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Integration of CT-planned Interstitial Brachytherapy Boost in Advanced Gynecologic Malignancies
Poster Viewing Abstracts S459
Volume 84 Number 3S Supplement 2012
2638 MRI Guided High-dose-rate Vaginal Interstitial Brachytherapy for Locally Recurrent Endometrial Cancers N.G. Patil, G. Hajdok, K. Surry, G. McBrayne, A. Sugimoto, M. Prefontaine, L. Derrah, T. Murray, A. Lum, and D. D’Souza; London Regional Cancer Program, London, ON, Canada Purpose/Objective(s): To develop a novel method of using MR-guided High Dose Rate (HDR) vaginal interstitial brachytherapy (VIBT) using a vaginal cylinder at the time of pre-treatment MR Simulation (MR-SIM). Materials/Methods: MR imaging of stainless steel interstitial applicators in situ is difficult due to susceptibility artifacts, which can mask the location of applicator channels within a given needle, as well as compromise visibility of tumor and critical structures. Biopsy proven patients due to undergo VIBT have a MR-SIM a week before date of implant. In order to overcome the above challenges, a MR compatible vaginal cylinder is inserted at the time of MR-SIM. The cylinder is of the same dimensions as that of the central cylinder of the interstitial set. Each patient undergoes VIBT under general anesthesia in lithotomy position as a boost or as a primary treatment in select patients who have had previous radiation therapy. Post implant CT images are obtained for image registration and treatment planning. Axial T2 weighted images are fused with CT and used for contouring target and organ at risk volumes, using the vaginal cylinder as a fiducial. Results: Six cases have been implanted using this approach. The softtissue definition of the tumor volume is far superior compared to our previous experience with CT alone planning, where a cylindrical PTV is used to take into account the clinical assessment. The fused MR images are of particular help to define the cranial and caudal extent of the tumor. We are able to sculpt the dose, reducing the overall treatment volume with an expected reduction in acute and late toxicities. Conclusions: This unique approach of inserting a vaginal cylinder at the time of MR-SIM is feasible and well tolerated. MR images are good for target and OAR delineation without the need to transport the patient to a MR unit after interstitial application. With MR resources being limited in many radiation oncology departments, use of pre-implant MR provides valuable information that guides the treatment planning and quality of VIBT. All patients with upper vaginal/parametrial routinely undergo preoperative MR with a cylinder in situ now at our institution. While preliminary data is encouraging, longer follow-up is necessary before making recommendations. Author Disclosure: N.G. Patil: None. G. Hajdok: None. K. Surry: None. G. McBrayne: None. A. Sugimoto: None. M. Prefontaine: None. L. Derrah: None. T. Murray: None. A. Lum: None. D. D’Souza: None.
Purpose/Objective(s): To assess dosimetric and clinical outcomes in a series of patients receiving CT-guided high dose rate (HDR) gynecologic interstitial brachytherapy (IBT) boost. Materials/Methods: Sixty-three patients without previous radiation received high dose rate IBT at a single institution between August 2004 and February 2012. Patients included had gynecologic sites of tumor involvement. Thirty-three patients were treated in a setting of disease recurrence after previous surgery chemotherapy. The mean external beam radiation therapy (EBRT) dose was 45.4 Gy (range: 30 to 50.4 Gy). 28 (44%) patients received concurrent chemotherapy. A CT scan was performed after each implant with the applicators in place. Manual optimization of planning was performed to provide coverage to the target area while minimizing dose to organs at risk. A mean IBT dose of 18.4 Gy (range 12-24 Gy) was delivered over 2-4 HDR fractions, with a minimum interval of 6 hours between fractions. Dose Volume Histograms (DVHs) were computed for the organs at risk (OAR): bladder, rectum, sigmoid and small bowel. To allow quantitative comparison of doses to organs at risk, the dose to the 2.0cm3 volume (D2cc) was determined from the DVH. Cumulative biologically equivalent doses to the OARs were calculated by combining contributions from EBRT and IBT. To facilitate comparison with published values, total doses were normalized to 2 Gy per fraction equivalent doses (EQD2). Results: The mean number of catheters inserted was 12 (SD 3), covering a mean prescription volume (V100%) of 85.6 cc (SD 38.5 cc). The mean cumulative EQD2 to tumor was 61.8 20.7 Gy. The mean conformity index of the brachytherapy for the defined target volume was 0.628 0.107. The mean cumulative EQD2 to D2cc of bladder and rectum, respectively, was 51.8 23.0 Gy and 59.4 15.2 Gy. At a mean follow-up of 27.0 months (range 0-86.4 months), complete response was seen in 39 patients, and partial response in 8 patients. One patient had noted progression at initial follow-up, and response data was not available for 15 patients. 5 patients had recognized Grade 3 acute toxicity including radiation dermatitis (2), diarrhea (1) and local infection (2). There were 14 recognized Grade 3/4 late toxicity events, primary GI-related. Nineteen (30.2%) patients were identified to have tumor recurrence; including 9 local, 11 regional and 9 distant recurrences. The median time to recurrence was 31.0 months. The median overall survival estimate after interstitial implant was 34.9 months. Conclusions: IBT boost represents an effective and safe modality for providing conformal gross tumor doses to gynecologic sites of advanced malignancy with tumor geometry or anatomy that may not otherwise be feasible for EBRT or intracavitary brachytherapy boost. Author Disclosure: E.M. Wiebe: None. K. Surry: None. N. Patil: None. S. Aulakh: None. F. Whiston: None. L. Stitt: None. D. D’Souza: None.
2640 2639 Integration of CT-planned Interstitial Brachytherapy Boost in Advanced Gynecologic Malignancies E.M. Wiebe,1 K. Surry,2 N. Patil,2 S. Aulakh,2 F. Whiston,2 L. Stitt,3 and D. D’Souza2; 1Odette Cancer Centre, Toronto, ON, Canada, 2London Regional Cancer Program, London, ON, Canada, 3Western University, London, ON, Canada
Surveillance, Epidemiology, and End Results (SEER) Database Analysis of Verrucous Carcinoma of the Vulva S.B. Evans, A.P. Dosoretz, S. Damast, and J.B. Yu; Yale University, New Haven, CT Purpose/Objective(s): Verrucous carcinoma of the vulva is an unusual variant of squamous cell carcinoma, and it is believed to have a distinct clinical behavior. The case reports available suggest this entity is indolent
Poster Viewing Abstract 2638; Table Pt #
Age
Tumor size on MRI (CC/ML/AP) cm
1 2 3 4 5 6
78 55 76 79 51 75
5.5x2.0x2.2 5.7x4.6x5.0 2.0x1.2x1.1 4.2x3.0x2.8 2.2x2.2x1.9 2.6x1.9x3.0
External beam radiation therapy dose 45 Gy / 25#’s 45 Gy / 25#’s Previous 50.4 Gy / 26#’s 45 Gy / 25#’s 45 Gy / 25#’s 45 Gy / 25#’s
HDR dose (x3#’s) 6.5 6.5 7.0 6.5 6.5 6.5
Gy Gy Gy Gy Gy Gy
V100(%)
Bladder D2cc (Gy)
Rectum D2cc (Gy)
96.6 73.4 89.0 88.5 91.6 98.6
4.9 3.4 4.6 4.2 5.1 3.8
4.4 4.3 4.3 4.2 4.8 4.0
There were no adverse events with the cylinder insertion. In case #2, MRI indicated that a portion of the tumor was too superior to coverage with 20cm needles.
Volume 84 Number 3S Supplement 2012
2638 MRI Guided High-dose-rate Vaginal Interstitial Brachytherapy for Locally Recurrent Endometrial Cancers N.G. Patil, G. Hajdok, K. Surry, G. McBrayne, A. Sugimoto, M. Prefontaine, L. Derrah, T. Murray, A. Lum, and D. D’Souza; London Regional Cancer Program, London, ON, Canada Purpose/Objective(s): To develop a novel method of using MR-guided High Dose Rate (HDR) vaginal interstitial brachytherapy (VIBT) using a vaginal cylinder at the time of pre-treatment MR Simulation (MR-SIM). Materials/Methods: MR imaging of stainless steel interstitial applicators in situ is difficult due to susceptibility artifacts, which can mask the location of applicator channels within a given needle, as well as compromise visibility of tumor and critical structures. Biopsy proven patients due to undergo VIBT have a MR-SIM a week before date of implant. In order to overcome the above challenges, a MR compatible vaginal cylinder is inserted at the time of MR-SIM. The cylinder is of the same dimensions as that of the central cylinder of the interstitial set. Each patient undergoes VIBT under general anesthesia in lithotomy position as a boost or as a primary treatment in select patients who have had previous radiation therapy. Post implant CT images are obtained for image registration and treatment planning. Axial T2 weighted images are fused with CT and used for contouring target and organ at risk volumes, using the vaginal cylinder as a fiducial. Results: Six cases have been implanted using this approach. The softtissue definition of the tumor volume is far superior compared to our previous experience with CT alone planning, where a cylindrical PTV is used to take into account the clinical assessment. The fused MR images are of particular help to define the cranial and caudal extent of the tumor. We are able to sculpt the dose, reducing the overall treatment volume with an expected reduction in acute and late toxicities. Conclusions: This unique approach of inserting a vaginal cylinder at the time of MR-SIM is feasible and well tolerated. MR images are good for target and OAR delineation without the need to transport the patient to a MR unit after interstitial application. With MR resources being limited in many radiation oncology departments, use of pre-implant MR provides valuable information that guides the treatment planning and quality of VIBT. All patients with upper vaginal/parametrial routinely undergo preoperative MR with a cylinder in situ now at our institution. While preliminary data is encouraging, longer follow-up is necessary before making recommendations. Author Disclosure: N.G. Patil: None. G. Hajdok: None. K. Surry: None. G. McBrayne: None. A. Sugimoto: None. M. Prefontaine: None. L. Derrah: None. T. Murray: None. A. Lum: None. D. D’Souza: None.
Purpose/Objective(s): To assess dosimetric and clinical outcomes in a series of patients receiving CT-guided high dose rate (HDR) gynecologic interstitial brachytherapy (IBT) boost. Materials/Methods: Sixty-three patients without previous radiation received high dose rate IBT at a single institution between August 2004 and February 2012. Patients included had gynecologic sites of tumor involvement. Thirty-three patients were treated in a setting of disease recurrence after previous surgery chemotherapy. The mean external beam radiation therapy (EBRT) dose was 45.4 Gy (range: 30 to 50.4 Gy). 28 (44%) patients received concurrent chemotherapy. A CT scan was performed after each implant with the applicators in place. Manual optimization of planning was performed to provide coverage to the target area while minimizing dose to organs at risk. A mean IBT dose of 18.4 Gy (range 12-24 Gy) was delivered over 2-4 HDR fractions, with a minimum interval of 6 hours between fractions. Dose Volume Histograms (DVHs) were computed for the organs at risk (OAR): bladder, rectum, sigmoid and small bowel. To allow quantitative comparison of doses to organs at risk, the dose to the 2.0cm3 volume (D2cc) was determined from the DVH. Cumulative biologically equivalent doses to the OARs were calculated by combining contributions from EBRT and IBT. To facilitate comparison with published values, total doses were normalized to 2 Gy per fraction equivalent doses (EQD2). Results: The mean number of catheters inserted was 12 (SD 3), covering a mean prescription volume (V100%) of 85.6 cc (SD 38.5 cc). The mean cumulative EQD2 to tumor was 61.8 20.7 Gy. The mean conformity index of the brachytherapy for the defined target volume was 0.628 0.107. The mean cumulative EQD2 to D2cc of bladder and rectum, respectively, was 51.8 23.0 Gy and 59.4 15.2 Gy. At a mean follow-up of 27.0 months (range 0-86.4 months), complete response was seen in 39 patients, and partial response in 8 patients. One patient had noted progression at initial follow-up, and response data was not available for 15 patients. 5 patients had recognized Grade 3 acute toxicity including radiation dermatitis (2), diarrhea (1) and local infection (2). There were 14 recognized Grade 3/4 late toxicity events, primary GI-related. Nineteen (30.2%) patients were identified to have tumor recurrence; including 9 local, 11 regional and 9 distant recurrences. The median time to recurrence was 31.0 months. The median overall survival estimate after interstitial implant was 34.9 months. Conclusions: IBT boost represents an effective and safe modality for providing conformal gross tumor doses to gynecologic sites of advanced malignancy with tumor geometry or anatomy that may not otherwise be feasible for EBRT or intracavitary brachytherapy boost. Author Disclosure: E.M. Wiebe: None. K. Surry: None. N. Patil: None. S. Aulakh: None. F. Whiston: None. L. Stitt: None. D. D’Souza: None.
2640 2639 Integration of CT-planned Interstitial Brachytherapy Boost in Advanced Gynecologic Malignancies E.M. Wiebe,1 K. Surry,2 N. Patil,2 S. Aulakh,2 F. Whiston,2 L. Stitt,3 and D. D’Souza2; 1Odette Cancer Centre, Toronto, ON, Canada, 2London Regional Cancer Program, London, ON, Canada, 3Western University, London, ON, Canada
Surveillance, Epidemiology, and End Results (SEER) Database Analysis of Verrucous Carcinoma of the Vulva S.B. Evans, A.P. Dosoretz, S. Damast, and J.B. Yu; Yale University, New Haven, CT Purpose/Objective(s): Verrucous carcinoma of the vulva is an unusual variant of squamous cell carcinoma, and it is believed to have a distinct clinical behavior. The case reports available suggest this entity is indolent
Poster Viewing Abstract 2638; Table Pt #
Age
Tumor size on MRI (CC/ML/AP) cm
1 2 3 4 5 6
78 55 76 79 51 75
5.5x2.0x2.2 5.7x4.6x5.0 2.0x1.2x1.1 4.2x3.0x2.8 2.2x2.2x1.9 2.6x1.9x3.0
External beam radiation therapy dose 45 Gy / 25#’s 45 Gy / 25#’s Previous 50.4 Gy / 26#’s 45 Gy / 25#’s 45 Gy / 25#’s 45 Gy / 25#’s
HDR dose (x3#’s) 6.5 6.5 7.0 6.5 6.5 6.5
Gy Gy Gy Gy Gy Gy
V100(%)
Bladder D2cc (Gy)
Rectum D2cc (Gy)
96.6 73.4 89.0 88.5 91.6 98.6
4.9 3.4 4.6 4.2 5.1 3.8
4.4 4.3 4.3 4.2 4.8 4.0
There were no adverse events with the cylinder insertion. In case #2, MRI indicated that a portion of the tumor was too superior to coverage with 20cm needles.