Communication of NARILIS researcher, Dr Eléonore Longton, ranked amongst the most relevant and major presentations of the 2015 ASTRO Annual Meeting!

Clinically node negative (cN0) head and neck squamous cell carcinoma (HNSCC) patients have a risk ranging between 18 and 45% of occult metastases, making prophylactic irradiation mandatory. Dr Jean-François Daisne previously demonstrated, in a prospective phase I study, the potential of sentinel lymph node SPECT/CT lymphoscintigraphy to individually predict cervical subregions requiring prophylactic irradiation. Dr Eléonore Longton now pursues a phase II study to evaluate its oncological safety.

In October 2015, Dr Eléonore Longton participated to the annual meeting of the American Society for Radiation Oncology (ASTRO) in San Antonio. During this conference, she presented an oral communication entitled “Individualized Super Selective Nodal Radiation Therapy for cN0 Head and Neck Squamous Cell Carcinoma Patients Based on Sentinel Node(s) Identification: A Prospective Phase 2 Study of SPECT/CT-guided volume de-escalation”.

Her research work was recognized as one of the most relevant and highly influential new data from the ASTRO annual meeting. Her abstract was therefore selected for discussion at the 2015 Best of ASTRO meeting, which took place in San Diego in November 2015.

In addition, her abstract, designated amongst the Best of ASTRO, is now also part of a new educational program, the Best of ASTRO Licensed Package.

ABSTRACT

Individualized Super Selective Nodal Radiation Therapy for Clinically Negative Lymph Nodes (cN0) in Head and Neck Squamous Cell Carcinoma Patients Based on Sentinel Node(s) Identification: A Prospective Phase 2 Study of SPECT/CT-guided Volume De-escalation

International Journal of Radiation Oncology*Biology*Physics, Volume 93, Issue 3, Supplement, 1 November 2015, Pages S71-S72

E. Longton^{1, 2}, G. Lawson^{2, 3}, J. Installé¹, B. Bihin^{2, 4}, M. Laloux¹, T. Vander Borght^{2, 3}, I. Mathieu¹, K. Thevissen⁵, J.F. Daisne^{1, 2}

¹ Clinique et maternité Sainte-Elisabeth, Namur, Belgium, ² NARILIS, Namur, Belgium, ³ UCL-CHU Dinant-Godinne, Yvoir, Belgium, ⁴ University of Namur, Namur, Belgium, ⁵ CH Mouscron, Mouscron, Belgium

Purpose/Objective(s)

Due to a risk of 18% to 45% of occult metastases among the clinically free of nodes head and neck squamous cell carcinoma (HNSCC) patients, prophylactic neck irradiation is often mandatory. Based on international guidelines for the selection of the neck node levels, this prophylactic treatment still leads to unnecessary large irradiation of normal tissues because bilateral drainage is the rule in only 30% to 50% of individuals, and 15% to 30% of the tumors drain in unpredicted nodal basins. Sentinel lymph node (SLN) single-photon emission computerized tomography (SPECT/CT) lymphoscintigraphy makes it possible to individually predict cervical subregions requiring prophylactic irradiation in cN0 patients. This ongoing prospective phase 2 study analyzes its oncological safety.

Materials/Methods

Twenty-one patients with newly diagnosed cN0 SCC of the oral cavity, oropharynx, larynx, or hypopharynx were included. All patients were imaged with SPECT/CT after 99mTc nanocolloid injection around the tumor. The neck levels containing up to 4 hottest nodes were identified and selected for prophylactic irradiation (CTVn-LS) by volumetric modulated arc therapy. A comparative virtual planning was performed with volumes selected according to international guidelines (CTVn-IG).

Results

Migration was observed in all of the 21 patients (1 with gamma probe only) with an average of 2.7 sentinel nodes detected per patient. CTVn-LS was totally encompassed by CTVn-IG in all patients but 2 with an unpredicted drainage in retropharyngeal levels. On average, CTVn-LS and related planning target volume (PTV) were 2 times smaller than IG ones. This led to significant dose decrease in identified organs at risk as well as remaining volume at risk. With a median follow-up of 14 months, no regional relapse was observed, while 2 patients had a local one (9%). Currently, 3 patients have died (1 patient from geriatric degradation and 2 experienced fatal local relapse).

Conclusion

SPECT/CT lymphoscintigraphy of SLN allows individualization of prophylactic node CTV in cN0 HNSCC patients eligible for definitive radiation therapy. Both CTV and PTV are significantly reduced, which results in a significant dose decrease in all identified organs at risk. At a median follow-up of 14 months, no regional relapse was observed, but further follow-up and recruitment are necessary to ensure the oncological safety.