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Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

521 - Patterns of Local Failures and Suggestions for Reduction of Clinical Target Volume for Nasopharyngeal Carcinoma Patients Without Cervical Lymph Node Metastasis

Date

21 Oct 2018

Session

Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

Topics

Tumour Site

Head and Neck Cancers

Presenters

Chaosu Hu

Citation

Annals of Oncology (2018) 29 (suppl_8): viii372-viii399. 10.1093/annonc/mdy287

Authors

C. Hu, Y. Li

Author affiliations

  • Department Of Radiation oncology, Fudan University Shanghai Cancer Center, 200032 - Shanghai/CN
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Resources

Abstract 521

Background

To investigate the initial irradiated dose of the recurrent site and local failures patterns after Intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) patients with retropharyngeal lymph nodes (RLNs) metastasis only, with the aim to demonstrate the adequacy and overall quality of the target volume definitions for further improvement of outcome and therapeutic ratio.

Methods

382 newly diagnosed non-metastatic NPC patients were retrospectively enrolled, receiving elective neck irradiation to to levels II, III, VA. For patients with local failure, the location and extent of local failures were transferred to the pretreatment planning CT for dosimetric analysis. The dose of radiation received by GTVr (gross tumor volume of recurrence) was calculated and analyzed with dose-volume histogram (DVH). Failures were classified as: "in field" if 95% of GTVr was within the 95% isodose, "marginal" if 20% to 95% of GTVr was within the 95% isodose, or "outside" if less than 20% of GTVr was inside the 95% isodose.

Results

With a median follow-up time of 61.3 months, 12 patients have developed local recurrence (10 cases available). The 5-year OS, LRFS, RRFS, DMFS and DFS were 87.8%, 95.2%, 99.1%, 93.3% and 82.5%, respectively. Dose conformity with IMRT was excellent and the recurrence was mainly within 3 years after the first treatment. The dosimetric analysis showed that 7 failures were classified as "in-field", 2 failures as "marginal" and only 1 failures as "out-field". Most local relapse site located just the same site of primary tumor and most anatomic sites were at low risk of concurrent bilateral tumor invasion.

Conclusions

IMRT with elective neck irradiation provides excellent local control for NPC patients without cervical lymph node metastasis. In-field failures are the main patterns for local recurrence and the radioresistant subvolumes within the GTV are needed to be identified. We proposed suggestions for reduction of target volume during IMRT treatment for NPC patients.

Clinical trial identification

Legal entity responsible for the study

Fudan University Shanghai Cancer Center.

Funding

Has not received any funding.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.

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