Mapping of sentinel lymph node drainage using SPECT/CT to tailor elective nodal irradiation in head and neck cancer patients (SUSPECT-2): a single-center prospective trial.

BACKGROUND: The majority of patients with head and neck squamous cell carcinoma (HNSCC) receive bilateral elective nodal irradiation (ENI), in order to reduce the risk of regional failure. Bilateral ENI, as compared to unilateral ENI, is associated with higher incidence of acute and late radiation-induced toxicity with subsequent deterioration of quality of life. Increasing evidence that the incidence of contralateral regional failure (cRF) in lateralized HNSCC is very low (< 10%) suggests that it can be justified to treat selected patients unilaterally. This trial aims to minimize the proportion of patients that undergo bilateral ENI, by using lymph drainage mapping by SPECT/CT to select patients with a minimal risk of contralateral nodal failure for unilateral elective nodal irradiation. METHODS: In this one-armed, single-center prospective trial, patients with primary T1-4 N0-2b HNSCC of the oral cavity, oropharynx, larynx (except T1 glottic) or hypopharynx, not extending beyond the midline and planned for primary (chemo) radiotherapy, are eligible. After 99mTc-nanocolloid tracer injection in and around the tumor, lymphatic drainage is visualized using SPECT/CT. In case of contralateral lymph drainage, a contralateral sentinel node procedure is performed on the same day. Patients without contralateral lymph drainage, and patients with contralateral drainage but without pathologic involvement of any removed contralateral sentinel nodes, receive unilateral ENI. Only when tumor cells are found in a contralateral sentinel node the patient will be treated with bilateral ENI. The primary endpoint is cumulative incidence of cRF at 1 and 2 years after treatment. Secondary endpoints are radiation-related toxicity and quality of life. The removed lymph nodes will be studied to determine the prevalence of occult metastatic disease in contralateral sentinel nodes. DISCUSSION: This single-center prospective trial aims to reduce the incidence and duration of radiation-related toxicities and improve quality of life of HNSCC patients, by using lymph drainage mapping by SPECT/CT to select patients with a minimal risk of contralateral nodal failure for unilateral elective nodal irradiation. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03968679, date of registration: May 30, 2019.

SPECT/CT-guided elective nodal irradiation for head and neck cancer is oncologically safe and less toxic: A potentially practice-changing approach.

BACKGROUND AND PURPOSE: Bilateral elective nodal irradiation (ENI) remains the standard treatment for head and neck squamous cell carcinoma (HNSCC). Unilateral ENI could reduce treatment toxicity and improve health-related quality-of-life (HRQOL). This prospective proof-of-principle trial (NCT02572661) investigated the feasibility, safety and clinical benefits of SPECT/CT-guided ENI of the node-negative contralateral neck. MATERIALS AND METHODS: Patients with lateralized T1-3N0-2bM0 HNSCC of the oropharynx, oral cavity, larynx and hypopharynx underwent SPECT/CT after peritumoral 99mTc-nanocolloid injection. Patients without contralateral lymph drainage received ipsilateral ENI only. If lymph drainage to only one contralateral hot spot was visible, ENI to the contralateral neck would be limited to only the level containing the hot spot. The primary endpoint was the incidence of contralateral regional failure (CRF) at 2 years. Toxicity and HRQOL were compared with a 1:1 matched historical cohort that received standard bilateral ENI (B-ENI) with identical planning and treatment techniques. RESULTS: Fifty patients were treated with SPECT/CT-guided ENI. After a median follow-up of 33 months (range 18-45), CRF was observed in one patient (2%; 95% confidence interval: 0-6%). Compared to the matched B-ENI group, patients treated with SPECT/CT-guided ENI had significantly lower incidences of grade ≥2 dysphagia (54% vs. 82%; p < 0.001), tube feeding (10% vs. 50%; p < 0.001) and late grade ≥2 xerostomia (9% vs. 54%; p < 0.001). Significant and clinically relevant HRQOL benefits of SPECT/CT-guided ENI were observed on the EORTC QLQ-C30 summary score, and QLQ-HN35 swallowing and dry mouth subscales. CONCLUSION: SPECT/CT-guided ENI is associated with a low risk of contralateral regional failure. Compared to B-ENI, SPECT/CT-guided ENI significantly reduces dysphagia, feeding tube placement, and late xerostomia and improves HRQOL.

SPECT/CT-guided elective nodal irradiation for head and neck cancer: Estimation of clinical benefits using NTCP models.

BACKGROUND AND PURPOSE: The great majority of patients with lateralized head and neck squamous cell carcinoma (HNSCC) treated with radiotherapy routinely undergo bilateral elective nodal irradiation (ENI), even though the incidence of contralateral regional failure after unilateral ENI is low. Excluding the contralateral neck from elective irradiation could reduce radiation-related toxicity and improve quality-of-life. The current study investigated the dosimetric benefits of a novel approach using lymph drainage mapping by SPECT/CT to select patients for unilateral ENI. PATIENTS AND METHODS: Forty patients with lateralized cT1-3N0-2bM0 HNSCC underwent lymph drainage mapping. Two radiation plans were made; the real plan with which patients were actually treated (selective SPECT/CT-guided plan irradiating the ipsilateral neck ±â€¯any contralateral draining level); and the virtual plan (standard plan according to institutional guidelines, as if the same patient would have been treated bilaterally). Radiation doses to clinically important organs-at-risk were compared between the two plans. We used five normal tissue complication probability (NTCP) models to predict the clinical benefits of this approach. RESULTS: Median dose reductions to the contralateral parotid gland, contralateral submandibular gland, glottic larynx, supraglottic larynx, constrictor muscle and thyroid gland were 19.2, 27.3, 11.4, 9.7, 12.1 and 18.4 Gy, respectively. Median NTCP reductions for xerostomia, contralateral parotid function, dysphagia, hypothyroidism and laryngeal edema were 20%, 14%, 10%, 20% and 5% respectively. CONCLUSIONS: Selective SPECT/CT-guided ENI results in significant dose reductions to various organs-at-risk and corresponding NTCP values, and will subsequently reduce the incidence and severity of different troublesome radiation-related toxicities and improve quality-of-life.