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Conference Paper: Re-irradiation in Nasopharyngeal Cancer

TitleRe-irradiation in Nasopharyngeal Cancer
Authors
Issue Date2010
Citation
The 29th Annual Meeting of the European Society for Therapeutic Radiology and Oncology (ESTRO 29), Barcelona, Spain, 12-16 September 2010 How to Cite?
DescriptionBecause of the anatomical proximity to critical structures, radical surgical resection is very difficult for nasopharyngeal cancer. Radiotherapy is the mainstay modality for primary treatment, and re-irradiation with or without chemotherapy is the only option for the majority with recurrence with infiltration beyond the nasopharynx. Aggressive treatment should be attempted as far as possible because long-term survival might still be achievable. Various radiotherapy methods have been used (including external radiotherapy with different techniques, stereotactic radiosurgery/ radiotherapy, and/or brachytherapy using intracavitary and interstitial modes); the reported outcome will be presented. The general consensus is that re-irradiation doses 60 Gy are needed for effective salvage, but high risk of late toxicities is a serious concern. Past retrospective analyses of 654 patients with re-irradiation by Lee et al. (1997) showed that the most significant factors affecting the chance of local salvage were the stage of disease at detection of recurrence and the radiation dose during the second course; the dose of the primary course had little impact. Further comparison of the late toxicity rate in 487 patients with two courses of external radiotherapy versus 3635 patients with one course (Lee et al., 2000) showed the post-retreatment toxicity rate was affected significantly by the biologically effective dose of the first course (p = 0.01) and marginally by that of the second course (p = 0.06). If the summated total biologically effective dose (assuming an a/b ratio of 3 Gy) was taken as the dose unit for patients with re-irradiation, it was estimated that a summated dose of 143 Gy3 would induce 5-year toxicity rate of 20%, while the corresponding dose for patients with one course was 111 Gy3. The findings suggested that there was partial recovery of normal tissues following the primary course, the cumulative dose that could be tolerated was 129% that of single course. However, these were only gross estimates based on patients irradiated with conventional 2-dimensional technique, further validation is needed. Recent analyses of patients treated in our center from 1994 to 2008 showed that 85 patients had re-irradiation for local ± nodal failure; their 5-year disease-specific survival was 31% from time of recurrence (63% from primary diagnosis). Their 5-year late toxicity rate (Grade ≥ 3) was significantly higher than the 1227 patients with only one course of radiotherapy (51% vs 25%, p < 0.001). Details of doses and messages learnt will be presented Re-irradiation remains one of the most difficult challenges, particularly for patients who recurred despite aggressive primary treatment with adequate coverage. The advent of radiotherapy technology brings exciting opportunities for precision and highly conformal dose coverage. More data on tolerance doses for different organs at risk are needed.
Persistent Identifierhttp://hdl.handle.net/10722/220909
ISSN
2015 Impact Factor: 4.817
2015 SCImago Journal Rankings: 2.654

 

DC FieldValueLanguage
dc.contributor.authorLee, WMA-
dc.date.accessioned2015-10-22T09:14:28Z-
dc.date.available2015-10-22T09:14:28Z-
dc.date.issued2010-
dc.identifier.citationThe 29th Annual Meeting of the European Society for Therapeutic Radiology and Oncology (ESTRO 29), Barcelona, Spain, 12-16 September 2010-
dc.identifier.issn0167-8140-
dc.identifier.urihttp://hdl.handle.net/10722/220909-
dc.descriptionBecause of the anatomical proximity to critical structures, radical surgical resection is very difficult for nasopharyngeal cancer. Radiotherapy is the mainstay modality for primary treatment, and re-irradiation with or without chemotherapy is the only option for the majority with recurrence with infiltration beyond the nasopharynx. Aggressive treatment should be attempted as far as possible because long-term survival might still be achievable. Various radiotherapy methods have been used (including external radiotherapy with different techniques, stereotactic radiosurgery/ radiotherapy, and/or brachytherapy using intracavitary and interstitial modes); the reported outcome will be presented. The general consensus is that re-irradiation doses 60 Gy are needed for effective salvage, but high risk of late toxicities is a serious concern. Past retrospective analyses of 654 patients with re-irradiation by Lee et al. (1997) showed that the most significant factors affecting the chance of local salvage were the stage of disease at detection of recurrence and the radiation dose during the second course; the dose of the primary course had little impact. Further comparison of the late toxicity rate in 487 patients with two courses of external radiotherapy versus 3635 patients with one course (Lee et al., 2000) showed the post-retreatment toxicity rate was affected significantly by the biologically effective dose of the first course (p = 0.01) and marginally by that of the second course (p = 0.06). If the summated total biologically effective dose (assuming an a/b ratio of 3 Gy) was taken as the dose unit for patients with re-irradiation, it was estimated that a summated dose of 143 Gy3 would induce 5-year toxicity rate of 20%, while the corresponding dose for patients with one course was 111 Gy3. The findings suggested that there was partial recovery of normal tissues following the primary course, the cumulative dose that could be tolerated was 129% that of single course. However, these were only gross estimates based on patients irradiated with conventional 2-dimensional technique, further validation is needed. Recent analyses of patients treated in our center from 1994 to 2008 showed that 85 patients had re-irradiation for local ± nodal failure; their 5-year disease-specific survival was 31% from time of recurrence (63% from primary diagnosis). Their 5-year late toxicity rate (Grade ≥ 3) was significantly higher than the 1227 patients with only one course of radiotherapy (51% vs 25%, p < 0.001). Details of doses and messages learnt will be presented Re-irradiation remains one of the most difficult challenges, particularly for patients who recurred despite aggressive primary treatment with adequate coverage. The advent of radiotherapy technology brings exciting opportunities for precision and highly conformal dose coverage. More data on tolerance doses for different organs at risk are needed.-
dc.languageeng-
dc.relation.ispartofThe 29th Annual Meeting of the European Society for Therapeutic Radiology and Oncology (ESTRO 29)-
dc.titleRe-irradiation in Nasopharyngeal Cancer-
dc.typeConference_Paper-
dc.identifier.emailLee, WMA: awmlee@hkucc.hku.hk-
dc.identifier.authorityLee, WMA=rp02056-
dc.identifier.hkuros266838-
dc.publisher.placeBarcelona, Spain-

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