- Email: [email protected]
Response to editorial by DR. Maruyama
Int J Radral;on O~CdOgJ~ Bid Phys, Vol. Printed in the U.S.A. All rights reserved.
27, PP.
0360.3016193 $6.00 + .oO Copyright G 1993 Pergamon Press Ltd.
1255-1256
??Correspondence
RESPONSE
TO EDITORIAL
RADIATION
BY DR. MARUYAMA
TO THE
INTACT
GROIN
To the Editor: The study of “Femoral Vessel Depth and the Impliby Koh et al. (3) is eloquent in its simplicity. Those authors’ review of scans from 50 patients with gynecologic cancer confirm that computed tomography is a simple and reproducible method for planning groin radiation. This technique was underused in Gynecologic Oncology Group (GQG) protocol #88 (8). While the GOG is convinced that there is a role for radiation therapy in carcinoma of the vulva (2) we were surprised by the results of this study. The report by Koh ef al. helped shed light upon why radiation therapy as a single modality to the intact groin was not successful. The GQG protocol recommended a treatment prescription for dose and depth, similar to that reported by Henderson et al. (I), that is 50 Gy calculated at 3 cm below the skin surface. Since publications of our report, Lee has updated the experience of the University of Florida (5). Approximately half of their patients received a portion of their therapy with 8- I4 MeV electrons. Petereit and colleagues from the University of Wisconsin (7) did not use electrons, but did use bolus material, while loading (6-MV photons anPerez et al. (6) used 2:1 anterior/posterior teriorly and l8-MV photons posteriorly) and/or 9-12 MeV electrons. Each of these groups calculated dose at 3-4 cm. Note that Lee’s report includes eight femoral neck fractures in 7 patients, even though many of their patients were male. These investigators compared boost techniques (photons and electrons), but could not confirm an increased risk of fracture associated with photons. They have discontinued the use of electron boost, however. Koh and co-workers document that virtually all currently available texts are incorrect in describing the guidelines for prescription depth for groin irradiation. The minimum depth is 3 cm with an average depth of 6.1 cm in this population. Their demonstration of a linear relationship between Quetelet index and depth may be useful in grouping patients and comparing published series, but this relationship should not substitute for exact target volume definition in each individual case. The GOG believes that tumor volume may also be a factor in the failure of our study. Two out of 5 of our patients who suffered groin relapse were treated only with photons. As Thomas points out (9) not all subclinical disease is microscopic disease. Like nodal depth, the volume of tumor in groin nodes may have been underestimated. The value of the information gained by node dissection should not be underestimated. The GOG protocol compared radiation therapy to the intact groin against groin dissection followed by directed radiation therapy for node-positive patients. As demonstrated by Homesley et nl. (2) radiation therapy is extremely effective in reducing the risk of groin failure in the node-positive postoperative groin. Approximately 75% of these patients with No_, clinical node status need no treatment to the groin and 5 to 10% of these patients will need more therapy than 5 Gy. Lanciano (4) points out in an editorial in last month’s journal that only one or two more failures in Petereit’s (7) non-randomized comparison of groin dissection versus groin radiation would have made the difference in groin failure statistically and clinically significant. If these four recent studies are combined, the failure rate in the radiated groin is 12/105 = I 1.5% (Lee 3/16; Perez 2/39; Petreit 2/23; GOG 5/27). Perhaps most distressing is the fact that virtually all patients who relapse in the groin die of their disease. Radiation therapy is an effective modality in vulvar cancer, and the GOG will continue to pursue studies that attempt to further define its role. Though GQG #88 was not a positive study in the usual sense, we
To the Editor; We are happy to read in the previous issue of the journal Dr. Maruyama agrees with the main message of our study, reemphasizing the fact that imaging allows the objective assessment of cervical tumor size and extent and, thus, the routine use of imaging may reduce examiner and institutional variations. This may facilitate the design of therapy and the assessment of outcome by independent reviewers. Dr. Maruyama went one step further by predicting that the traditional staging system for cervical cancer will incorporate information provided by the imaging modalities to augment staging accuracy. Magnetic resonance imaging (MRI) has been in clinical use for approximately 10 years, but the great interest for this modality worldwide has increased in the last 5 years, as documented by the Medicine literature search (January 1989 to September 1993) which shows 82 published papers on cervical cancer. The prediction for MRI over computed tomography (CT) in the evaluation of cancer of the cervix stems from the fact that MRI soft tissue contrast resolution is far superior to that of CT making direct tumor visualization possible (3). Although surgical-pathologic assessment remains the gold standard, the evaluation of tumor size by MRI shows superb correlation to pathology with a correlation coefficient equaling or exceeding r = .95 (I, 2). Computed tomography does not provide the soft tissue contrast resolution that allows direct tumor visualization or separation between tumor and the adjacent cervical or uterine tissue. The direct multi-planar imaging of MRI is another advantage of this modality. In direct multiplanar imaging and the ability to assess tumor size, one should not forget endovaginal ultrasound. Endovaginal ultrasound can be used to directly visualize cervical cancer, but the small field of view and contrast resolution offered by ultrasound limit the evaluation of larger tumors and makes clear differentiation between tumor and adjacent parametria or the evaluation of cranial tumor extension difficult. Magnetic resonance studies, although ideally suited for the evaluation of cervical cancer are, however, expensive and the units are not widely available (there are, however, over 3,000 magnets in the United States, but they are generally concentrated in large cities). To obtain the full benefit of MRI, the education of radiologists needs to be improved, and oncologists have to be appraised of the potential that this modality offers. Furthermore, large longitudinal studies need to be undertaken to assess the outcome benefits offered by this imaging modality in the staging of cervical cancer.
cations for Groin Node Radiation”
HEDVIG HRICAK, M.D., PH.D. Urology and Radiation Oncology University of California-San Francisco Department of Radiology San Francisco, CA 94 143-0628
Burghardt, E.: Hofmann, H. M.: Ebner, F.: Haas, J.: Tamussino, K.: Justich, E. Magnetic resonance imaging in cervical cancer: A basis for objective classification. Gynecol. Oncol. 33:6 l-67; 1989. Hricak, H.: Hamm, B.: Semelka, R. C.: Cann, C. E.: Nauert, T.: Secaf, E.: Stern, J. L.: Wolf, K.-J. Carcinoma of the uterus: Use of gadopentetate dimeglumine in MR imaging. Radiology 18 I :95- 106; 1991. Kim, S. H.: Choi, B. I.: Han, J. K.: Kim, H. D.: Lee, H. P.: Kang, S. B.: Lee, J. Y.: Han, M. C. Preoperative staging of uterine cervical carcinoma: Comparison of CT and MRI in 99 patients. JCAT 17: 633-640; 1993.
Accepted
Reprint requests to: Frederick B. Stehman, M.D., Professor, Obstetrics and Gynecology, Indiana University Medical Center, 550 N. University, UH 2440, Indianapolis, IN 46202.
1255
for publication
4 October
1993.
27, PP.
0360.3016193 $6.00 + .oO Copyright G 1993 Pergamon Press Ltd.
1255-1256
??Correspondence
RESPONSE
TO EDITORIAL
RADIATION
BY DR. MARUYAMA
TO THE
INTACT
GROIN
To the Editor: The study of “Femoral Vessel Depth and the Impliby Koh et al. (3) is eloquent in its simplicity. Those authors’ review of scans from 50 patients with gynecologic cancer confirm that computed tomography is a simple and reproducible method for planning groin radiation. This technique was underused in Gynecologic Oncology Group (GQG) protocol #88 (8). While the GOG is convinced that there is a role for radiation therapy in carcinoma of the vulva (2) we were surprised by the results of this study. The report by Koh ef al. helped shed light upon why radiation therapy as a single modality to the intact groin was not successful. The GQG protocol recommended a treatment prescription for dose and depth, similar to that reported by Henderson et al. (I), that is 50 Gy calculated at 3 cm below the skin surface. Since publications of our report, Lee has updated the experience of the University of Florida (5). Approximately half of their patients received a portion of their therapy with 8- I4 MeV electrons. Petereit and colleagues from the University of Wisconsin (7) did not use electrons, but did use bolus material, while loading (6-MV photons anPerez et al. (6) used 2:1 anterior/posterior teriorly and l8-MV photons posteriorly) and/or 9-12 MeV electrons. Each of these groups calculated dose at 3-4 cm. Note that Lee’s report includes eight femoral neck fractures in 7 patients, even though many of their patients were male. These investigators compared boost techniques (photons and electrons), but could not confirm an increased risk of fracture associated with photons. They have discontinued the use of electron boost, however. Koh and co-workers document that virtually all currently available texts are incorrect in describing the guidelines for prescription depth for groin irradiation. The minimum depth is 3 cm with an average depth of 6.1 cm in this population. Their demonstration of a linear relationship between Quetelet index and depth may be useful in grouping patients and comparing published series, but this relationship should not substitute for exact target volume definition in each individual case. The GOG believes that tumor volume may also be a factor in the failure of our study. Two out of 5 of our patients who suffered groin relapse were treated only with photons. As Thomas points out (9) not all subclinical disease is microscopic disease. Like nodal depth, the volume of tumor in groin nodes may have been underestimated. The value of the information gained by node dissection should not be underestimated. The GOG protocol compared radiation therapy to the intact groin against groin dissection followed by directed radiation therapy for node-positive patients. As demonstrated by Homesley et nl. (2) radiation therapy is extremely effective in reducing the risk of groin failure in the node-positive postoperative groin. Approximately 75% of these patients with No_, clinical node status need no treatment to the groin and 5 to 10% of these patients will need more therapy than 5 Gy. Lanciano (4) points out in an editorial in last month’s journal that only one or two more failures in Petereit’s (7) non-randomized comparison of groin dissection versus groin radiation would have made the difference in groin failure statistically and clinically significant. If these four recent studies are combined, the failure rate in the radiated groin is 12/105 = I 1.5% (Lee 3/16; Perez 2/39; Petreit 2/23; GOG 5/27). Perhaps most distressing is the fact that virtually all patients who relapse in the groin die of their disease. Radiation therapy is an effective modality in vulvar cancer, and the GOG will continue to pursue studies that attempt to further define its role. Though GQG #88 was not a positive study in the usual sense, we
To the Editor; We are happy to read in the previous issue of the journal Dr. Maruyama agrees with the main message of our study, reemphasizing the fact that imaging allows the objective assessment of cervical tumor size and extent and, thus, the routine use of imaging may reduce examiner and institutional variations. This may facilitate the design of therapy and the assessment of outcome by independent reviewers. Dr. Maruyama went one step further by predicting that the traditional staging system for cervical cancer will incorporate information provided by the imaging modalities to augment staging accuracy. Magnetic resonance imaging (MRI) has been in clinical use for approximately 10 years, but the great interest for this modality worldwide has increased in the last 5 years, as documented by the Medicine literature search (January 1989 to September 1993) which shows 82 published papers on cervical cancer. The prediction for MRI over computed tomography (CT) in the evaluation of cancer of the cervix stems from the fact that MRI soft tissue contrast resolution is far superior to that of CT making direct tumor visualization possible (3). Although surgical-pathologic assessment remains the gold standard, the evaluation of tumor size by MRI shows superb correlation to pathology with a correlation coefficient equaling or exceeding r = .95 (I, 2). Computed tomography does not provide the soft tissue contrast resolution that allows direct tumor visualization or separation between tumor and the adjacent cervical or uterine tissue. The direct multi-planar imaging of MRI is another advantage of this modality. In direct multiplanar imaging and the ability to assess tumor size, one should not forget endovaginal ultrasound. Endovaginal ultrasound can be used to directly visualize cervical cancer, but the small field of view and contrast resolution offered by ultrasound limit the evaluation of larger tumors and makes clear differentiation between tumor and adjacent parametria or the evaluation of cranial tumor extension difficult. Magnetic resonance studies, although ideally suited for the evaluation of cervical cancer are, however, expensive and the units are not widely available (there are, however, over 3,000 magnets in the United States, but they are generally concentrated in large cities). To obtain the full benefit of MRI, the education of radiologists needs to be improved, and oncologists have to be appraised of the potential that this modality offers. Furthermore, large longitudinal studies need to be undertaken to assess the outcome benefits offered by this imaging modality in the staging of cervical cancer.
cations for Groin Node Radiation”
HEDVIG HRICAK, M.D., PH.D. Urology and Radiation Oncology University of California-San Francisco Department of Radiology San Francisco, CA 94 143-0628
Burghardt, E.: Hofmann, H. M.: Ebner, F.: Haas, J.: Tamussino, K.: Justich, E. Magnetic resonance imaging in cervical cancer: A basis for objective classification. Gynecol. Oncol. 33:6 l-67; 1989. Hricak, H.: Hamm, B.: Semelka, R. C.: Cann, C. E.: Nauert, T.: Secaf, E.: Stern, J. L.: Wolf, K.-J. Carcinoma of the uterus: Use of gadopentetate dimeglumine in MR imaging. Radiology 18 I :95- 106; 1991. Kim, S. H.: Choi, B. I.: Han, J. K.: Kim, H. D.: Lee, H. P.: Kang, S. B.: Lee, J. Y.: Han, M. C. Preoperative staging of uterine cervical carcinoma: Comparison of CT and MRI in 99 patients. JCAT 17: 633-640; 1993.
Accepted
Reprint requests to: Frederick B. Stehman, M.D., Professor, Obstetrics and Gynecology, Indiana University Medical Center, 550 N. University, UH 2440, Indianapolis, IN 46202.
1255
for publication
4 October
1993.