Parotid-gland-sparing 3D conformal radiotherapy in patients with bilateral radiotherapy of the head and neck region--results in clinical practice

Factors Influencing the Survival Rate of Teeth and Implants in Patients after Tumor Therapy to the Head and Neck Region-Part 1: Tooth Survival

We aimed to evaluate possible factors influencing the long-term survival of teeth after tumor therapy (TT) to the head and neck region with and without radiation. Between January 2019 and January 2020, patients who underwent TT for head and neck cancer and received dental treatment before and after TT at the Department of Prosthetic Dentistry of the Martin Luther University Halle-Wittenberg were enrolled in the study. Clinical examination with assessment of dental status and stimulated salivary flow rate (SFR) was performed and information about disease progression and therapy was retrieved from medical records. Of 118 patients (male: 70.3%; mean age: 63.2 ± 12.4 years), 95 received radiotherapy (RT), and 47 were administered radio-chemotherapy (RCT). The teeth of irradiated patients exhibited a lower 5-year survival probability (74.2%) than those of non-irradiated patients (89.4%). The risk of loss (RL) after RT increased with nicotine use, presence of intraoral defects, reduced SFR, RCT and regarding mandibular teeth, and decreased with crowning following TT. Lower SFR increased the RL even without RT. Consideration of patient’s treatment history, individual risk profile, and clinical findings during the prosthetic planning phase could enable earlier, more targeted dental treatment after TT (e.g., timely crowning).

Salivary miR-93 and miR-200a as post-radiotherapy biomarkers in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma is the 6th most malignant tumor entity worldwide and has exhibited a 5-year mortality of approximately 50% for the last fifty years. For the therapy monitoring and successful management of this tumor entity new and easily accessible biomarkers are greatly needed. The aim of the study was to determine whether and to what extent microRNAs, a class of small regulatory RNAs, are detectable in saliva post-radiation therapy. The expression and feasibility as therapy monitoring marker of the microRNAs were analyzed by RT-qPCR in 83 saliva samples from 33 patients collected at several time points pre-, during and post-radiotherapy treatment. Ten head and neck squamous cell carcinoma- or radiation-associated microRNAs (miR-93, miR-125a, miR-142-3p, miR-200a, miR-203, miR-213, let-7a, let-7b, let-7g and let-7i) were analyzed. All were detectable to a different extent in the saliva of the patients. miR-93 and miR-200a were significantly higher expressed 12 months post-radiotherapy than at baseline (p=0.047 and p=0.036). These results point towards miR-93 and miR-200a as biomarkers for the treatment monitoring post-radiation of head and neck squamous cell carcinoma.

Management algorithm for HIV-associated parotid lymphoepithelial cysts

We report an evidence-based management algorithm for benign lymphoepithelial cysts (BLEC) of the parotid glands in HIV patients based on long-term outcomes after radiation therapy. From 1987 to 2013, 72 HIV-positive patients with BLEC of the parotid glands treated at our institutions were identified and their medical records were reviewed and analyzed. The primary endpoint of our study was to determine a dose response in HIV patients with BLEC. In group A (≤18 Gy), which received a median dose of 10 Gy (8-18), overall response (OvR), complete response (CR), partial response (PR), and local failure (LF) was experienced by 7, 7, 0, and 93 %, respectively. In group B (≥22.5 Gy), which received a median dose of 24 Gy (22.5-30), OvR, CR, PR, and LF was experienced by 88, 65, 23, and 12 %. Logistic regression revealed that higher dose (≥22.5 Gy) predicted for cosmetic control (p = 0.0003). Multiple regression analysis revealed higher dose predicted for cosmetic control (p = 0.0001) after adjusting for confounding variables (age, gender, race, HAART use, BLEC duration, and fractionation size). No patients in either group experienced RTOG grade ≥3 toxicities. A radiation dose of 24 Gy delivered in 12-16 fractions of 1.5-2 Gy per fraction provides long-term cosmetic control in HIV-positive patients with BLEC of the parotid glands.

Radiation caries in nasopharyngeal carcinoma patients after intensity-modulated radiation therapy: A cross-sectional study

Background/purpose

The exact dose of intensity-modulated radiation therapy (IMRT) associated with tooth damage is mostly unknown. We aim to evaluate the severity of dental lesions after IMRT and the correlation with the radiation dose to the dentition in patients with nasopharyngeal carcinoma (NPC).

Materials and methods

This was a cross-sectional study of 42 patients with NPC who completed IMRT in 2011. Each premolar tooth was divided into 13 sites. Teeth were evaluated using a validated index and subsequently categorized at each divided site. The relationship between dose distribution and the caries severity score was analyzed using logistic models. The odds of developing caries damage were evaluated using odds ratios.

Results

A total of 4342 sites from 334 premolar teeth were evaluated. For sites exposed to 30–60 Gy, the odds of developing caries damage were 12–200 times greater compared with sites unexposed to IMRT. A new radiation caries lesion was likely to occur when the dose was >35.8 Gy after 17 days' radiation therapy (P < 0.05).

Conclusion

The findings suggest that new tooth damage was likely to occur at doses > 35.8 Gy, and care should be taken throughout the treatment planning process to limit tooth doses to < 50 Gy in NPC patients.

Simultaneous integrated boost-intensity-modulated radiotherapy in head and neck cancer

OBJECTIVES/HYPOTHESIS

To review toxicity and outcomes in patients with head and neck cancer treated with simultaneous integrated boost-intensity-modulated radiotherapy (SIB-IMRT).

STUDY DESIGN

Review of experience with the SIB-IMRT technique.

METHODS

Fifty patients were treated with the SIB-IMRT technique. Two possible schedules of radiation therapy (RT) were used: SIB 70 (70/60/54 in 33 fractions) and SIB 66 (66/60/54 in 33 fractions). Forty-one patients also received chemotherapy.

RESULTS

All but two patients completed treatment as prescribed. No G4 acute toxicity has been reported in our series. We did not observe any G3 to G4 chronic toxicity, apart from one case of cutaneous necrosis. After a median follow-up of 23.3 months (range, 1-60 months), 41 patients (82%) were alive and negative for disease, and one patient (2%) was alive with distant metastases. Eight patients (16%) died, seven because of progressive disease and one for other causes.

CONCLUSIONS

SIB-IMRT is a highly effective and safe technique of RT in the treatment of head and neck cancer.

The influence of parotid gland sparing on radiation damages of dental hard tissues

OBJECTIVE

The aim of the present study was to evaluate whether radiation damage on dental hard tissue depends on the mean irradiation dose the spared parotid gland is subjected to or on stimulated whole salivary flow rate.

MATERIAL AND METHODS

Between June 2002 and October 2008, 70 patients with neck and cancer curatively irradiated were included in this study. All patients underwent dental treatment referring to the guidelines and recommendations of the German Society of Dental, Oral and Craniomandibular Sciences prior, during, and after radiotherapy (RT). During the follow-up period of 24 months, damages on dental hard tissues were classified according to the RTOG/EORTC guidelines. The mean doses (D(mean)) during spared parotid gland RT were determined. Stimulated whole saliva secretion flow rates (SFR) were measured before RT and 1, 6, 12, 24 months after RT.

RESULTS

Thirty patients showed no carious lesions (group A), 18 patients developed sporadic carious lesions (group B), and 22 patients developed general carious lesions (group C). Group A patients received a D mean of 21.2 ± 11.04 Gy. Group B patients received a D(mean) of 26.5 ± 11.59 Gy and group C patients received a D(mean) of 33.9 ± 9.93 Gy, respectively. The D(mean) of group A was significantly lower than the D(mean) of group C (p < 0.001). Additionally, the mean SFR 6 months after RT of group A was significantly higher than the mean SFR of group C (p < 0.01).

CONCLUSIONS

Irradiation damage on dental hard tissue correlates with increased mean irradiation doses as well as decreased salivary flow rates.

CLINICAL RELEVANCE

Parotid gland sparing resulting in a dose below 20 Gy reduces radiation damage on dental hard tissues, and therefore, the dose may act as a predictor for the damage to be expected.

Parotid gland-recovery after radiotherapy in the head and neck region--36 months follow-up of a prospective clinical study

Background

The aim of the present study was to evaluate the recovery potential of the parotid glands after using either 3D-conformal-radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) by sparing one single parotid gland.

Methods

Between 06/2002 and 10/2008, 117 patients with head and neck cancer were included in this prospective, non-randomised clinical study. All patients were treated with curative intent. Salivary gland function was assessed by measuring stimulated salivary flow at the beginning, during and at the end of radiotherapy as well as 1, 6, 12, 24, and 36 months after treatment. Measurements were converted to flow rates and normalized relative to rates before treatment. Mean doses (D_mean) were calculated from dose-volume histograms based on computed tomographies of the parotid glands.

Results

Patients were grouped according to the D_mean of the spared parotid gland having the lowest radiation exposure: Group I - D_mean < 26 Gy (n = 36), group II - D_mean 26-40 Gy (n = 45), and group III - D_mean > 40 Gy (n = 36). 15/117 (13%) patients received IMRT. By using IMRT as compared to 3D-CRT the D_mean of the spared parotid gland could be significantly reduced (D_mean IMRT vs. 3D-CRT: 21.7 vs. 34.4 Gy, p < 0.001). The relative salivary flow rates (RFSR) as a function of the mean parotid dose after 24 and 36 months was in group I 66% and 74%, in group II 56% and 49%, and in group III 31% and 24%, respectively. Multiple linear regression analyses revealed that the parotid gland dose and the tumor site were the independent determinants 12 and 36 months after the end of RT. Patients of group I and II parotid gland function did recover at 12, 24, and 36 months after the end of RT.

Conclusions

If a D_mean < 26 Gy for at least one parotid gland can be achieved then this is sufficient to reach complete recovery of pre-RT salivary flow rates. The radiation volume which depends on tumor site did significantly impact on the D_mean of the parotids, and thus on the saliva flow and recovery of parotid gland.

Impact of Radiotherapy Dose on Dentition Breakdown in Head and Neck Cancer Patients

PURPOSE: To evaluate the severity of post-radiation dental lesions and possible correlation with radiation dose to the teeth in patients treated for head and neck cancers. METHODS AND MATERIALS: Data from 93 head and neck radiotherapy patients treated between 1997 and 2008 were analyzed retrospectively. The main effect, radiation dose to the individual teeth, was evaluated with covariates of elapsed time after radiation, xerostomia, topical fluoride use, and oral hygiene status included. Patients' radiotherapy plans were used to calculate cumulative exposure for each tooth. Patients' teeth were evaluated using a validated index and then categorized as having none/slight or moderate/severe post-radiation damage. RESULTS: Patients (31 females, 62 males) ranged in age from 18-82 yrs (mean=57). The number of teeth/patient ranged from 3-30 (mean=20) with a total of 1873 teeth evaluated. Overall, 51% of teeth had moderate/severe damage, with the remaining having little or none. Using odds ratios and 95% confidence intervals, the odds for moderate/severe damage were 2-3x greater for teeth exposed to between 30-60 Gy as compared to no radiation. However, for teeth exposed to ≥60 Gy as compared to no radiation the odds of moderate/severe tooth damage was greater by a magnitude of 10 times. CONCLUSIONS: The results indicate that there is minimal tooth damage below 30 Gy (salivary gland threshold), a greater than 1:1 increased dose-response between 30-60y likely related to salivary gland damage, and a critical threshold of ≥60Gy which may be linked to direct effects of radiation on tooth structure. These findings suggest that care should be taken during the treatment planning process to limit tooth dose, and when clinically possible to limit tooth dose to less than 60 Gy.

Investigations on parotid gland recovery after IMRT in head and neck tumor patients

PURPOSE

in recent years, the role of intensity-modulated radiotherapy (IMRT) for head and neck irradiation has increased. The main motivation is sparing the parotid gland and reduction of xerostomia. Generally, relative parotid volumes have been evaluated for treatment outcome and planning constraints, neglecting that absolute parotid volumes can vary significantly. The aim of the present study was to investigate changes in parotid gland function and set this in relation to absolute volumes.

MATERIAL AND METHODS

46 head and neck patients were treated by sparing at least the contralateral parotid gland. The mean dose to the contralateral gland was limited to 26 Gy. Parotid function was measured with scintigraphy before and at 3, 6, 9, and 12 months after radiotherapy. Gland recovery was correlated with absolute parotid gland volumes and mean dose. Finally the dose-effect relationship was investigated.

RESULTS

the dose-volume histograms (DVHs) for the ipsi- and contralateral glands were significantly different. A correlation between absolute volumes receiving certain doses and the function loss after 3, 6, 9, and 12 months was found. The most significant correlation was found for the absolute volume that received at least 40 Gy (aV40). ED50 values of 23-38 Gy were observed for more than 50% function loss and and 52-68 Gy afor more than 75% function loss.

CONCLUSION

the mean dose, aV40 or aV26, revealed similar correlations with the excretion rate and with recovery. Hence, also absolute volumes can be used for treatment planning. Longer recovery times show higher ED50 values indicating partial regeneration of gland functions.

Effect of gamma irradiation on ultimate tensile strength of enamel and dentin

The effect of gamma irradiation therapy on the ultimate tensile strength (UTS) of enamel and dentin in relation to prism orientation, dentin tubule orientation, and location is unknown. It was hypothesized that tubule and prism orientation, location, and irradiation have an effect on the UTS of dental structures. Forty human third molars were used, half of which were subjected to 60 Gy of gamma irradiation, in daily increments of 2 Gy. The specimens were evaluated by microtensile testing. Results showed that irradiation treatment significantly decreased the UTS of coronal and radicular dentin and of enamel, regardless of tubule or prism orientation. With or without irradiation, enamel was significantly stronger when tested parallel to its prismatic orientation. Coronal and radicular dentin of non-irradiated specimens presented significantly higher UTS when tested perpendicularly to tubule orientation. However, when the teeth were irradiated, the influence of tubule orientation disappeared, demonstrating that irradiation is more harmful to organic components.

The influence of different irradiation doses and desensitizer application on demineralization of human dentin

The aim of the present study was to evaluate the effect of different irradiation doses after desensitizer application on the onset of initial demineralization of human dentin in situ. The root surfaces of 45 freshly extracted caries-free human molars were cleaned, thereby removing the cementum. From each tooth two root dentin specimens were prepared. The specimens were distributed among the following experimental groups: 0, 0.5, 1, 2 and 5Gy. The irradiation dose was fractionally applied (0.5Gy/day). One dentin specimen of each group was inserted into both buccal aspects of nine intraoral mandibular appliances. On one side the specimens were additionally coated with the desensitizer Hyposen (H). On the other side, the specimens were left untreated (C). The appliances were worn by nine persons for five weeks day and night. During meals, the appliance was stored in 10% sucrose solution. After the in situ period, slabs (150microm) were ground and studied using a polarized light microscope. Concerning radiation dose, significant differences were observed between the control and 5Gy group (p<0.05, Tukey s test). Pairwise comparison showed that lesion depths in groups treated with Hyposen were significantly decreased. Within the limitations of this study it can be concluded that higher radiation doses seem to increase the caries susceptibility of dentin. The additional application of a desensitizer hampers the demineralization and might have a caries-protective effect on exposed irradiated root surfaces.