Comparison of Planning Quality and Efficiency Between Conventional and Knowledge-based Algorithms in Nasopharyngeal Cancer Patients Using Intensity Modulated Radiation Therapy.

PURPOSE: Intensity modulated radiation therapy (IMRT) is widely used to achieve a highly conformal dose and improve treatment outcome. However, plan quality and planning time are institute and planner dependent, and no standardized tool exists to recognize an optimal plan. RapidPlan, a knowledge-based algorithm, can generate constraints to assist optimization and produce high-quality IMRT plans. This report evaluated the quality and efficiency of using RapidPlan in nasopharyngeal carcinoma (NPC) IMRT planning. METHODS AND MATERIALS: RapidPlan was configured using 79 radical IMRT plans for NPC; 20 consecutive NPC patients indicated for radical radiation therapy between October 2014 and May 2015 were then recruited to assess its performance. The ability of RapidPlan to produce acceptable plans was evaluated. For plans that could not achieve clinical acceptance, manual touch-up was performed. The IMRT plans produced without RapidPlan (manual plans) and with RapidPlan (RP-2 plans, including those with manual touch-up) were compared in terms of dosimetric quality and planning efficiency. RESULTS: RapidPlan by itself could produce clinically acceptable plans for 9 of the 20 patients; manual touch-up increased the number of acceptable plans (RP-2 plans) to 19. The target dose coverage and conformity were very similar. No difference was found in the maximum dose to the brainstem and optic chiasm. RP-2 plans delivered a higher maximum dose to the spinal cord (46.4 Gy vs 43.9 Gy, P=.002) but a lower dose to the parotid (mean dose to right parotid, 37.3 Gy vs 45.4 Gy; left, 34.4 Gy vs 43.1 Gy; P<.001) and the right cochlea (mean dose, 48.6 Gy vs 52.6 Gy; P=.02). The total planning time for RP-2 plans was significantly less than that for manual plans (64 minutes vs 295 minutes, P<.001). CONCLUSIONS: This study shows that RapidPlan can significantly improve planning efficiency and produce quality IMRT plans for NPC patients.

Should all nasopharyngeal carcinoma with masticator space involvement be staged as T4?

INTRODUCTION: The prognostic significance of the involvement of anatomical masticator space (MS) in nasopharyngeal carcinoma (NPC) was retrospectively reviewed. MATERIAL AND METHODS: 1104 Patients with non-metastatic NPC treated with radical radiotherapy between 1998 and 2010 were re-staged according to the 7th edition of the American Joint Committee on Cancer (AJCC) staging system; tumors with medial pterygoid muscle (MP) and/or lateral pterygoid muscle (LP) involvement but did not fulfill the criteria for T3 or T4 were staged as TX. The tumor volume data, dosimetric data and survival endpoints of different T stage diseases were analyzed and compared to study the significance of MS involvement. RESULTS: The overall MS involvement rate was 61.0%. The median volumes of the primary gross tumor volume were 9.6ml, 15.2ml, 19.9ml, 32.6ml and 77.3ml for T1, T2, TX, T3 and T4, respectively (p<0.001). T1, T2 and TX tumors received higher minimum dose to the gross tumor volume and planning target volume than T3 and T4. Multivariate analysis showed that age, gender, T-/N-classification and the use of chemotherapy were significant prognostic factors for various survival end-points. Patients with TX disease had similar survival rates as with T1-T2; and had a significantly better 5-year overall survival rate (86.6% vs. 76.6%; p=0.013) and a trend of higher 5-year distant failure-free survival rate (91.5% vs. 81.3%; p=0.09) than patients with T3 disease. CONCLUSION: NPC with the involvement of MP and/or LP alone should be classified as T2 disease.

Stereotactic ablative radiotherapy for medically inoperable early stage lung cancer: early outcomes.

OBJECTIVE. To evaluate the clinical outcome and safety of stereotactic ablative radiotherapy for medically inoperable stage I non-small-cell lung carcinoma. DESIGN. Retrospective case series. SETTING. Pamela Youde Nethersole Eastern Hospital, Hong Kong. PATIENTS. All patients with medically inoperable stage I non-small-cell lung carcinoma receiving stereotactic ablative radiotherapy since its establishment in 2008. MAIN OUTCOME MEASURES. Disease control rate, overall survival, and treatment toxicities. RESULTS. Sixteen stage I non-small-cell lung carcinoma patients underwent the procedure from June 2008 to November 2011. The median patient age was 82 years and the majority (81%) had moderate-to-severe co-morbidity based on the Adult Comorbidity Evaluation 27 index. With a median follow-up of 22 months, the 2-year primary tumour control rate, disease-free survival and overall survival rates were 91%, 71% and 87%, respectively. No grade 3 (National Cancer Institute Common Terminology Criteria for Adverse Events) or higher treatment-related complications were reported. CONCLUSION. Stereotactic ablative radiotherapy can achieve a high degree of local control safely in medically inoperable patients with early lung cancer.

The superiority of hybrid-volumetric arc therapy (VMAT) technique over double arcs VMAT and 3D-conformal technique in the treatment of locally advanced non-small cell lung cancer--a planning study.

PURPOSE: To compare the dosimetric performance of three different treatment techniques - conformal radiotherapy (CRT), double arcs volumetric modulated arc therapy (RapidArc, RA) and Hybrid-RapidArc (H-RA) for locally-advanced non-small cell lung cancer (NSCLC). MATERIAL AND METHODS: CRT, RA and H-RA plans were optimized for 24 stage III NSCLC patients. The target prescription dose was 60Gy. CRT consisted of 5-7 coplanar fields, while RA comprised of two 204(o) arcs. H-RA referred to two 204(o) arcs plus 2 static fields, which accounted for approximately half of the total dose. The plans were optimized to fulfill the departmental plan acceptance criteria. RESULTS: RA and H-RA yielded a 20% better conformity compared with CRT. Lung volume receiving >20Gy (V20) and mean lung dose (MLD) were the lowest in H-RA (V20 1.7% and 2.1% lower, MLD 0.59Gy and 0.41Gy lower than CRT & RA respectively) without jeopardizing the low-dose lung volume (V5). H-RA plans gave the lowest mean maximum spinal cord dose (34.4Gy, 3.9Gy

Primary tumor volume of nasopharyngeal carcinoma: prognostic significance for local control.

PURPOSE: To study the prognostic significance of primary tumor volume on local control of nasopharyngeal carcinoma. METHODS AND MATERIALS: Between 1998 and 2001, 308 consecutive patients with nasopharyngeal carcinoma treated with radical intent were staged with MRI. On the basis of the extent of tumor infiltration outlined by a diagnostic radiologist, the gross tumor volume of the primary and involved retropharyngeal nodes (GTV-P) was delineated by a radiation oncologist for three-dimensional conformal radiotherapy to the nasopharyngeal region using the Helax-TMS Planning System. All patients were treated with 2 Gy daily to a total dose of 70 Gy in 6-7 weeks. Additionally, chemotherapy was given to 128 patients (42%). RESULTS: The median GTV-P for the whole series was 22 cm(3) (range, 1.4-218 cm(3)). Although the GTV-P varied substantially within each T stage, the overall correlation between these two parameters was strongly significant (p <0.01), with the median GTV-P 2.7 cm(3) for T1, 13.2 cm(3) for T2, 28.1 cm(3) for T3, and 65.5 cm(3) for T4. With a median follow-up of 1.9 years (range, 0.1-3.9 years), the 3-year local failure-free rate was 87%. The 3-year local failure-free rate was 97% for patients with a GTV-P <15 cm(3) compared with 82% for those with a GTV-P > or =15 cm(3) (p <0.01). On multivariate analysis (with T stage as a covariate), GTV-P remained an independent prognostic factor for the local failure-free rate (hazard ratio, 1.01; 95% confidence interval, 1.00-1.02; p <0.01). CONCLUSION: Our data suggested that GTV-P is a strongly significant factor for predicting local control of nasopharyngeal carcinoma. The risk of local failure was estimated to increase by 1% for every 1 cm(3) increase in primary tumor volume.