We plan to look at this prospectively. PO19 Retrospective Analysis of Toxicity from Vaginal Cuff Brachytherapy Bruce Libby, Ph.D.1, Neil Sen, B.S.2, Bernard F. Schneider, Ph.D., M.D.1 1 Radiation Oncology, University of Virginia, Charlottesville, VA; 2School of Medicine, University of Virginia, Charlottesville, VA. Purpose: In order to determine both the efficacy and toxicities associated with post operative vaginal cuff brachytherapy, patient’s medical records were analyzed to determine rates of complications as well as recurrence rates. Materials and Methods: Medical records of 207 patients who received vaginal cuff brachytherapy at the University of Virginia were examined to compile the rates of radiation induced toxicities. Custom made clear acrylic cylinders of 2.3, 2.6, 3, 3.5, and 4 cm diameter were used, with the cylinder visually confirmed to be centered along the scar. Standard plans for each cylinder size were used, with a treatment length of 4 cm and the dose prescribed to 0.5 cm from the wall of the cylinder. The prescription was 7 Gy/fraction for 3 fractions, delivered 1 week apart. Vaginal cuff brachytherapy was the only radiation treatment used. Data were obtained immediately following the completion of brachytherapy, and at 6,12, 24, and >48 months post treatment.
S87
Results: Of the 207 patients, 144 (69.6%) experienced no radiation induced toxicities at any time. Of the patients who experienced toxicities, vaginitis/ discharge (10.6%) and vaginal stenosis/agglutination (9.7%) were the most prevalent, and most occurred soon after the completion of treatment. Eight patients experienced recurrence of the cancer: 1 patient (0.5%) experienced vaginal vault recurrence, 6 patients (2.9%) had abdominal or pelvic recurrence, and 1 patient (0.5%) had a distant metastasis. Conclusions: A retrospective analysis of adjuvant vaginal cuff brachytherapy shows that the treatment does not result in significant toxicities, and appears to be highly effective in preventing vaginal cuff recurrences following surgery for endometrial cancer.
PO20 High-Dose-Rate Interstitial Brachytherapy in the Management of Carcinoma of The Bartholin Gland: A Single Institution Experience with Long-Term Followup Isabelle Thibault, M.D., Marie-Claude Lavallee, M.Sc., Janelle Morrier, M.Sc., Eric Vigneault, M.D., M.Sc. Radiation Oncology, Centre Hospitalier Universitaire de Que´bec (CHUQ) - L’Hoˆtel-Dieu de Que´bec, Quebec, QC, Canada. Purpose: Carcinoma of the Bartholin gland is a rare malignancy considered by some as part of the vulvar cancers and by others as a distinct entity. Traditional therapeutic approach includes surgery but treatment algorithm including other modalities hasn’t been well defined. The purpose of this study is to assess the role, efficacy and toxicities of high-dose-rate (HDR) interstitial brachytherapy (ISBT) in the management of Bartholin’s gland cancer at L’Hoˆtel-Dieu de Que´bec. Materials and Methods: Between 2001 and 2009, three patients received HDR-ISBT for carcinoma of Bartholin’s gland and were retrospectively reviewed. The implantation procedure consisting of catheter insertion under fluoroscopic guidance through a Syed-Neblett template was performed under general anesthesia. After the procedure, a CT scan was done and dosimetry optimization was performed using inverse planning simulated annealing (IPSA) algorithm. The first treatment was delivered the same day using a HDR remote afterloading system and subsequent fractions were given twice a day. For each woman, tumor and treatment characteristics as well as reasons for ISBT were recorded. RECIST criteria were used to evaluate patient’s response to therapy. Overall survival (OS) and disease-free survival (DFS) were analyzed. Dosevolume histograms (DVH) were generated and doses were converted to equivalent dose in 2-Gy (EQD2). Total EQD2 doses of ISBT and external beam radiation therapy (EBRT) were calculated, with a/b ratio of 10 for tumor and of 3 for normal tissues. DVH parameters for organs at risk (OAR) were compared with literature maximum dose for patients with grade >2 toxicities, which were retrospectively assessed according to CTCAE v3.0. Results: Three patients in their fifties with stage II (n51) or III (n52) carcinoma of Bartholin’s gland were treated with a HDR 192Ir boost of 24 to 30 Gy divided in 5 or 6 fractions in complement to EBRT for 40-45 Gy in 1.8-2.0 Gy/fraction. There were one undifferienciated adenocarcinoma, one adenoid cystic carcinoma and one adenosquamous carcinoma. Two patients received postoperative irradiation for positive surgical margins or gross residual tumor and one patient was treated by radical chemoradiotherapy for locally advanced disease with anal involvement, in an attempt to avoid extensive surgery. All patients achieved a complete response. OS and DFS were both 100% at last followup (range: 55-68 months). Cumulative EQD2 doses to the tumor ranges from 72.3 to 77.5 Gy10 and average V100 was 98.8%. Acute toxicities observed were grade 3 vaginal mucositis (n52), grade 2 rectal mucositis (n51) and grade 2 urethral burning (n51). For late toxicities, 1 patient experienced grade 3 rectal bleeding and at analysis, no direct correlation was observed with its dose-volume values for rectum, as its RD2cc that was 69.3 Gy3. Another woman had grade 2 vaginal stenosis and 1 patient suffered from vaginal necrosis, with grade 3 pain, and she was treated with hyperbaric oxygen therapy. Conclusions: Use of HDR-ISBT in management of Bartholin’s gland carcinoma results in excellent long-term OS and DFS at a cost of possible