Impact of geometric variations on delivered dose in highly focused single vocal cord IMRT.

PURPOSE: To investigate the robustness of single vocal cord intensity modulated radiation therapy (IMRT) treatment plans for set-up errors, respiration, and deformation. MATERIAL AND METHODS: Four-dimensional computed tomography (4D-CT) scans of 10 early glottic carcinoma patients, previously treated with conventional techniques, were used in this simulation study. For each patient a pre-treatment 4D-CT was used for IMRT planning, generating a reference dose distribution. Prescribed PTV dose was 66 Gy. The impact of systematic set-up errors was simulated by applying shifts of ± 2 mm to the planning CT scans, followed by dose re-calculation with original beam segments, MUs, etc. Effects of respiration and deformation were determined utilizing extreme inhale and exhale CT scans, and repeat scans acquired after 22 Gy, 44 Gy, and 66 Gy, respectively. All doses were calculated using Monte Carlo dose simulations. RESULTS: Considering all investigated geometrical perturbations, reductions in the clinical target volume (CTV) V95%, D98%, D2%, and generalized equivalent uniform dose (gEUD) were limited to 1.2 ± 2.2%, 2.4 ± 2.9%, 0.2 ± 1.8%, and 0.6 ± 1.1 Gy, respectively. The near minimum dose, D98%, was always higher than 89%, and gEUD always remained higher than 66 Gy. Planned contra-lateral (CL) vocal cord DMean, gEUD, and V40 Gy were 38.2 ± 6.0 Gy, 43.4 ± 5.6 Gy, and 42.7 ± 14.9%. With perturbations these values changed by -0.1 ± 4.3 Gy, 0.1 ± 4.0 Gy, and -1.0 ± 9.6%, respectively. CONCLUSIONS: On average, CTV dose reductions due to geometrical perturbations were very low, and sparing of the CL vocal cord was maintained. In a few observations (6 of 103 simulated situations), the near-minimum CTV-dose was around 90%, requiring attention in deciding on a future clinical protocol.

Comparison of macroscopic pathology measurements with magnetic resonance imaging and assessment of microscopic pathology extension for colorectal liver metastases.

PURPOSE: To compare pathology macroscopic tumor dimensions with magnetic resonance imaging (MRI) measurements and to establish the microscopic tumor extension of colorectal liver metastases. METHODS AND MATERIALS: In a prospective pilot study we included patients with colorectal liver metastases planned for surgery and eligible for MRI. A liver MRI was performed within 48 hours before surgery. Directly after surgery, an MRI of the specimen was acquired to measure the degree of tumor shrinkage. The specimen was fixed in formalin for 48 hours, and another MRI was performed to assess the specimen/tumor shrinkage. All MRI sequences were imported into our radiotherapy treatment planning system, where the tumor and the specimen were delineated. For the macroscopic pathology analyses, photographs of the sliced specimens were used to delineate and reconstruct the tumor and the specimen volumes. Microscopic pathology analyses were conducted to assess the infiltration depth of tumor cell nests. RESULTS: Between February 2009 and January 2010 we included 13 patients for analysis with 21 colorectal liver metastases. Specimen and tumor shrinkage after resection and fixation was negligible. The best tumor volume correlations between MRI and pathology were found for T1-weighted (w) echo gradient sequence (r(s) = 0.99, slope = 1.06), and the T2-w fast spin echo (FSE) single-shot sequence (r(s) = 0.99, slope = 1.08), followed by the T2-w FSE fat saturation sequence (r(s) = 0.99, slope = 1.23), and the T1-w gadolinium-enhanced sequence (r(s) = 0.98, slope = 1.24). We observed 39 tumor cell nests beyond the tumor border in 12 metastases. Microscopic extension was found between 0.2 and 10 mm from the main tumor, with 90% of the cases within 6 mm. CONCLUSIONS: MRI tumor dimensions showed a good agreement with the macroscopic pathology suggesting that MRI can be used for accurate tumor delineation. However, microscopic extensions found beyond the tumor border indicate that caution is needed in selecting appropriate tumor margins.

IMRT for image-guided single vocal cord irradiation.

PURPOSE: We have been developing an image-guided single vocal cord irradiation technique to treat patients with stage T1a glottic carcinoma. In the present study, we compared the dose coverage to the affected vocal cord and the dose delivered to the organs at risk using conventional, intensity-modulated radiotherapy (IMRT) coplanar, and IMRT non-coplanar techniques. METHODS AND MATERIALS: For 10 patients, conventional treatment plans using two laterally opposed wedged 6-MV photon beams were calculated in XiO (Elekta-CMS treatment planning system). An in-house IMRT/beam angle optimization algorithm was used to obtain the coplanar and non-coplanar optimized beam angles. Using these angles, the IMRT plans were generated in Monaco (IMRT treatment planning system, Elekta-CMS) with the implemented Monte Carlo dose calculation algorithm. The organs at risk included the contralateral vocal cord, arytenoids, swallowing muscles, carotid arteries, and spinal cord. The prescription dose was 66 Gy in 33 fractions. RESULTS: For the conventional plans and coplanar and non-coplanar IMRT plans, the population-averaged mean dose ± standard deviation to the planning target volume was 67 ± 1 Gy. The contralateral vocal cord dose was reduced from 66 ± 1 Gy in the conventional plans to 39 ± 8 Gy and 36 ± 6 Gy in the coplanar and non-coplanar IMRT plans, respectively. IMRT consistently reduced the doses to the other organs at risk. CONCLUSIONS: Single vocal cord irradiation with IMRT resulted in good target coverage and provided significant sparing of the critical structures. This has the potential to improve the quality-of-life outcomes after RT and maintain the same local control rates.

Clinical introduction of Monte Carlo treatment planning: a different prescription dose for non-small cell lung cancer according to tumor location and size.

PURPOSE: To provide a prescription dose for Monte Carlo (MC) treatment planning in patients with non-small-cell lung cancer according to tumor size and location. METHODS: Fifty-three stereotactic radiotherapy plans designed using the equivalent path-length (EPL) algorithm were re-calculated using MC. Plans were compared by the minimum dose to 95% of the PTV (D95), the heterogeneity index (HI) and the mean dose to organs at risk (OARs). Based on changes in D95, the prescription dose was converted from EPL to MC. Based on changes in HI, we examined the feasibility of MC prescription to plans re-calculated but not re-optimized with MC. RESULTS: The MC fraction dose for peripheral tumors is 16-18 Gy depending on tumor size. For central tumors the MC dose was reduced less than for peripheral tumors. The HI decreased on average by 4-9% in peripheral tumors and 3-5% in central tumors. The mean dose to OARs was lower for MC than EPL, and correlated strongly (R(2)=0.98-0.99). CONCLUSION: For the conversion from EPL to MC we recommend a separate prescription dose according to tumor size. MC optimization is not required if a HI > or = 70% is accepted. Dose constraints to OARs can be easily converted due to the high EPL-MC correlation.

Longitudinal changes in quality of life and costs in long-term survivors of tumors of the oropharynx treated with brachytherapy or surgery.

PURPOSE: Based on earlier studies we were interested in finding out if longitudinal assessment of quality of life (QoL) and costs in long-term survivors of oropharyngeal cancers treated with external beam radiation therapy and brachytherapy (BT) or surgery and postoperative radiotherapy showed a change in QoL over the years. Besides, we were curious to know how much the costs per life year and the QALY would be for this patient group. METHODS AND MATERIALS: Performance status scales: eating in public, understandability of speech, normalcy of diet, xerostomia and ability to swallow were determined in 2003 and 2005. In 2005, the responses to EORTC QLQ-C30, EORTC H&N35, and the Euroqol questionnaire were also measured. Costs and quality-adjusted life years (QALYs) were calculated. RESULTS: Eating in public, understandability of speech, and normalcy of diet significantly differed in favor of BT. Surgical patients experienced more speech, teeth, and mouth-opening problems. Mean costs and QALYs for BT were 16,112 euros and 56,060 euros and for surgery 26,590 euros and 93,275 euros, respectively. CONCLUSIONS: QoL scores don't change over time. Due to the number of admission days, surgery is more costly. Difference in costs for QALYs in favor of BT was observed.

Interstitial radiation therapy for early-stage nasal vestibule cancer: a continuing quest for optimal tumor control and cosmesis.

INTRODUCTION: This article reports on the effectiveness, cosmetic outcome, and costs of interstitial high-dose-rate (HDR) brachytherapy for early-stage cancer of the nasal vestibule (NV) proper and/or columella high-dose-rate (HDR). METHODS AND MATERIALS: Tumor control, survival, cosmetic outcome, functional results, and costs were established in 64 T1/T2N0 nasal vestibule cancers treated from 1991-2005 by fractionated interstitial radiation therapy (IRT) only. Total dose is 44 Gy: 2 fractions of 3 Gy per day, 6-hour interval, first and last fraction 4 Gy. Cosmesis is noted in the chart by the medical doctor during follow-up, by the patient (visual analog scale), and by a panel. Finally, full hospital costs are computed. RESULTS: A local relapse-free survival rate of 92% at 5 years was obtained. Four local failures were observed; all four patients were salvaged. The neck was not treated electively; no neck recurrence in follow-up was seen. Excellent cosmetic and functional results were observed. With 10 days admission for full treatment, hospital costs amounted to euro5772 (7044 US dollars). CONCLUSION: Excellent tumor control, cosmesis, and function of nasal airway passage can be achieved when HDR-IRT for T1/T2N0 NV cancers is used. For the more advanced cancers (Wang classification: T3 tumor stage), we elect to treat by local excision followed by a reconstructive procedure. The costs, admission to hospital inclusive, for treatment by HDR-IRT amounts to euro5772 (7044 US dollars). This contrasts substantially with the full hospital costs when NV cancers are treated by plastic reconstructive surgery, being on average threefold as expensive.

Compliance and efficiency before and after implementation of a clinical practice guideline for laryngeal carcinomas.

We evaluated whether the implementation of a nationwide clinical practice guideline for diagnosis, treatment and follow-up of laryngeal carcinomas led to changes in hospital costs, balanced against clinical changes observed following the guideline's implementation. Charts of 822 patients with larynx carcinoma (459 treated before the introduction of the guideline and 363 thereafter) in five hospitals were retrospectively investigated. In all phases, no differences in total hospital costs were observed after the guideline's implementation. Total mean costs were Euro 3,207 (95%CI 3,091-3,395) for diagnosis, Euro 3,169 (2,153-4,182), Euro 5,026 (3,996-6,057), Euro 6,458 (5,579-7,337), Euro 8,037 (7,469-8,606), Euro 12,765 (10,763-14,769), Euro 19,227 (16,848-21,605) for treatment of dysplasia, carcinoma in situ, T1, T2, T3 and T4 carcinoma, respectively, and Euro 1,856 (1,491-2,220) for 1 year disease-free follow-up. In an earlier study, we observed several positive changes after the guideline's implementation. Balanced against the equal costs before and after the guideline's implementation, we conclude that the efficiency of the care process improved.

Chemotherapy and high-dose-rate brachytherapy in the management of advanced cancers of the nasopharynx: clinical impact of high technology--is it worth the cost?

PURPOSE: The aim of this study was to calculate the costs of chemotherapy and high-dose-rate brachytherapy in advanced-stage nasopharyngeal cancer. It is argued whether the effect of chemotherapy and this type of high-dose, high-precision radiation therapy is worth the costs. METHODS AND MATERIALS: Clinical results of Stage III-IVB nasopharyngeal cancer in patients treated between 1991 and 2000 are reported. Treatment was broken down into five categories: workup, chemotherapy, preparation of radiation therapy, and application of radiation. For each category, costs were computed. Nasopharyngeal cancer treatment costs were compared with costs previously reported on patients treated for cancers of the oral cavity, larynx, and oropharynx. RESULTS: With the addition of neoadjuvant chemotherapy and high cumulative doses of radiation (77-81 Gy) with brachytherapy, disease-free survival increased from 48% to 74% (p=0.002), and overall survival increased from 35% to 72% (p=0.005). The Rotterdam protocol has been implemented stepwise: as of 1991, costs per patient increased from 4521 Euros (US$5023; 2001 exchange rate [December]: 1 Euro approximately 0.88 US$) for conventional external beam radiation therapy to 13,728 Euros (US$15,253) in 2000 for combinations of chemotherapy, conventional external beam radiation therapy, and brachytherapy. In case of stereotactic radiotherapy, the cost was 14,516 Euros (US$16,495). CONCLUSIONS: Costs for cancer in the nasopharynx vary from 14,528 Euros (US$16,509) to 15,316 Euros (US$17,405) in case of brachytherapy and stereotactic radiotherapy, respectively, if follow-up costs are added. The treatment cost for other head and neck sites was 21,858 Euros (US$24,126). Given the improvement in survival, the sparing capabilities of current high-dose, high-precision radiotherapy techniques, and the favorable cost profile compared with other sites, it is argued that costs should not be considered prohibitive for the introduction of chemotherapy and high-technology-based radiotherapy in advanced nasopharyngeal cancer.