Safety of contralateral submandibular gland sparing in locally advanced oropharyngeal cancers: A multicenter review

Diffusion weighted imaging in submandibular gland sparing helical tomotherapy for nasopharyngeal carcinoma

PURPOSE

To verify clinical significance of submandibular gland (SMG)-sparing during helical tomotherapy (HT) for nasopharyngeal carcinoma (NPC) from the perspective of imaging by using diffusion weighted imaging (DWI).

MATERIALS AND METHODS

In this prospective study, 60 NPC patients scheduled for radical SMG-sparing HT were enrolled. All patients underwent DWI examinations prior to HT (pre-HT) and 1, 3, 6, 9, 12 months post HT. Mean apparent diffusion coefficient (ADC) values of bilateral parotid glands (PGs) and submandibular glands (SMGs) were measured. Differences of ADC and changes of ADC pre and pro HT (ΔADC) among SMG-spared, SMG-unspared and PGs were compared and the associations betweenΔADC and variations of patient-rated xerostomia questionnaire summary scores (XQ-sum) were further tested.

RESULTS

ADC_post-HT and ΔADC_post-HT of SMG-spared were both much lower than of SMG-unspared and a strong dose-response relationship was detected between mean radiation dose and ΔADC of SMGs. Dynamic change trends of PGs, SMG-spared and SMG-unspared were similar, with initial increase at 1 m-post-HT followed by little change at 3 m-post-HT and then gradual decrease over time. But for SMG-unspared, there was no obvious change of ADC from 6 m-post-HT to 12 m-post-HT. The dynamic change trend of XQ-sum was nearly in line with that of ADC on the whole. And a positive correlation between mean ΔADC_1m-post-HT of bilateral SMGs and variation of XQ-sum_1m-post-HT in patients with bSMG-unspared were found (r = 0.693, P < 0.001). Multivariate stepwise regression analysis showed that whether spared SMG or not was the only independent predictor correlated to XQ-sum_post-HT at each follow-up timepoint.

CONCLUSION

SMG-sparing technique could significantly improve subjective xerostomia post HT in NPC patients from the perspective of imaging.

Erythropoietin Plays a Protective Role in Submandibular Gland Hypofunction Induced by Irradiation

PURPOSE

This study aims to explore the radioprotective effects of recombinant human erythropoietin (rhEPO) on rats' submandibular gland hypofunction induced by irradiation (IR).

MATERIALS AND METHODS

Thirty rats were divided into 3 groups: 1) control group, 2) IR group, and 3) IR + rhEPO group. The IR group and IR + rhEPO group received a single dose of 15 Grays (Gy) (0.98 Gy/min), plus, the IR + rhEPO group also received subcutaneous administration of rhEPO at a dose of 3,000 IU/kg body weight 3 days before irradiation and then repeated every 24 hours for the first 2 weeks after irradiation. Immunohistochemistry analysis to erythropoietin receptor was performed to detect the levels of erythropoietin receptor in submandibular glands with or without radiation. Ninety days after irradiation, the salivary flow rates were assessed, and the submandibular gland of every rat was subjected to hematoxylin and eosin staining and immunohistochemical staining with antiaquaporin 5 and anti-proliferating cell nuclear antigen antibodies. Apoptosis was examined by the terminal deoxynucleotidyl transferase biotin-dUDP nick end-labeling assay. In addition, to examine the protective role of rhEPO on human submandibular gland cells, the apoptotic and proliferation rate of cells under a radiation dose of 8 Gy was detected. One-way analysis of variance was carried out to analyze the results of each group, and the P value was set at 0.05.

RESULTS

Erythropoietin receptor was expressed in the submandibular glands at a low level under normal conditions but upregulated after irradiation. rhEPO administration remarkably alleviated gland atrophy, increased salivary flow rates with upregulation of aquaporin-5 compared with the IR group. In addition, fewer apoptotic cells and more proliferative cells were observed in the IR + rhEPO group compared with the IR group, both in vivo and in vitro.

CONCLUSIONS

rhEPO administration may be a useful countermeasure to mitigate submandibular gland hypofunction after therapeutic radiation exposure.

Modified technique of submandibular gland transfer followed by intensity modulated radiotherapy to reduce xerostomia in head and neck cancer patients

BACKGROUND

Xerostomia is one of the most common long-term adverse effects of radiotherapy for head and neck cancer patients. Contralateral submandibular gland transfer (SMG-T) before radiotherapy was shown to reduce xerostomia compared to pilocarpine. We sought to evaluate a modification of this surgery preserving the ipsilateral facial artery and vein to simplify the SMG-T.

METHODS

Eighteen patients planned for head and neck intensity modulated radiotherapy to both necks were reviewed. Surgical complications were recorded. The grade of xerostomia was assessed after treatment completion.

RESULTS

There were no minor or major complications resulting from the modified SMG-T. At 24.5-months follow up, the incidence of post-treatment moderate to severe xerostomia was 16.7%. No locoregional recurrence occurred. Only one patient had distant solitary lung metastasis.

CONCLUSION

The modified SMG-T technique is a practical and effective method to reduce the dose of radiation to the contralateral SMG and limit post-treatment xerostomia.

Regional Radiation Therapy for Oropharyngeal Cancer in the HPV Era

Oropharyngeal carcinoma associated with the human papillomavirus is increasing in incidence and represents a unique head and neck disease with favorable treatment outcomes. This review evaluates the evolving role of radiotherapy in regional management with an overall goal of treatment de-escalation in the appropriate patient. Determining the optimal approach and selection factors for treatment de-escalation is under active investigation. Response to induction chemotherapy, refining adverse pathologic factors after a primary surgical approach, decreasing radiation dose with or without chemotherapy in the definitive or adjuvant settings as well as more selective nodal level irradiation all are current strategies for treatment de-escalation. This review details the likely changes in regional radiotherapy management for oropharyngeal carcinoma in the modern human papillomavirus era and discusses future approaches to patient selection with the goal of reducing toxicities while maintaining function preservation and quality of life in group of patients who are younger and healthier than traditional head and neck cancer patients.

Five-year outcomes of sparing level IB in node-positive, human papillomavirus-associated oropharyngeal carcinoma: A safety and efficacy analysis

INTRODUCTION

The conformality of modern intensity modulated radiation therapy (IMRT) allows avoidance of the submandibular glands (SMG) in select patients, potentially improving late xerostomia. This study explores the safety and efficacy of this approach in select oropharyngeal carcinoma (OPC) patients.

METHODS

Patients with T1-2N+ human papillomavirus (HPV)-associated OPC treated with definitive IMRT at one institution from 2009 to 2014 were identified. Patients were divided into 3 groups: bilateral level IB targeted (A, n = 16), a single level IB targeted (B, n = 61), and bilateral IB spared (C, n = 9). Outcomes were reviewed to identify the rate of level IB regional recurrence. Odds ratios were calculated for xerostomia between groups.

RESULTS

Level Ib was targeted in 93 instances (54.1%) and avoided in 79 instances (45.9%). Mean SMG doses were significantly lower when level IB was spared compared to when targeted (37.5 Gy vs 67.5 Gy; P < 0.0001). Median doses to oral cavity decreased with increasing level Ib sparing (40.7 Gy [A] vs 35.4 Gy [B] vs 30.7 [C]; P = 0.002). The rate of late grade ≥2 xerostomia was significantly lower in patients with bilateral 1b sparing (53% in A vs 0% in C; P = 0.007). Sparing 1b unilaterally resulted in a non-significant decrease in late grade ≥2 xerostomia (P = 0.181). No regional failures were identified in levels IB (median follow up = 59.3 months).

CONCLUSION

Sparing level IB is safe in T1-2N+ HPV+ OPC. Avoiding level Ib translates into significantly lower SMG and oral cavity doses. Larger studies are needed to validate these findings and the impact of this technique.

Long-term outcomes of interventions for radiation-induced xerostomia: A review

Xerostomia, or dry mouth, is a significant problem affecting quality of life in patients treated with radiation therapy for head and neck cancer. Strategies for reduction of xerostomia burden vary widely, with options including: sialagogue medications, saliva substitutes, acupuncture, vitamins, hyperbaric oxygen, submandibular gland transfer, and acupuncture or associated treatments. In this review, we sought to evaluate long-term outcomes of patients treated with various interventions for radiation-induced xerostomia. A literature search was performed using the terms "xerostomia" and "radiation" or "radiotherapy"; all prospective clinical trials were evaluated, and only studies that reported 1 year follow up were included. The search results yielded 2193 studies, 1977 of which were in English. Of those, 304 were clinical trials or clinical studies. After abstract review, 23 trials were included in the review evaluating the following treatment modalities: pilocarpine (three); cevimeline (one); amifostine (eleven); submandibular gland transfer (five); acupuncture like transcutaneous electrical nerve stimulation (ALTENS) (one); hyperbaric oxygen (one); and acupuncture (one). Pilocarpine, cevimeline, and amifostine have been shown in some studies to improve xerostomia outcomes, at the cost of toxicity. ALTENS has similar efficacy with fewer side effects. Submandibular gland transfer is effective but requires an elective surgery, and thus may not always be appropriate or practical. The use of intensity-modulated radiation therapy, in addition to dose de-escalation in select patients, may result in fewer patients with late xerostomia, reducing the need for additional interventions.

Selectively sparing the submandibular gland when level Ib lymph nodes are included in the radiation target volume: An initial safety analysis of a novel planning objective

BACKGROUND

Submandibular gland (SMG) metastases are extremely rare in head and neck cancer, even in the presence of level Ib lymph node (LN) involvement. In recent years, we have contoured the SMG and specifically attempted to limit its dose exposure even in patients in whom the level Ib LN station is targeted. This study reports our preliminary feasibility and safety experience with selective submandibular gland sparing.

METHODS

Patients with squamous cell cancer (SCC) of the oral cavity or oropharynx with T1-2, N0-3, M0 disease in whom at least a single level Ib lymph node region was included in the target volume were identified. All patients were treated from 2009 to 2014 with definitive or postoperative IMRT with or without chemotherapy. Patients with recurrent disease, previous radiation or treated palliatively were excluded.

RESULTS

A total of 174 patients met criteria for inclusion. Among the 185 level Ib LN stations that were deliberately targeted in the clinical treatment volume, 32 submandibular glands were contoured, excluded from the target volume and avoided during treatment planning. Mean dose to the spared SMG were reduced by 12% (66.6 Gy vs. 58.9 Gy, p < .001). None of these patients experienced any level 1b LN failures.

CONCLUSION

Selective sparing of the submandibular gland when targeting the level 1b nodes in oral cavity and oropharynx cancer is feasible, reduces the mean dose to submandibular glands and does not result in increased level 1b nodal failure rates. Additional studies with larger cohorts are needed to validate this preliminary observation.

Sparing all salivary glands with IMRT for head and neck cancer: Longitudinal study of patient-reported xerostomia and head-and-neck quality of life

BACKGROUND AND PURPOSE

While parotid-sparing intensity modulated radiotherapy (IMRT) has demonstrated superiority to conventional RT in terms of observer-rated xerostomia, patient-reported outcome measures (PROMs) have only marginally improved. We investigated how sparing all salivary glands affects PROMs.

MATERIALS AND METHODS

Patients treated to the bilateral neck with all-gland-sparing IMRT answered xerostomia (XQ) and head-and-neck quality of life (HNQOL) questionnaires. Longitudinal regression was used to assess the relationship between questionnaire scores and mean bilateral parotid gland (bPG), contralateral submandibular gland (cSMG), and oral cavity (OC) doses. Marginal R² and Akaike information criterion (AIC) were used for model evaluation.

RESULTS

252 patients completed approximately 600 questionnaires. On univariate analysis, bPG, cSMG, and OC doses significantly correlated with XQ-summary, XQ-eating, and HNQOL-eating scores. On multivariate analysis, bPG and OC doses significantly correlated with XQ-summary, XQ-eating, and HNQOL-eating scores; and cSMG dose with HNQOL-summary. Combining doses to all three structures yielded the highest R² for XQ-summary, XQ-rest, XQ-eating, and HNQOL-eating. In the 147 patients who received a mean cSMG dose ≤39Gy, there were no failures in contralateral level IB.

CONCLUSIONS

Reducing doses to all salivary glands maximizes PROMs. A cSMG dose constraint of ≤39Gy does not increase failure risk.