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High dose rate intracavitary brachytherapy of early and superficial carcinoma of the nasal vestibule as an alternative to low dose rate interstitial radiation therapy
Radiotherapy and Oncology, 27 (1993) 69-72 © 1993 Elsevier Scientific Publishers Ireland Ltd. All rights reserved. 0167-8140/93/$06.00
69
RADION01149
Technical Note
High dose rate intracavitary brachytherapy of early and superficial carcinoma of the nasal vestibule as an alternative to low dose rate interstitial radiation therapy Lucas A.M. Pop a, Johannes H.A.M. Kaanders a and Eduard C.M. Heinerman b alnstitute of Radiotherapy and bE.N.T. Department, University of Nijmegen, Nijmegen, The Netherlands (Received 20 October 1992; revision received 20 December 1992; accepted 4 January 1993)
Material and methods
Key words: Nasal vestibule; Brachytherapy; High dose rate; Mould
Summary A new technique of high dose rate intracavitary brachytherapy is introduced for treating patients with early and superficial squamous cell carcinoma of the nasal vestibule. This method is illustrated by a case report. A customized intranasul mould was fabricated in which afterloading catheters were placed. These catheters were loaded with a high activity 192Ir pointsource, using the HDR-microSelectron. In this way the patient was treated twice daily over 5 days without hospitalization. The indications for the use of this technique and the advantages in comparison with low dose rate interstitial irradiation are discussed.
Introduction
Brachytherapy plays an important role in the management of early squamous cell carcinomas of the nasal vestibule. Excellent results in terms of local control and late cosmesis are obtained with interstitial low dose rate either combined or not with external beam radiation therapy [2,6-10,12,13]. Local control with surgery is equally good [1,3,5,7]. In our opinion however, surgery should only be considered if a radical resection does not produce cosmetic defects in this highly visible region. To our knowledge brachytherapy in cancer of the nasal vestibule has only been performed with low dose rate (LDR) interstitial irradiation, with, in an exceptional case, the use of a surface mould and almost median dose rate [6]. The purpose of this communication is to report on a patient with an early and superficial squamous cell carcinoma of the nasal vestibule treated with high dose rate (HDR) intracavitary brachytherapy as an alternative to LDR interstitial radiation therapy.
In January 1991 a 55-year-old man presented himself with a small superficial lesion on the medial wall of the left nasal vestibule. On physical examination by the radiotherapist and ENT surgeon the tumor measured 1.5 cm in largest dimension with a thickness of 2-3 mm. There was neither extension to skin, lip, nor cartilage or bone. There were no palpable lymph nodes in the neck. A biopsy of the tumor revealed a moderately differentiated squamous cell carcinoma. Because there was an absolute (cardiac) contraindication for general anaesthesia, we decided to treat the patient by intracavitary HDR irradiation with the use of the HDR-microSelectron. In cooperation with the department of Removable and Maxillo-facial Prosthodontics a mould of the nasal cavity was constructed. Using an alginate paste an impression of the left nasal vestibule and the tumor was obtained, together with the right nasal cavity and upper lip. The latter in order to assure placement of the mould into a fixated position. The alginate model was duplicated in methyl metacrylate, in which two parallel plastic afterloading catheters were placed at a distance of 9-10 mm from each other. It was ensured that the catheters were positioned in the same plane, 2 mm underneath and parallel to the medial surface of the acrylic mould at the left side (Fig. 1). A reconstruction of the catheters in the mould was made and a pre-planned dose distribution was calculated with the NPS computer program. In each catheter an active length of 3.5 cm was chosen in order to deliver an adequate dose to the target volume including the tumor with a 0.5-cm margin. To encompass the whole tumor thickness in the transversal direction the isodose level at a 3-mm distance to the medial outer surface of the mould in the midplane was taken as the reference isodose. This is at a 5-mm distance to the plane of the sources in the same direction. The prescribed dose at the refer-
Correspondence to: L.A.M. Pop, Institute of Radiotherapy, University of Nijmegen, Nijmegen, The Netherlands.
70
Through ( 0,
O.
source 3 69Cl
3S~
03
Ir-leZ
Scale. 4ool Dose : coy Coord syste~ Interactive
A
AZ~ R m d l o ~ b ~ p ~
-y 70s -axis Thr°ugh ( o. o.
~
3sJ z35
o)
3 ~gc1 I r - l g 2 Scale 4001 Dose : cGy Coord system Interactive
/
up~ .9
Fig. 2. Dose distribution around the catheters. The isodose of 470 cGy is taken as the referenceisodose. A, Central plane, defined as the plane perpendicular to the midlines of the active part of each catheter (i.e., the transversal plane). The reference isodose of 470 cGy is located at 3 mm to the outer surface of the mould at the medial side and at 5 mm to the plane of the catheters. B, Coronal plane just between the two catheters. Fig. 1. Anterior (A) and lateral (B) view of the mould with the two parallelcatheters placed in the left side of the mould with a mutual distance of I cm. The catheters, located in the same plane, are best seen at the lateral view.
ence isodose was chosen to be 4.7 Gy, requiring a dwell time of 7.2 s for each position of the high activity pointsource (actual activity 3.69 Ci) of the HDR-microSelectron. There were, respectively seven source positions with a stepsize of 5 mm in each catheter. As shown in Fig. 2 the 4.7-Gy isodose encompassed the entire target volume in all planes, while the higher doses in the near vicinity of the sources are located within the tissue equivalent material of the mould. Subsequently, the mould was introduced in the patient's nasal cavity and fixed with adhesive tape. AP and lateral isocentric radiographs were taken and a reconstruction of the mould and nasal cavity was made. Calculation of the isodose profiles was performed in the coronal, sagittal and transversal planes. The position of the reference isodose as assumed in the predictive dosimetry and the dose homogeneity were checked in the different planes. With 4.7 Gy delivered at the reference isodose the actual doses applied in the tumor and the surrounding normal tissues were as precalculated. Based on the experience with low dose rate irradiation in which 60-65 Gy is given
at a dose rate of 40-60 cGy/h, a dose equivalent radiation scheme for fractionated high dose rate irradiation was calculated with the use of the incomplete repair model of Thames [11]. We choose a low dose rate irradiation scheme of 65 Gy at a dose rate of 50 cGy?h as reference for both local tumor control and maximal tolerated dose regarding normal tissues. We assumed an tx/B ratio of 10 Gy and a repair halftime of 0.5 h for the tumor tissue and 3 - 4 Gy and 1.5 h for the late-reacting normal tissues, such as cartilage and fibrous tissue. A HDR-fractionated irradiation scheme delivering ten fractions of 4.7 Gy, two fractions per day and with an interval of 8 h was calculated to be biologically equivalent to the low dose rate reference schedule as to tumor control probability. Regarding the normal tissues, an excess of 5-10% of the biological effect of the HDR irradiation scheme as compared to 65 Gy at a (low) dose rate of 50 cGy/h was accepted. Two fractions per day were delivered for 5 consecutive days, each first fraction at 09:00 h and the second at 17:00 h. After each fraction the mould was removed from the nasal cavity and the patient went home. The placement of the mould turned out to be easy, nontraumatic and painless. The position of the mould and thus the dose distribution was reproducible, as was verified by repeated X-ray films.
71
Follow-up results The treatment was tolerated very well. Only minor acute side-effects were observed. Two weeks after completion of radiotherapy there was a brisk redness of the mucosa of the nasal cavity with no complaints of pain. At the moment of this report, two years later, the patient is without complaints and without evidence of disease. There is a slight atrophy and dryness of the mucosa, with no late effects of the skin of the nose and the upper lip. There is no evidence of chondritis of the nasal septum.
Discussion Early squamous cell carcinoma of the nasal vestibule is a relatively rare disease. Primary treatment is historically based on surgery or external beam radiotherapy. During the last two decades, the use of low dose rate brachytherapy became increasingly important, with excellent results in terms of local control and cosmesis [2,6-10,12,13]. This report describes a new brachytherapeutic approach using fractionated high dose rate intracavitary irradiation, which turned out to be feasible. We believe that this technique using a mould and a HDR remote afterloading machine has several advantages over low dose rate interstitial irradiation. For implantation of needles for low dose rate interstitial irradiation (LDR-IRT) the patient has to be hospitalized and usually needs general anaesthesia. During the treatment time of the LDR-IRT, mostly 5 - 6 days, the patient must be isolated in a specially designed radioprotected room, which complicates nursing and visiting. This could be accompanied with psychological distress for the patient. Our technique is not invasive, painless and allows treatment on an out-patient basis. A stable and reproducible source position is guaranteed during the short time of each fraction of the HDR irradiation. The fixed, pre-planned geometry of the catheters makes forecast of dosimetry possible. If the pre-planned dose distribution in the target volume is not adequate, the catheters can be replaced. The dose homogeneity is improved with the use of this technique, while higher doses in the near vicinity of the sources are located within the tissue-equivalent material of the mould. Moreover, the dose distribution in relation to the tumor and the surrounding normal tissues can be verified before each
fraction and small deviations can be corrected with an optimization computerprogram. A technique which makes use of a mould and almost medium dose rate has been described by Haynes and Tapley [6]. It has some of the advantages of our technique, but the use of radium as a radioactive source is not recommended because of the undesirable radiation exposure of patient, physician and nurses. It also does not allow optimization of dose distribution. With low dose rate irradiation at a dose rate of 50 cGy/h and a total dose of 65 Gy as used in clinical practice, tumor control is excellent, while the late-reacting normal tissues are expected and proven to be maximally spared [2,6-10,12,13]. However, from a radio-biological point of view, a dose equivalent radiation scheme with regard to both local tumor control and normal tissue tolerance can be approached by delivering the HDR irradiation in ten fractions of 4.7 Gy, with a time interval between each fraction of at least 8 h [4,11]. It is not in the scope of this paper to further discuss dose rate effects and fractionation. So far, 2 years later, the patient has no evidence of disease and shows no significant late side-effects. However, follow up is still short and experience too limited to be conclusive about definite local control and late effects on normal tissues.
Conclusion We feel that this technique of high dose rate intracavitary brachytherapy is certainly worth considering in lieu of low dose rate interstitial irradiation for early lesions of the nasal vestibule. The use of a mould is a noninvasive procedure and yields a predictable and reproducible distribution of the radiation dose closely fitting the tumor volume, while the surrounding normal tissues are maximally spared by the rapid dose fall-off. However, for more extensive and infiltrating lesions we still prefer interstitial brachytherapy either alone or combined with external beam irradiation.
Acknowledgements The authors wish to thank M.E. van Leer, M.D. and J. van Lokven from the department of Removable and Maxillo-facial Prosthodontics for their cooperation in constructing the mould.
References 1 Boulos, E. External rhinoplasty approach for lesions of the nasal vestibule. Laryngoscope 94: 703-704, 1984. 2 Chassagne, D. and Wilson, F. Brachytherapy of carcinomas of the nasal vestibule. Int. J. Radiat. Oncol., Biol. Phys. 10: 761, 1984. 3 De Jong, J. M. A., Schalekamp, W. and Hordijk, G. J. Squamous cell carcinoma of the nasal vestibule. Clin. Otolaryngol. 6: 205-208, 1981. 4 Fowler, J.F. The radiobiology of brachytherapy. In: Brachytherapy HDR and LDR, pp. 121-137. Editors: A.A. Martinez, C.G. Orton and R.F. Mould. Nucletron Corporation, Columbia, 1990. 5 Goepfert, H., Guillamondequi, O. M., Jesse, R. H. and Lindberg, R.D. Squamous cell carcinoma of the nasal vestibule. Arch. Otolaryngol. 100: 8-10, 1974.
6 Haynes, W. D. and Tapley, N. Radiation treatment of carcinoma of the nasal vestibule. Am. J. Roentgenol. 120: 595-602, 1974. 7 Kagan, R. A., Nussbaum, H., Rao, A., Chan, P., Gilbert, H., Hintz B., Ryoo, M., Miles, J. and Rice, D. The management of carcinoma of the nasal vestibule. Head Neck Surg. 4: 125-128, 1981. 8 Levendag, P.C. and Pomp, J. Radiation therapy of squamous cell carcinoma of the nasal vestibule. Int. J. Radiat. Oncol., Biol. Phys. 19: 1363-1367, 1990. 9 Mazeron, J. J., Chassagne, D., Crook, J., Bachelot, F., Brochet, F., Brune, D., Brunin, F., Bunesco, N., Daly, N., Danczak, S., Dubois, J. B., Grangean, M., Hoffstetter, S., Koechlin, M., Huart, J., Labib, A., Madelain, M., Maylin, C., ReynaudBouggnoux, A., Rozan, R. and Serpantie, P. Radiation therapy
72 of carcinomas of the skin of nose and nasal vestibule; A report of 1676 cases by the Groupe Europcen de Curietherapie. Radiother. Oncol. 13: 165-173, 1989. 10 Mendenhall, N. P., Parsons, J. T., Cassisi, N. J. and Million, R. R. Carcinoma of the nasal vestibule. Int. J. Radiat. Oncol., Biol. Phys. 10: 627-637, 1984. 11 Thames, H.D. An incomplete repair model for survival after
12 13
fractionated and continuous irradiation. Int. J. Radiat. Biol. 47: 319-339, 1985. Wang, C.C. Treatment of carcinoma of the nasal vestibule by irradiation. Cancer 38: 100-106, 1976. Wong, C. S. and Cummings, B.J. The place of radiation therapy in the treatment of squamous cell carcinoma of the nasal vestibule - - a review. Acta Oncol. 27: 203-208, 1988.
69
RADION01149
Technical Note
High dose rate intracavitary brachytherapy of early and superficial carcinoma of the nasal vestibule as an alternative to low dose rate interstitial radiation therapy Lucas A.M. Pop a, Johannes H.A.M. Kaanders a and Eduard C.M. Heinerman b alnstitute of Radiotherapy and bE.N.T. Department, University of Nijmegen, Nijmegen, The Netherlands (Received 20 October 1992; revision received 20 December 1992; accepted 4 January 1993)
Material and methods
Key words: Nasal vestibule; Brachytherapy; High dose rate; Mould
Summary A new technique of high dose rate intracavitary brachytherapy is introduced for treating patients with early and superficial squamous cell carcinoma of the nasal vestibule. This method is illustrated by a case report. A customized intranasul mould was fabricated in which afterloading catheters were placed. These catheters were loaded with a high activity 192Ir pointsource, using the HDR-microSelectron. In this way the patient was treated twice daily over 5 days without hospitalization. The indications for the use of this technique and the advantages in comparison with low dose rate interstitial irradiation are discussed.
Introduction
Brachytherapy plays an important role in the management of early squamous cell carcinomas of the nasal vestibule. Excellent results in terms of local control and late cosmesis are obtained with interstitial low dose rate either combined or not with external beam radiation therapy [2,6-10,12,13]. Local control with surgery is equally good [1,3,5,7]. In our opinion however, surgery should only be considered if a radical resection does not produce cosmetic defects in this highly visible region. To our knowledge brachytherapy in cancer of the nasal vestibule has only been performed with low dose rate (LDR) interstitial irradiation, with, in an exceptional case, the use of a surface mould and almost median dose rate [6]. The purpose of this communication is to report on a patient with an early and superficial squamous cell carcinoma of the nasal vestibule treated with high dose rate (HDR) intracavitary brachytherapy as an alternative to LDR interstitial radiation therapy.
In January 1991 a 55-year-old man presented himself with a small superficial lesion on the medial wall of the left nasal vestibule. On physical examination by the radiotherapist and ENT surgeon the tumor measured 1.5 cm in largest dimension with a thickness of 2-3 mm. There was neither extension to skin, lip, nor cartilage or bone. There were no palpable lymph nodes in the neck. A biopsy of the tumor revealed a moderately differentiated squamous cell carcinoma. Because there was an absolute (cardiac) contraindication for general anaesthesia, we decided to treat the patient by intracavitary HDR irradiation with the use of the HDR-microSelectron. In cooperation with the department of Removable and Maxillo-facial Prosthodontics a mould of the nasal cavity was constructed. Using an alginate paste an impression of the left nasal vestibule and the tumor was obtained, together with the right nasal cavity and upper lip. The latter in order to assure placement of the mould into a fixated position. The alginate model was duplicated in methyl metacrylate, in which two parallel plastic afterloading catheters were placed at a distance of 9-10 mm from each other. It was ensured that the catheters were positioned in the same plane, 2 mm underneath and parallel to the medial surface of the acrylic mould at the left side (Fig. 1). A reconstruction of the catheters in the mould was made and a pre-planned dose distribution was calculated with the NPS computer program. In each catheter an active length of 3.5 cm was chosen in order to deliver an adequate dose to the target volume including the tumor with a 0.5-cm margin. To encompass the whole tumor thickness in the transversal direction the isodose level at a 3-mm distance to the medial outer surface of the mould in the midplane was taken as the reference isodose. This is at a 5-mm distance to the plane of the sources in the same direction. The prescribed dose at the refer-
Correspondence to: L.A.M. Pop, Institute of Radiotherapy, University of Nijmegen, Nijmegen, The Netherlands.
70
Through ( 0,
O.
source 3 69Cl
3S~
03
Ir-leZ
Scale. 4ool Dose : coy Coord syste~ Interactive
A
AZ~ R m d l o ~ b ~ p ~
-y 70s -axis Thr°ugh ( o. o.
~
3sJ z35
o)
3 ~gc1 I r - l g 2 Scale 4001 Dose : cGy Coord system Interactive
/
up~ .9
Fig. 2. Dose distribution around the catheters. The isodose of 470 cGy is taken as the referenceisodose. A, Central plane, defined as the plane perpendicular to the midlines of the active part of each catheter (i.e., the transversal plane). The reference isodose of 470 cGy is located at 3 mm to the outer surface of the mould at the medial side and at 5 mm to the plane of the catheters. B, Coronal plane just between the two catheters. Fig. 1. Anterior (A) and lateral (B) view of the mould with the two parallelcatheters placed in the left side of the mould with a mutual distance of I cm. The catheters, located in the same plane, are best seen at the lateral view.
ence isodose was chosen to be 4.7 Gy, requiring a dwell time of 7.2 s for each position of the high activity pointsource (actual activity 3.69 Ci) of the HDR-microSelectron. There were, respectively seven source positions with a stepsize of 5 mm in each catheter. As shown in Fig. 2 the 4.7-Gy isodose encompassed the entire target volume in all planes, while the higher doses in the near vicinity of the sources are located within the tissue equivalent material of the mould. Subsequently, the mould was introduced in the patient's nasal cavity and fixed with adhesive tape. AP and lateral isocentric radiographs were taken and a reconstruction of the mould and nasal cavity was made. Calculation of the isodose profiles was performed in the coronal, sagittal and transversal planes. The position of the reference isodose as assumed in the predictive dosimetry and the dose homogeneity were checked in the different planes. With 4.7 Gy delivered at the reference isodose the actual doses applied in the tumor and the surrounding normal tissues were as precalculated. Based on the experience with low dose rate irradiation in which 60-65 Gy is given
at a dose rate of 40-60 cGy/h, a dose equivalent radiation scheme for fractionated high dose rate irradiation was calculated with the use of the incomplete repair model of Thames [11]. We choose a low dose rate irradiation scheme of 65 Gy at a dose rate of 50 cGy?h as reference for both local tumor control and maximal tolerated dose regarding normal tissues. We assumed an tx/B ratio of 10 Gy and a repair halftime of 0.5 h for the tumor tissue and 3 - 4 Gy and 1.5 h for the late-reacting normal tissues, such as cartilage and fibrous tissue. A HDR-fractionated irradiation scheme delivering ten fractions of 4.7 Gy, two fractions per day and with an interval of 8 h was calculated to be biologically equivalent to the low dose rate reference schedule as to tumor control probability. Regarding the normal tissues, an excess of 5-10% of the biological effect of the HDR irradiation scheme as compared to 65 Gy at a (low) dose rate of 50 cGy/h was accepted. Two fractions per day were delivered for 5 consecutive days, each first fraction at 09:00 h and the second at 17:00 h. After each fraction the mould was removed from the nasal cavity and the patient went home. The placement of the mould turned out to be easy, nontraumatic and painless. The position of the mould and thus the dose distribution was reproducible, as was verified by repeated X-ray films.
71
Follow-up results The treatment was tolerated very well. Only minor acute side-effects were observed. Two weeks after completion of radiotherapy there was a brisk redness of the mucosa of the nasal cavity with no complaints of pain. At the moment of this report, two years later, the patient is without complaints and without evidence of disease. There is a slight atrophy and dryness of the mucosa, with no late effects of the skin of the nose and the upper lip. There is no evidence of chondritis of the nasal septum.
Discussion Early squamous cell carcinoma of the nasal vestibule is a relatively rare disease. Primary treatment is historically based on surgery or external beam radiotherapy. During the last two decades, the use of low dose rate brachytherapy became increasingly important, with excellent results in terms of local control and cosmesis [2,6-10,12,13]. This report describes a new brachytherapeutic approach using fractionated high dose rate intracavitary irradiation, which turned out to be feasible. We believe that this technique using a mould and a HDR remote afterloading machine has several advantages over low dose rate interstitial irradiation. For implantation of needles for low dose rate interstitial irradiation (LDR-IRT) the patient has to be hospitalized and usually needs general anaesthesia. During the treatment time of the LDR-IRT, mostly 5 - 6 days, the patient must be isolated in a specially designed radioprotected room, which complicates nursing and visiting. This could be accompanied with psychological distress for the patient. Our technique is not invasive, painless and allows treatment on an out-patient basis. A stable and reproducible source position is guaranteed during the short time of each fraction of the HDR irradiation. The fixed, pre-planned geometry of the catheters makes forecast of dosimetry possible. If the pre-planned dose distribution in the target volume is not adequate, the catheters can be replaced. The dose homogeneity is improved with the use of this technique, while higher doses in the near vicinity of the sources are located within the tissue-equivalent material of the mould. Moreover, the dose distribution in relation to the tumor and the surrounding normal tissues can be verified before each
fraction and small deviations can be corrected with an optimization computerprogram. A technique which makes use of a mould and almost medium dose rate has been described by Haynes and Tapley [6]. It has some of the advantages of our technique, but the use of radium as a radioactive source is not recommended because of the undesirable radiation exposure of patient, physician and nurses. It also does not allow optimization of dose distribution. With low dose rate irradiation at a dose rate of 50 cGy/h and a total dose of 65 Gy as used in clinical practice, tumor control is excellent, while the late-reacting normal tissues are expected and proven to be maximally spared [2,6-10,12,13]. However, from a radio-biological point of view, a dose equivalent radiation scheme with regard to both local tumor control and normal tissue tolerance can be approached by delivering the HDR irradiation in ten fractions of 4.7 Gy, with a time interval between each fraction of at least 8 h [4,11]. It is not in the scope of this paper to further discuss dose rate effects and fractionation. So far, 2 years later, the patient has no evidence of disease and shows no significant late side-effects. However, follow up is still short and experience too limited to be conclusive about definite local control and late effects on normal tissues.
Conclusion We feel that this technique of high dose rate intracavitary brachytherapy is certainly worth considering in lieu of low dose rate interstitial irradiation for early lesions of the nasal vestibule. The use of a mould is a noninvasive procedure and yields a predictable and reproducible distribution of the radiation dose closely fitting the tumor volume, while the surrounding normal tissues are maximally spared by the rapid dose fall-off. However, for more extensive and infiltrating lesions we still prefer interstitial brachytherapy either alone or combined with external beam irradiation.
Acknowledgements The authors wish to thank M.E. van Leer, M.D. and J. van Lokven from the department of Removable and Maxillo-facial Prosthodontics for their cooperation in constructing the mould.
References 1 Boulos, E. External rhinoplasty approach for lesions of the nasal vestibule. Laryngoscope 94: 703-704, 1984. 2 Chassagne, D. and Wilson, F. Brachytherapy of carcinomas of the nasal vestibule. Int. J. Radiat. Oncol., Biol. Phys. 10: 761, 1984. 3 De Jong, J. M. A., Schalekamp, W. and Hordijk, G. J. Squamous cell carcinoma of the nasal vestibule. Clin. Otolaryngol. 6: 205-208, 1981. 4 Fowler, J.F. The radiobiology of brachytherapy. In: Brachytherapy HDR and LDR, pp. 121-137. Editors: A.A. Martinez, C.G. Orton and R.F. Mould. Nucletron Corporation, Columbia, 1990. 5 Goepfert, H., Guillamondequi, O. M., Jesse, R. H. and Lindberg, R.D. Squamous cell carcinoma of the nasal vestibule. Arch. Otolaryngol. 100: 8-10, 1974.
6 Haynes, W. D. and Tapley, N. Radiation treatment of carcinoma of the nasal vestibule. Am. J. Roentgenol. 120: 595-602, 1974. 7 Kagan, R. A., Nussbaum, H., Rao, A., Chan, P., Gilbert, H., Hintz B., Ryoo, M., Miles, J. and Rice, D. The management of carcinoma of the nasal vestibule. Head Neck Surg. 4: 125-128, 1981. 8 Levendag, P.C. and Pomp, J. Radiation therapy of squamous cell carcinoma of the nasal vestibule. Int. J. Radiat. Oncol., Biol. Phys. 19: 1363-1367, 1990. 9 Mazeron, J. J., Chassagne, D., Crook, J., Bachelot, F., Brochet, F., Brune, D., Brunin, F., Bunesco, N., Daly, N., Danczak, S., Dubois, J. B., Grangean, M., Hoffstetter, S., Koechlin, M., Huart, J., Labib, A., Madelain, M., Maylin, C., ReynaudBouggnoux, A., Rozan, R. and Serpantie, P. Radiation therapy
72 of carcinomas of the skin of nose and nasal vestibule; A report of 1676 cases by the Groupe Europcen de Curietherapie. Radiother. Oncol. 13: 165-173, 1989. 10 Mendenhall, N. P., Parsons, J. T., Cassisi, N. J. and Million, R. R. Carcinoma of the nasal vestibule. Int. J. Radiat. Oncol., Biol. Phys. 10: 627-637, 1984. 11 Thames, H.D. An incomplete repair model for survival after
12 13
fractionated and continuous irradiation. Int. J. Radiat. Biol. 47: 319-339, 1985. Wang, C.C. Treatment of carcinoma of the nasal vestibule by irradiation. Cancer 38: 100-106, 1976. Wong, C. S. and Cummings, B.J. The place of radiation therapy in the treatment of squamous cell carcinoma of the nasal vestibule - - a review. Acta Oncol. 27: 203-208, 1988.