Factors influencing the parotid function in nasopharyngeal carcinoma treated with parotid-sparing radiotherapy

A prediction model for xerostomia in locoregionally advanced nasopharyngeal carcinoma patients receiving radical radiotherapy

Background

This study was to evaluate the predictors of xerostomia and Grade 3 xerostomia in locoregionally advanced nasopharyngeal carcinoma (NPC) patients receiving radical radiotherapy and establish prediction models for xerostomia and Grade 3 xerostomia based on the predictors.

Methods

Totally, 365 patients with locoregionally advanced NPC who underwent radical radiotherapy were randomly divided into the training set (n = 255) and the testing set (n = 110) at a ratio of 7:3. All variables were included in the least absolute shrinkage and selection operator regression to screen out the potential predictors for xerostomia as well as the Grade 3 xerostomia in locoregionally advanced NPC patients receiving radical radiotherapy. The random forest (RF), a decision tree classifier (DTC), and extreme-gradient boosting (XGB) models were constructed. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), area under the curve (AUC) and accuracy were analyzed to evaluate the predictive performance of the models.

Results

In the RF model for predicting xerostomia, the sensitivity was 1.000 (95%CI 1.000–1.000), the PPV was 0.990 (95%CI 0.975–1.000), the NPV was 1.000 (95%CI 1.000–1.000), the AUC was 0.999 (95%CI 0.997–1.000) and the accuracy was 0.992 (95%CI 0.981–1.000) in the training set. The sensitivity was 0.933 (95%CI 0.880–0.985), the PPV was 0.933 (95%CI 0.880–0.985), and the AUC was 0.915 (95%CI 0.860–0.970) in the testing set. Hypertension, age, total radiotherapy dose, dose at 50% of the left parotid volume, mean dose to right parotid gland, mean dose to oral cavity, and course of induction chemotherapy were important variables associated with the risk of xerostomia in locoregionally advanced NPC patients receiving radical radiotherapy. The AUC of DTC model for predicting xerostomia was 0.769 (95%CI 0.666–0.872) in the testing set. The AUC of the XGB model for predicting xerostomia was 0.834 (0.753–0.916) in the testing set. The RF model showed the good predictive ability with the AUC of 0.986 (95%CI 0.972–1.000) in the training set, and 0.766 (95%CI 0.626–0.905) in the testing set for identifying patients who at high risk of Grade 3 xerostomia in those with high risk of xerostomia.

Conclusions

An RF model for predicting xerostomia in locoregionally advanced NPC patients receiving radical radiotherapy and an RF model for predicting Grade 3 xerostomia in those with high risk of xerostomia showed good predictive ability.

Prognostic nomogram of xerostomia for patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy

Xerostomia is a common radiation-induced late complication after radiotherapy. Identifying predictive factors for xerostomia will lead to better treatments and improve the quality of life. This study was conducted to establish an effective predictive nomogram for xerostomia by assessing stage I-IVb (AJCC 7th edition) NPC patients between September 2015 and March 2016. Xerostomia was evaluated via the RTOG/EORTC system. The primary endpoint was grade 2-3 xerostomia 1 year after treatment. The predictive factors for xerostomia were analysed using logistic regression analysis. A nomogram was constructed based on combining the predictors and clinical variables. In total, 102 patients with grade 0-1 xerostomia and 93 patients with grade 2-3 xerostomia were included. The independent predictive factors for xerostomia were V25, V30, V35, and V45 of the ipsilateral parotid gland and mean dose of the contralateral parotid gland. The calibration plot for the probability of xerostomia showed good agreement between prediction by the nomogram and actual observation. The concordance index of the nomogram for predicting xerostomia was 0.796 (95% CI: 0.735-0.857, P <0.001), which was higher than any single dosimetric parameter. Our results indicated that the nomogram provided a more accurate prediction of grade 2-3 xerostomia 1 year after treatment.

Predictors for improvement of xerostomia in nasopharyngeal carcinoma patients receiving intensity-modulated radiotherapy

To identify predictors for improvement of xerostomia in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT).Patients diagnosed with stage I-IVb NPC (according to the 7th edition of the American Joint Committee on Cancer) between September 2015 and March 2016 were retrospectively analyzed. All the patients received IMRT. Predictors for improvement of xerostomia were analyzed using logistic regression analysis. Receiver operating characteristic curve analysis was used to identify the most appropriate cut-off values for predicting factors.This study included 195 patients: xerostomia improved in 109 patients and xerostomia remained unchanged in 86 patients. Volume of the parotid gland ≤52.2 cm was a risk factor for xerostomia improvement (odds ratio [OR] = 3.506, 95% confidence interval [CI]: 1.932-6.362, P = .001). The mean dose of <39 Gy to the ipsilateral parotid gland was a protective factor (OR = 0.417, 95% CI: 0.271-0.641, P = .001). V30 of the contralateral parotid gland ≤52% was a protective factor (OR = 0.593, 95% CI: 0.462-0.760, P = .001).Volume of the parotid gland, the mean dose of the ipsilateral parotid gland, and V30 of the contralateral parotid gland were independent predictors for improvement of xerostomia.

A systematic review of salivary gland hypofunction and xerostomia induced by cancer therapies: management strategies and economic impact

PURPOSE

This systematic review aimed to assess the literature for management strategies and economic impact of salivary gland hypofunction and xerostomia induced by cancer therapies and to determine the quality of evidence-based management recommendations.

METHODS

The electronic databases of MEDLINE/PubMed and EMBASE were searched for articles published in English since the 1989 NIH Development Consensus Conference on the Oral Complications of Cancer Therapies until 2008 inclusive. For each article, two independent reviewers extracted information regarding study design, study population, interventions, outcome measures, results, and conclusions.

RESULTS

Seventy-two interventional studies met the inclusion criteria. In addition, 49 intensity-modulated radiation therapy (IMRT) studies were included as a management strategy aiming for less salivary gland damage. Management guideline recommendations were drawn up for IMRT, amifostine, muscarinic agonist stimulation, oral mucosal lubricants, acupuncture, and submandibular gland transfer.

CONCLUSIONS

There is evidence that salivary gland hypofunction and xerostomia induced by cancer therapies can be prevented or symptoms be minimized to some degree, depending on the type of cancer treatment. Management guideline recommendations are provided for IMRT, amifostine, muscarinic agonist stimulation, oral mucosal lubricants, acupuncture, and submandibular gland transfer. Fields of sparse literature identified included effects of gustatory and masticatory stimulation, specific oral mucosal lubricant formulas, submandibular gland transfer, acupuncture, hyperbaric oxygen treatment, management strategies in pediatric cancer populations, and the economic consequences of salivary gland hypofunction and xerostomia.

A systematic review of salivary gland hypofunction and xerostomia induced by cancer therapies: prevalence, severity and impact on quality of life

PURPOSE

This systematic review aimed to assess the literature for prevalence, severity, and impact on quality of life of salivary gland hypofunction and xerostomia induced by cancer therapies.

METHODS

The electronic databases of MEDLINE/PubMed and EMBASE were searched for articles published in English since the 1989 NIH Development Consensus Conference on the Oral Complications of Cancer Therapies until 2008 inclusive. Two independent reviewers extracted information regarding study design, study population, interventions, outcome measures, results and conclusions for each article.

RESULTS

The inclusion criteria were met by 184 articles covering salivary gland hypofunction and xerostomia induced by conventional, 3D conformal radiotherapy or intensity-modulated radiotherapy in head and neck cancer patients, cancer chemotherapy, total body irradiation/hematopoietic stem cell transplantation, radioactive iodine treatment, and immunotherapy.

CONCLUSIONS

Salivary gland hypofunction and xerostomia are induced by radiotherapy in the head and neck region depending on the cumulative radiation dose to the gland tissue. Treatment focus should be on optimized/new approaches to further reduce the dose to the parotids, and particularly submandibular and minor salivary glands, as these glands are major contributors to moistening of oral tissues. Other cancer treatments also induce salivary gland hypofunction, although to a lesser severity, and in the case of chemotherapy and immunotherapy, the adverse effect is temporary. Fields of sparse literature included pediatric cancer populations, cancer chemotherapy, radioactive iodine treatment, total body irradiation/hematopoietic stem cell transplantation, and immunotherapy.

The current status of intensity-modulated radiation therapy in the treatment of nasopharyngeal carcinoma

Radiation therapy is the mainstay of treatment in nasopharyngeal carcinoma, alone or in combination with chemotherapy. In the early stage, it can be managed by radiotherapy alone. For locally advanced-stage disease, several meta-analyses have demonstrated the role of concurrent chemoradiotherapy. Conventional radiation therapy results in significant side effects, particular xerostomia, leading to poor quality of life. With the maturity of intensity-modulated radiation therapy in the recent 10 years, more and more evidences have shown the advantages of intensity-modulated radiation therapy over conventional radiation therapy, regarding the local-regional control, survival rate and quality of life. This article reviews the utilization of intensity-modulated radiation therapy in the management of nasopharyngeal carcinoma with respect to its technical advantages, clinical outcome, critical organ sparing and quality of life, and the dilemma in target delineation. In particular, an issue of treatment-related dysphagia will also be discussed.